Ground Network Tracking and Acquisition Data Handbook

Preface

This document is under the configuration management of the Goddard Space Flight Center (GSFC) Ground Network (Code 453) Configuration Control Board (CCB).

Proposed changes to this document shall be submitted to the Code 453 CCB along with supportive material justifying the proposed change.

This document may be changed by Documentation Change Notice (DCN) or by complete revision.

Questions concerning this document and proposed changes shall be addressed to:

Project Manager Code 453 Goddard Space Flight Center Greenbelt, Maryland 20771

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Change Information Page

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DCN Control Sheet

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Contents

Preface

Section 1. Introduction

1.1 Purpose and Scope ............................................................................................................ 1-1

1.2 Management Responsibility .............................................................................................. 1-1

1.3 References ......................................................................................................................... 1-1

1.4 Corrections and Improvements ......................................................................................... 1-1

Section 2. Network Tracking Systems

2.1 Ground Network Overview ............................................................................................... 2-1

2.2 GN Antenna Systems ......................................................................................................... 2-1

2.2.1 General ..................................................................................................................2-1

2.2.2 System Equipment Capabilities ............................................................................. 2-1

2.2.3 System Configuration............................................................................................. 2-3

2.3 C-band Systems..................................................................................................................2-3

2.3.1 General ..................................................................................................................2-3

2.3.2 System Equipment Capabilities ............................................................................ 2-3

2.3.3 Radar Characteristics.............................................................................................. 2-5

2.3.4 Other Radar Systems..............................................................................................2-6

2.4 Ranging Equipment............................................................................................................2-7

2.4.1 General ..................................................................................................................2-7

2.4.2 SRE........................................................................................................................ 2-7

2.4.3 RER ....................................................................................................................... 2-7

Section 3. Spacecraft Acquisition Data

3.1 General .............................................................................................................................. 3-1

3.2 Acquisition Data Formats .................................................................................................. 3-2

3.2.1 General Overview ................................................................................................. 3-2

3.2.2 Acquisition Data Transmission ........................................................................... 3-28

3.2.3 Acquisition Data Processing .............................................................................. 3-33

3.2.4 LTAS .................................................................................................................. 3-34

3.3 Slaving Systems .............................................................................................................. 3-39

3.3.1 Intrasite Slaving System ...................................................................................... 3-39

Section 4. Tracking Data Formats and Reduction Algorithms

4.1 General .............................................................................................................................. 4-1

4.2 Low-speed Tracking Data Formats ................................................................................... 4-1

4.2.1 General ..................................................................................................................4-1

4.2.2 Universal Tracking Data Format ........................................................................... 4-1

4.2.3 USSTRATCOM B3 Type 2 Radar Data Format ................................................... 4-7

4.2.4 46-character Radar Data Format ........................................................................... 4-9

4.3 High-speed Tracking Data Formats ................................................................................ 4-12

4.3.1 General ................................................................................................................ 4-12

4.3.2 Minimum Delay Data Format ............................................................................. 4-12

4.3.3 High-speed Universal Tracking Data Format ..................................................... 4-17

Section 5. Computer Program Applications

5.1 General .............................................................................................................................. 5-1

5.2 Tracking and Acquisition Programs .................................................................................. 5-1

5.2.1 S-band Tracking Processor System ....................................................................... 5-1

5.2.2 Metric Pointing Assembly ..................................................................................... 5-3

5.2.3 Tracking, Telemetry, and Command Processor .................................................... 5-3

5.3 Data Correction System Applicability .............................................................................. 5-4

5.3.1 TPS S-band (Angle Data Correction) .................................................................... 5-4

5.3.2 RTPS Computer System ........................................................................................ 5-5 a0389toc.doc x 453-HDBK-GN

5.4 Masking ............................................................................................................................. 5-7

5.5 System Applicability ......................................................................................................... 5-7

Section 6. Magnetic Tape Formats and Usage

6.1 Introduction ....................................................................................................................... 6-1

6.2 Tape Block Formats and Tape Operation ......................................................................... 6-1

6.3 Tape Block Types .............................................................................................................. 6-1

6.3.1 Tape Block Type 1: Dynamic System Status Tape (RTPS or STPS) .................. 6-1

6.3.2 Tape Block Type 2 (RTPS or STPS) .................................................................... 6-2

6.3.3 Tape Block Type 3 (RTPS or STPS) .................................................................... 6-2

6.3.4 Tape Block Type 4 (RTPS) ................................................................................... 6-2

6.3.5 Tape Block Type 5 (STPS) ................................................................................... 6-2

Figures

2-1 Typical 9-meter RER Station Configuration...................................................................... 2-4 2-2 SRE Configuration, S-band................................................................................................2-8 2-3 RER Configuration............................................................................................................. 2-9 3-1. IRV Message Body, Five-level (Baudot) Format ............................................................... 3-3 3-2. IRV Message Body, Eight-level (ASCII) Format ............................................................... 3-3 3-3. IIRV Message Body Format ............................................................................................... 3-5 3-4. EPV TTY Message Body Format ....................................................................................... 3-9 3-5. 4800-bit Block EPV Format ............................................................................................. 3-10 3-6. Five-level Coded INP Format with Angles Only ............................................................. 3-19 3-7. Eight-level Coded (ASCII) INP Format with Angles Only ............................................. 3-20 3-8. Five-level Coded INP Format with Range ....................................................................... 3-24 3-9. Eight-level Coded INP Format with Range ...................................................................... 3-25 3-10. Five-level INP Format with Doppler Frequency Field ................................................... 3-25 3-11. USSTRATCOM Two-line Orbital Element Format ...................................................... 3-26 3-12. Illustration of IIRV Data Words Packed into the Data Field of 4800 Block Format....... 3-29 3-13. Illustration of IIRV ASCII Characters Packed into the 4800 Block................................3-30 3-14. Illustration of EPV Data Words Packed into the Data Field of 4800 Block Format ....... 3-31 3-15. Illustration of EPV ASCII Characters Packed into the 4800 Block................................. 3-32 a0389toc.doc xi 453-HDBK-GN

3-16. Launch Trajectory Acquisition System 2400-b/sec Data Format .................................... 3-38 3-17. Intrasite Slaving System................................................................................................... 3-41 4-1. USSTRATCOM B3 Type 2 Radar Data Format ............................................................... 4-7 4-2. C-band 46-character Radar Data Format ............................................................................ 4-9 4-3 Packing of 46-character C-band LSR Data ....................................................................... 4-11 4-4. MDDF Format .................................................................................................................. 4-13 4-5 4800-bit Data Block Structure ........................................................................................... 4-18 4-6. Packing of LSR Data Sample (Universal Format) ........................................................... 4-22 4-7. Packing of HSR Data Field (Universal Format) ............................................................... 4-23 5-1. Typical USB TPS Configuration......................................................................................... 5-2

Tables

2-1. C-band Radar Slew Capabilities ......................................................................................... 2-6 3-1. Station Acquisition Data Format Processing Capabilities ................................................. 3-1 3-2. TTY Symbol Definitions .................................................................................................... 3-2 3-3. IRV Message Body Explanation ....................................................................................... 3-4 3-4. IIRV ASCII TTY Message Body Explanation ................................................................... 3-6 3-5. EPV Message Body Explanation ..................................................................................... 3-11 3-6. EPV Acknowledgment Message ...................................................................................... 3-18 3-7. Explanation of INP Format ............................................................................................... 3-21 3-8. Explanation of USSTRATCOM Two-line Orbital Element Format ................................ 3-27 3-9. Explanation of Launch Trajectory Acquisition System 2400-b/sec Format ................... 3-35 3-10. ISS Slaving Capabilities ................................................................................................. 3-40 4-1. Universal Tracking Data Format ........................................................................................ 4-2 4-2. System-unique Modes ........................................................................................................ 4-5 4-3. Explanation of USSTRATCOM B3 Type-2 Radar Data Format ....................................... 4-8 4-4. Explanation of Radar 46-character Format ...................................................................... 4-10

4-5. Explanation of MDDF Format ......................................................................................... 4-14 4-6. 4800-bit Block Structure, Tracking Data ......................................................................... 4-19 4-7. Source Circuit ID Codes (Octal) ...................................................................................... 4-24 6-1. Speed and Density Combinations........................................................................................ 6-1

Appendix A. Determination of the Local Topocentric Vector at a Tracking Station Appendix B. Antenna Angular Relations Appendix C. Station/Tracker IDs Appendix D. Vehicle Identification Assignment Conventions Appendix E. Tracking Data Format Capabilities Appendix F. Status Block Types Abbreviations and Acronyms

Section 1. Introduction

1.4 Corrections and Improvements

1.4.1

Revisions to this document are prepared and published on an as-required basis. Interim changes, additions, and/or deletions are made by Documentation Change Notice (DCN).

1.4.2

Corrections and/or improvement recommendations are solicited and should be submitted to the Code 453 Ground Network Project Manager.

Section 2. GN Tracking Systems

2.1 Ground Network Overview

The Ground Network consists of NASA-owned and commercial facilities.

a.	Alaska Ground Station (AGS), Alaska, USA
b.	Alaska Satellite Facility (ASF), Alaska, USA
c.	DataLynx, various sites
d.	Hartebeesthoek (HBK), South Africa
e.	Merritt Island (MIL)/Ponce de Leon (PDL) Florida, USA
f.	McMurdo Ground Station (MGS), Antarctica
g.	Santiago (AGO), Chile
h.	Svalbard Ground Station (SGS) Norway
i.	Wallops Ground Station (WGS), Virginia, USA
j.	Universal Space Network (USN), various sites

2.2 GN Antenna Systems

2.2.1 General

The support functions that can be performed with the GN antenna systems include tracking, telemetry, command, air-ground voice, and television capabilities. Technical capabilities of the GN antennas are described in Ground Network User’s Guide, 453-GNUG. Detailed antenna characteristics are also available on-line from the Mission Station Information System (MSIS). (http://msis.gsfc.nasa.gov/)

2.2.2 System Equipment and Capabilities

2.2.2.1 Angle Tracking (9-m antenna)

The S-band systems employ monopulse autotrack principles to generate error signals for application to the antenna servo/computer system and thereby maintain the antenna pointed toward the spacecraft transmitted signal. To aid in initial acquisition, a program (computer-controlled) mode is also available. The program mode uses orbital prediction data to generate angle data for the antenna. Antenna angle readings are compared with predicted angles, and corresponding error signals are generated. In addition, the 9-m initial acquisition of the spacecraft Radio Frequency (RF) signal may be facilitated by means of a small, wider beamwidth acquisition parabolic antenna, mounted at the edge of the 9-m antennas. Other antenna operating modes include manual position and velocity, slave, and manual program. The X-Y mounts are capable of tracking through zenith but have a gimbal restriction keyhole near

2-1 453-HDBK-GN the horizon. This restriction is generally oriented north to south on 9-m antennas. Antenna coverage patterns are further restricted at most stations by the surrounding terrain.

2.2.2.2 Range and Range Rate Measurement

a.

General. The 9-m GN S-band Ranging Equipment (MIL and AGO), operating in conjunction with the Multifunction Receivers (MFR) and S-band Exciters (SBE), provides precision range and Doppler measurements for a variety of spacecraft. For vehicles carrying an S-band phase-locked transponder, the ranging equipment will provide unambiguous range data to distances greater than 500,000 km and nondestructive Doppler data for carrier Doppler frequencies up to ±230 kHz. The ranging system employs sinusoidal modulation and extremely-narrow-band processing techniques to provide high- accuracy range data with low received-signal strength.

b.

Range Measurement. Range measurement is performed using a hybrid ranging technique that employs sidetones and a pseudorandom binary-encoded Ambiguity Resolving Code (ARC). The available ranging tones are: 500, 100, 20, and 4 kHz; and 800, 160, 40, and 10 Hz. Any one of the three highest available tones may be selected as the major tone used to obtain range data resolution. During ranging operations, the selected major tone is transmitted continuously, and the lower tones are sequentially applied to resolve range ambiguities. For transmission, the 800-Hz tone is complemented on the high side of the 4 kHz and thus becomes 4.8 kHz. The three lowest tones are transmitted via a double-sideband-suppressed carrier, using the 4-kHz tone as a subcarrier. This action eliminates the modulation components close to the carrier which could degrade carrier acquisition and tracking. The lowest sidetone (10 Hz) gives an ambiguity interval of 0.1 sec (approximately 15,000 km). An ARC having a length of 1023 bits is biphase modulated on the 4-kHz tone. The code bit rate of 160/sec gives a code period of 639,375 seconds, corresponding to an unambiguous range of approximately 958,000 km. However, the range word readout size of 32 bits limits the maximum range readout to 644,000 km. Ranging signal delay is measured with a time increment size of 1 nsec, corresponding to an approximate range increment size of 0.15 m. The 32-bit wide range values are output ten times a second strobed by the 10 pps timing interrupt. Each range value output corresponds to the instantaneous phase delay of the major range tone, ±25 nsec.

c.

Doppler Measurement. The Doppler is originally generated as an arbitrarily biased Doppler signal from the MFR, which is mixed together with reference signals from the exciter, MFR synthesizer, and from the system frequency standard to provide an output Doppler signal with a 70-MHz bias. This output-bias-plus-Doppler signal is translated to a 1.0-MHz bias frequency and then tracked by a PLL, which acts as a phase data multiplier. The resultant bias-plus-multiplied-Doppler signal is then translated to a new bias frequency at two phases separated by 90 degrees. The two phases of this 60-MHz +57.5-kHz data signal are then employed in a high-speed counter for readout and display. The two different phases allow digitizing in 1/4-cycle increments. This 1/4-cycle incrementing, coupled with the prior multiplication by 250, provides an overall resolution (increment size) of 0.001 cycle of the input data and provides a nondestructive on-time readout of the instantaneous accumulated count. This provides

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nondestructive Doppler data with a uniform 0.1-sec sampling interval. Doppler counts can be continuously accumulated for 150 minutes at the maximum Doppler.

d. Rate-aided Tracking. Rate-aided tracking permits use of a narrow bandwidth, range-tone tracking Phase-lock Loop (PLL) with severe signal dynamics. A rate-aid signal is synthesized from the extracted Doppler- plus-bias signal with a fractional error of 1 part in 176,000 or less. As a result, the PLL bandwidth can be very narrow to minimize noise error in the output range data without incurring excessive lag error for

2

range acceleration magnitudes of 150 m/sec or less.

2.2.3 System Configuration

Both AGO and MILA have S-band Tracking Processor Systems (STPSs) for assembling and transmitting metric tracking data and controlling and pointing its associated antenna. Figure 2-1 illustrates a typical 9-meter RER configuration.

2.3 C-band Systems

2.3.1 General

The GN C-band radar tracking systems are amplitude-comparison, monopulse instrumentation systems which measure range, azimuth, and elevation of spacecraft. Included in this discussion are non-GN C-band radars which provide special tracking support for National Aeronautics and Space Administration (NASA) launches.

2.3.2 System Equipment and Capabilities

2.3.2.1 FPS-16 Radar

The FPS-16 radar has a 3.6-m diameter parabolic antenna mounted on an az-el pedestal. The antenna reflector surface consists of wire mesh panels supported by radial trusses. The antenna has a four-horn monopulse feed, supported on a tetrapod, located at the focal point of the antenna reflector.

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2.3.2.2 MIPIR Systems

The FPQ-6, FPQ-14, FPQ-19, and TPQ-18 radars are all classified as Missile Precision Instrumentation Radars (MIPIR) and utilize the same basic electronics configuration. A MIPIR is second generation to the FPS-16 radar and offers several major improvements such as tracking capability to greater distances, greater angle track precision, and rapid detection and lock-on of target. The antenna is an aluminum, parabolic, Cassegrain feed system with a solid surface and a diameter of 8.8 meters mounted on an az-el pedestal. The MIPIR was originally designed in two versions, the FPQ-6 in which the electronic equipment is housed within permanent buildings, and the TPQ-18 housed in modular shelters to enhance transportability of the system. Subsequent changes have resulted in additional configurations and designations as follows: (1) The FPQ-14 offers all FPQ-6 improvements and is computer integrated with the on-axis system;

(2) The FPQ-19 is a former TPQ-18 that has been relocated to a permanent building.

2.3.2.3 FPQ-15 and TPQ-18 (M) Radars

The FPQ-15 and TPQ-18 (M) radars are functionally similar to the FPQ-14 radar but utilize a NIKE Target Tracking Radar (TTR) pedestal.

2.3.2.4 CAPRI and HAIR

The Compact All-purpose Range Instrument (CAPRI) radar evolved from the MIPIR and was designed to fill the specialized needs for range instrumentation radars. The standard CAPRI was delivered with a 12-ft antenna but could be delivered with any size pedestal/antenna configuration. The MTLC is equipped with a 16-ft antenna while the HAIR (VDHC) is equipped with the TPQ-18/FPQ-6 antenna. The transmitter power on both of these systems is 1 MW.

2.3.2.5 The Advanced Research Project Agency, Lincoln C-band Observable Radar (ALCOR)

ALCOR is a high-power, narrowbeam, coherent, and chirped C- band monopulse system capable of simultaneous skin and beacon tracking. It provides azimuth, elevation, range, and range rate data. It has a range accuracy of 0.5 m in narrowband mode, 0.1 m in wideband mode, and an angle accuracy of 0.005 degree. ALCOR has a 12.2-m diameter parabolic antenna with a gain of 54 dB and a beamwidth of 0.3 degree. The peak power output of the ALCOR radar is 4 MW, with an average power of 10 kW.

2.3.3 Radar Characteristics

2.3.3.1

There is some variance in the characteristics of the individual radars even though they have the same model designator. For example, a significant variance in the AN/FPS-16 models is the different antenna size which results in different gain and beamwidth characteristics. Also, some systems have 3.0 MW transmitters in place of the 1.0 MW transmitters. Each of the radars is similar in that the receive systems employ low-noise receivers or parametric amplifiers with a noise figure of about 3.5 dB, they all have digital designate capability, and all are operated in the 5400- to 5900-MHz band. (The AN/FPS-16 1.0 MW transmitter operates in the range of 5450 to

a0389s1.doc 2-5 453-HDBK-GN 5825 MHz; the MIPIR from 5400 to 5900 MHz.) Detailed and up-to-date antenna characteristics are available on-line from the Mission Station Information System (MSIS). (http://msis.gsfc.nasa.gov/)

2.3.3.2

The radars are precision monopulse tracking systems designed specifically for missile range instrumentation. The MIPIRs have greater range tracking capability due to greater antenna size and radiated power. The maximum tracking rate for either system is 20,000 yd/sec. The antenna tracking rates are listed in Table 2-1

Table 2-1. C-band Radar Slew Capabilities

Radar	Azimuth	Elevation
FPS-16 (3.7-m antenna)	750 mils/sec	400 mils/sec
FPS-16 (4.9-m antenna)	800 mils/sec	450 mils/sec
FPQ-6	500 mils/sec	500 mils/sec
TPQ-18	500 mils/sec	500 mils/sec
FPQ-14	5 deg/sec	2.5 deg/sec
ALCOR	10 deg/sec	10 deg/sec
FPQ-15	10 deg/sec	10 deg/sec
FPQ-13	5 deg/sec	2.5 deg/sec

2.3.4 Other Radar Systems

2.3.4.1 General

Although not operating at the C-band frequencies, the ALTAIR and TRADEX systems provide data that is similar to and used in the same manner as that of the C-band radars. These two systems are therefore included in this section.

2.3.4.2 ALTAIR

The ALTAIR system was designed and developed to gather coherent data on reentry vehicles and satellites at very high frequency (VHF) and ultra-high frequency (UHF) frequencies. A general purpose computer within the radar provides real-time control of waveform, PRF, range and angle tracking, maintenance of multiple track files, and recording of target measurements. The 150 foot diameter antenna employs a focal-point VHF feed and a Cassegrainian UHF feed in conjunction with a frequency selective subreflector, giving a monopulse tracking capability at either frequency.

2.3.4.3 TRADEX

The TRADEX system can operate at L-band or S-band. Angle tracking capability exists at L-band only, while range track is possible at either L- or S-band. The system utilizes both uniform train and burst waveforms exhibiting large bandwidth, long pulse duration, and variable burst subpulse spacing to achieve high range and velocity resolution. Also, a Sigma 5 computer provides real-time control of tracking functions, waveform selection and multiplexing, data recording, and system test and calibration.

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2.3.4.4 Configuration and Allocation

The NDOSL (http://fdf.gsfc.nasa.gov/prod_center/) provides radar allocation and station ID information.

2.4 Ranging Equipment

2.4.1 General

Ranging data is provided by various stations by means of STDN Ranging Equipment (SRE) or Receiver-exciter Ranging (RER). The RER equipment is used with Unified S-band (USB) system only, whereas the SRE may be configured for S-band. A station may have one or both of these systems as described in the following paragraphs.

2.4.2 SRE

2.4.2.1 General

SRE ranging in S-band (see Figure 2-2) can be provided by AGO. The Major Range Tone (MRT) frequencies available are 500, 100, and 20 kHz. The MRT is the highest frequency tone used in ranging support and is uplinked continuously. Of these, the 100-kHz and 20-kHz tones can also be used as the Minor Tone (MT), along with 4 kHz, 800 Hz, 160 Hz, 40 Hz, 10 Hz, and the Ambiguity Resolving Code (ARC).

2.4.2.2 S-Band

SRE ranging in S-band only is available at AGO. The configuration is as shown in Figure 2-2, with the 7-m antenna being used for uplink and the 12-m antenna being used for downlink.

2.4.3 RER

The RER configuration, as shown in Figure 2-3, is used with USB systems only. This type of ranging is available from AGO and MIL. The RER utilizes the same MRTs and MTs as the SRE.

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2-9

Figure 2-2. SRE Configuration, S-band

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Section 3. Spacecraft Acquisition Data

3.2 Acquisition Data Formats

3.2.1 General Overview

Acquisition data formats consist of IRV, IIRV, EPV, INP, and Two Line Element (TLE) Message. Acquisition data is available in both low- and high-speed formats. The standard symbol definitions used in the low-speed format descriptions are listed in Table 3-2. In the figures and tables provided for the explanations of formats, all uppercase letters (except CAN and DEL) are fixed characters and are printed as they appear. Lowercase letters are variables which are defined in the tables.

Table 3-2. TTY Symbol Definitions

Symbol	Definition
<	Carriage return
º	Line feed
_	Space
DEL	Delete (ASCII)
CAN	Cancel (ASCII)
-	Figures shift (Baudot)
¯	Letters shift (Baudot)
$	Numeral
-	Sign of parameter

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3.2.1.1	Interrange Vector Message
a.	An IRV contains the position and velocity of a spacecraft at a given time in rotating geocentric coordinates. Checksums are provided for each of the position and velocity components and for the epoch time. In computing these checksums, 0 through 9 have face value; the ampersand (&), used to denote a positive sign, has a value of zero; and the minus (-), used to denote a negative sign, has a value of 1.
b.	The IRV may be transmitted in either five-level format or eight-level TTY code (see Figures 3-1 and 3-2). If the eight-level format is converted to five-level code, the format will convert to that shown for the five-level format; however, if the five-level format is converted to eight-level format, each figure shift will be converted to a cancel code and each letter shift will be converted to a delete code. Refer to Table 3-3 for IRV message body description.
c.	IRVs/IIRVs may be used to compute pointing angle information for any known antenna location. IRVs/IIRVs are not usually restricted to a specific pass but may be used over a limited period of time which is determined by the orbit of the satellite.
3.2.1.2	Improved Interrange Vector Message
a.	The IIRV was implemented on the networks in 1978. The means of transmission may be either low-speed 110-baud teletype or high-speed Nascom blocked format. The IIRV is coded in American Standard Code for Information Interchange (ASCII). Although no parity checks are made on individual characters at Goddard Space Flight Center (GSFC), parity may be required for message switching between Nascom and other communications networks.
b.	All data fields are right justified, with leading zeros added as needed. A positive sign (+) is indicated by an ASCII space, and a negative sign is indicated by a minus (-). The IIRV format is also used for intercenter exchange of acquisition data in Nascom 4800bit blocks. Refer to paragraph 3.2.2.2 for further details.
c.	In addition to containing the spacecraft position and velocity vectors for the given epoch time, the IIRV also contains information about the type of vector as well as additional spacecraft parameters. See Figure 3-3 for the IIRV message body format and refer to Table 3-3 for IIRV message body explanation.

Line 1: < < ≡≡ (optional message text) Line 2: ↓ I R S T C S a a a < < ≡≡↑ Line 3: t 0/ s s s s ∆ m m ∆ d d ∆ n n n n ∆ v < < ≡≡↑ Line 4: s x x x x x x x x x x ∆ c c ∆ s y y y y y y y y y y ∆ c c ∆

s z z z z z z z z z z ∆ c c ≡≡↑ Line 5: s x x x x x x x ∆ c c ∆ s y y y y y y y ∆ c c ∆ s z z z z z z z

∆ c c ∆ h h m m s s s ∆ c c < < ≡≡↓

Line 6: I R E D < < ≡≡↑

KEY: ↑ = figures.

↓ = letters. ∆ = space. < = carriage return. ≡ = line feed.

Figure 3-1. IRV Message Body, Five-level (Baudot) Format

Line 1: _ _ _ _ _ < < ≡≡ (optional message text) D E

Line 2: L I R S T C S a a a < < ≡≡ C A

Line 3: N t Ø s s s s ∆ m m ∆ d d ∆ n n n n ∆ v < < ≡≡ C A

Line 4: N s x x x x x x x x x x ∆ c c ∆ s y y y y y y y y y y ∆ c c ∆

s z z z z z z z z z z ∆ c c < < ≡ ≡
C
A
Line 5:	N s x•	x•		x•	x•	x•	x•	x•	∆ c c ∆ s y•	y•	y•	y•	y•	y•	y•	∆ c c ∆ s z•	z•	z•	z•	z•	z•	z•
	∆ c c ∆ h h m m s s s ∆ c c < < ≡ ≡
Line 6:	I R E D < < ≡ ≡
	KEY:		D
	E = ASCII delete code.
	L
	C
	A = ASCII cancel code.
	N
	∆ = ASCII space.
	< = carriage return.
	≡ = line feed.

Figure 3-2. IRV Message Body, Eight-level (ASCII) Format

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Table 3-3. IRV Message Body Explanation (1 of 2)

Line	Characters	Explanation
1	-------------	Optional message text
2	IRSTCS aaa	Start of message (fixed) Range address. Up to three characters indicating addressee: D = DSN P = PMR S = STDN W = WTR E = ETR Z = WLP A = CSTC K = KMR
3	t 0/ ssss mm dd nnnn v	Vector type: 1 = nominal 2 = in flight 3 = powered flight 4 = simulated Always zero (fixed) Satellite SIC Month of year Day of month Sequence number VID.
4	s xxxxxxxxxx cc s yyyyyyyyyy cc s zzzzzzzzzz cc	Sign of X component X component in feet Checksum for X component Sign of Y component Y component in feet Checksum for Y component Sign of Z component Z component in feet Checksum for Z component. Digits 0 through 9 have face value, the - (minus) sign has a value of 1, and the & (ampersand) sign and spaces have values of 0.

Table 3-3. IRV Message Body Explanation (2 of 2)

Line	Characters	Explanation
5	s x•x•x•x•x•x•x• cc s y•y•y•y•y•y•y• cc s z•z•z•z•z•z•z• cc hhmmsss cc	Sign of X-velocity component X-velocity component in 1/100 ft/second Checksum for X component Sign of Y-velocity component Y-velocity component in 1/100 ft/second Checksum for Y component Sign of Z-velocity component Z-velocity component in 1/100 ft/second Checksum for Z component (see definition in line 4) Epoch time of IRV in hours, minutes, seconds, and 1/10 seconds Checksum of time word (see definition in line 4)
6	IRED	End of message (fixed)

Figure 3-3. IIRV Message Body Format

Table 3-4. IIRV ASCII TTY Message Body Explanation (1 of 2)

Line	Characters	Explanation
1	_ _ _ _	Optional message text.
2	GIIRV a rrrr	Start of message (fixed). Alphabetic character indicating originator of message: ASCII space = GSFC Z = WLP E = ETR L = JPL W = WTR J = JSC P = PMR A = CSTC K = KMR C = CNES Destination routing indicator. Specifies the site for which the message was generated. If for more than one station, this field should contain "MANY."
3	v s 1 c sic (4 chars) bb nnn doy hhmmsssss ccc	Vector type: 1 = Free flight (routine on-orbit) 2 = Forced (special orbit update) 3 = Spare 4 = Maneuver ignition 5 = Maneuver cutoff 6 = Reentry 7 = Powered flight 8 = Stationary 9 = Spare Source of data: 1 = Nominal/planning 2 = Real-time 3 = Off-line 4 = Off-line/mean NOTE Nominal/planning sets cannot be sent to WSGT from the NCC. Fixed one (1) Coordinate system: 1 = Geocentric True-of-Date Rotating 2 = Geocentric mean of 1950.0 (B1950.0). 3 = Heliocentric B1950.0. 4 = Reserved for JPL use (non-GSFC). 5 = Reserved for JPL use (non-GSFC). 6 = Geocentric mean of 2000.0 (J2000.0). 7 = Heliocentric J2000.0. SIC Body number/VID (01-99). Counter incremented for each vector in a set of vector data on a per-station per-transmission basis. Day of year (001 = January 1). Vector epoch in UTC with resolution to nearest millisecond. (The implied decimal point is three places from the right). Checksum of the decimal equivalent of the preceding characters on Line 3: 0 through 9 = face value. Minus (-) = 1. ASCII Space = 0.

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Table 3-4. IIRV ASCII TTY Message Body Explanation (2 of 2)

Line	Characters	Explanation
4	s xxxxxxxxxxxx yyyyyyyyyyyy zzzzzzzzzzzz ccc	Sign character:ASCII Space = positive Minus sign = negative X component of position (meters) Y component of position (meters) Z component of position (meters) Checksum of the decimal equivalent of the preceding characters on Line 4: 0 through 9 = face value Minus (-) = 1 ASCII Space = 0
5	s x•x•x•x•x•x•x•x•x•x•x•x•y•y•y•y•y•y•y•y•y•y•y•y•z•z•z•z•z•z•z•z•z•z•z•z• ccc	Sign character (same as above) X-component of velocity Y-component of velocity Z-component of velocity NOTE All velocity components are in meters/second with resolution to the nearest millimeter/second. The implied decimal point is three places from the right. Checksum of the decimal equivalent of the preceding characters on Line 5: 0 through 9 = face value Minus (-) = 1 ASCII Space = 0
6	mmmmmmmm aaaaa kkkk s rrrrrrr ccc	Mass of spacecraft in kilograms with resolution to 1/10 of a kilogram. The implied decimal point is one place from the right. Contains all zeros when not used. Average spacecraft cross-sectional area in square meters with resolution to the nearest hundredth of a square meter. The implied decimal point is two places from the right. Contains all zeros when not used. Dimensionless drag coefficient. The implied decimal point is two places from the right. Contains all zeros when not used. Sign character for coefficient of solar reflectivityASCII Space = positive Minus Sign = negative Dimensionless Solar Reflectivity coefficient. The implied decimal point is six places from the right. Contains all zeros when not used. Checksum of the decimal equivalent of the preceding characters on Line 6: 0 through 9 = face value Minus (-) = 1 ASCII Space = 0
7	ITERM oooo	End of message (fixed) Originator routing indicator

3.2.1.3 Extended Precision Vector Message

a.

General. The Extended Precision Vector (EPV) message described in this paragraph is the official version of the EPV along with the blocking structure for use with the Nascom 4800-bit block. The inclusion of the EPV in the document does not commit any entity that interfaces with the GSFC Code 450 to use it. Commitment for its use will be by individual Interface Control Documents (ICD) with specific Code 450 organizations. These ICDs should reference this document for the basic structure of the EPV message only and should identify each specific parameter options that is to be exercised. Additional specifics are as follow:

1. The EPV message format is intended to meet high-accuracy orbit propagation requirements. This has been achieved by increasing the precision of the state vector position and velocity components and by including additional force modeling parameters. The means of transmission may be either low-speed 110band teletype or high-speed Nascom blocked format. The EPV is coded in ASCII. Although no parity checks are made on individual characters at GSFC, parity may be required for message switching between Nascom and other communications networks.

2. All data fields are right justified, with leading zeros added as needed. A positive sign (+) is indicated by an ASCII space, and a negative sign is indicated by a minus (-). The EPV format is also used for intercenter exchange of acquisition data in Nascom 4800-bit blocks. Refer to paragraph 3.2.2.2 for further details.

3. See Figure 3-4 for the EPV TTY message body format, and refer to Table 3-5 for the EPV message body explanation.

b.

EPV Message Structure and Protocol.

1. Block Format. The block format used is defined in Figure 3-5. The block is segmented into six distinct parts: network control header, user header 1, time field, user header 2, data field, and error control field.

1. Network Control Header.

1. The Nascom synchronization field, bits 1 through 24, is a 24-bit binary field with the following structure:

2. First bit transmitted 011000100111011000100111 Last bit transmitted
1. The source field, bits 25 through 32, is an 8-bit field that describes the data source. Nascom assigns these codes (refer to NASA Communications Operating Procedures [NASCOP]).

2. The destination field, bits 33 through 40, is an 8-bit binary field that describes the data destination. Nascom assigns these codes (refer to NASCOP).

3. The sequence number field, bits 41 through 43, is a 3-bit field that identifies the sequence in which blocks were transmitted from a source. The range of this cyclic counter is 1 through 7.

453-HDBK-GN

3-9

* 1* 2* 3* 4* 5* 6* 7* 8* 9* 10* 11* 12* 13* 14*15* 16* * ** * *

* * * * ** ** * * * * * * * * *

1-16 17-32 33-48 49-64 65-80 81-96

97-112 113-128 129-144 145-160 161-176

177-192

4753-4768

4769-4784 4785-4800

A0389024.DRW:X:N

N

H

E

E

011000100 1 11 0 11 0 T

00100111				SOURCE CODE
DESTINATION CODE				SEQ No. FORMAT CODE
VEHICLE ID				SPARE
MESSAGE BLOCK TYPE				DESTINATION
S	S	F	BLOCK DATA LENGTH

UTC

BLOCK NUM		MESSAGE BLOCK ID
SPARE	NUM OF BLKS		SPARE	F1	F2	F3	F4	S

MESSAGE OR ACKNOWLEDGEMENT SUBFIELD (4592 BITS)

REMAINDER

AW DO ER RK

****** UH SD ER R1

****** TF II ME EL D

****** UH SD R2

****** DF AI TE AL D

****** EF RL RD ******

Figure 3-5. 4800-bit Block EPV Format

Table 3-5. EPV Message Body Explanation (1 of 5)

Line	Characters	Explanation
1	MT MESSGID S MC CRCR LFLF	Message type (= 03). Message ID. A unique seven-character number used to reference this message. Source (= 0). Message class code: 20 =Routine on-orbit or stationary vector. 25 =Maneuver sequence vector or high-priority on-orbit or stationary vector. Two carriage returns. Two line feeds.
2	GEPV A RRRR CRCR LFLF	EPV message identifier. Alphabetic character indicating originator of message: G = GSFC Z = WLP E = ETR L = JPL W = WTR J = JSC P = PMR A = AFSTC K = KMR C = CNES Destination routing indicator. Specifies the site for which the message was generated. If the message is for more than one station, this field contains "MANY" Two carriage returns Two line feeds
3	V	Vector type: 1 = Routine on-orbit 2 = Special on-orbit update 3 = Spare 4 = Maneuver ignition 5 = Maneuver cutoff 6 = Reentry 7 = Powered flight 8 = Stationary 9 = Spare
	S O C E SIDC BB	Data type: 1 = Nominal/planning 2 = Real-time Origin of coordinate system and reference plane: 1 = Geocentric, Earth equator 2 = Heliocentric, Earth equator 3 = Heliocentric, eclipic 4 = Selenocentric, Earth equator 5 = Selenocentric, Moon equator 6 through 9 = Spares Coordinate system: 1 = Greenwich true-of-date rotating 2 = Greenwich true-of-date nonrotating 3 = Mean-of-1950.0 (B1950.0) 4 = Mean-of-2000.0 (J2000.0) 5 = True-of-date (B1950.0) 6 = True-of-date (J2000.0) 7 = Selenographic. 8 and 9 = Spares. Types of elements only. 1 = Cartesian elements only 2 = Osculating elements only 3 = Both Cartesian and osculating elements SIC Body number of vehicle ID

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Table 3-5. EPV Message Body Explanation (2 of 5)

Line	Characters	Explanation
3	NNN	Counter incremented for each vector in a set of vector data on a pre-station, per-transmission
(cont)	YYYY DOY HHMMSSSSSS S UT1UTC CCC CRCR LFLF	basis. For JSC, each mission is treated as a single transmission. Year. Day of Year. Vector epoch in UTC with resolution to the nearest tenth of a millisecond. The millisecond. The implied decimal point is four places from the right. Sign character: ASCII space = positive Minus sign = negative UT1 = UTC timing coefficient at epoch with resolution to the nearest microsecond. The implied decimal point is six places from the right. This field will contain all zeros when not used Checksum of the decimal equivalents of each of the preceding characters on line 2: 0 through 9 = face value Minus (-) = 1 ASCII space = 0 Two carriage returns Two line feeds
4	S XXXXXXXXXXXXXXXXX S YYYYYYYYYYYYYYYYY S ZZZZZZZZZZZZZZZZZ CCC CRCR LFLF	Sign character: ASCII space = positive Minus sign = negative NOTE X component of position All position components are in kilometers with resolution to the nearest tenth of a millimeter. Sign character: ASCII space = positive Minus sign = negative The implied decimal point is seven places from the right. Y component of position These fields will contain all zeros when not used. Sign character: ASCII space = positive Minus sign = negative Z component of position Checksum. This is the sum of the decimal equivalents of all the preceding characters on line 3: 0 through 9 = face value Minus (-) = 1 ASCII Space = 0 Two carriage returns Two line feeds
5	S x•x•x•x•x•x•x•x•x•x•x•x•x• S y•y•y•y•y•y•y•y•y•y•y•y•y• S z•z•z•z•z•z•z•z•z•z•z•z•z•	Sign character: ASCII space = positive Minus sign = negative NOTE X component of velocity. All velocity components are in kilometers/second with resolution to the nearest tenth of a micron/second. Sign character ASCII space = positive Minus sign = negative The implied decimal point is ten places from the right. These fields will contain all zeros when not used. Y component of velocitySign character: ASCII space = positive Minus sign = negative Z component of velocity

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Table 3-5. EPV Message Body Explanation (3 of 5)

Line	Characters	Explanation
5	CCC	Checksum. This is the sum of the decimal equivalents of all the preceding characters on line 4:
(cont)	CRCR LFLF	0 through 9 = face value Minus (-) = 1 ASCII space = 0 Two carriage returns Two line feeds
6	S OSCSEMIMAJORAXISS S OSCECCENTRIC S OSCINCLINATN CCC CRCR LFLF	Sign character: ASCII space = positive Minus sign = negative Osculating semimajor axis Sign character: ASCII space = positive Minus sign = negative Osculating eccentricitySign character: ASCII space = positive Minus sign = negative Osculating inclination The semimajor axis is in kilometers with resolution to the nearest tenth of a millimeter. The implied decimal point is seven places from the right. The eccentricity is dimensionless with resolution to the nearest 10-10. The implied decimal point is ten places from the right. The inclination is in degrees with resolution to the nearest 10-9 degrees. The implied decimal point is nine places from the right. These fields will contain all zeros when not used. Checksum. This is the sum of the decimal equivalents of all the preceding characters on line 5. 0 through 9 = face value Minus (-) = 1 ASCII Space = 0 Two carriage returns Two line feeds
7	S OSCLONASNODE S OSCARGPERIAP S OSCMEANANOML GRAVITATIONALPARM CCC CRCR LFLF	Sign character: ASCII space = positive Minus sign = negative Osculating longitude of the ascending node. Sign character: ASCII space = positive Minus sign = negative Osculating argument of periapse Sign character ASCII space = positive Minus sign = negative Osculating mean anomaly The longitude of the ascending node, the argument of perigee, and the mean anomaly are in degrees with resolution to the nearest 10-9 degrees. The implied decimal point is nine places from the right. These fields will contain all zeros when not used. Gravitational parameter corresponding to Cartesian and osculating elements in units of kilometers3/second2 with resolution to the nearest 10-5 kilometers3/second2. The implied decimal point is five places from the right. This field will contain all zeros when not used. Checksum. This is the sum of the decimal equivalents of all the preceding characters on line 6: 0 through 9 = face value Minus (-) = 1 ASCII space = 0 Two carriage returns. Two line feeds.

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Table 3-5. EPV Message Body Explanation (4 of 5)

Line	Characters	Explanation
8	MASSMMMM DCSAREA CSBD S DSCALEP SCSAREA S CSUBR F SFLX I	Spacecraft mass in kilograms with resolution to the nearest tenth of a kilogram. The implied decimal point is one place from the right. This field will contain all zeros when not used. Spacecraft reference cross-sectional area for drag calculations in square meters with resolution to the nearest hundredth of a square meter. The implied decimal point is two places from the right. This field will contain all zeros when not used. Dimensionless drag coefficient, CD. The implied decimal point is three places from the right. This field will contain all zeros when not used. Sign character: ASCII space = positive Minus sign = negative Dimensionless drag scaling parameter, d. The effective drag coefficient is given by CD (1 + d). The implied decimal point is five places from the right. This field will contain all zeros when not used. Spacecraft reference cross-sectional area for solar radiation force calculations in square meters with resolution to the nearest hundredth of a square meter. The implied decimal point is two places from the right. This field will contain all zeros when not used. Sign character: ASCII space = positive Minus sign = negative Dimensionless solar reflectivity coefficient, 1 + n, where n is the surface reflectivity of the spacecraft. The implied decimal point is four places from the right. This field will contain all zeros when not used. Solar activity paramater: 1 = Exospheric temperature 2 = F10.7 solar flux. NOTE This field will contain a zero when not used. Exospheric temperature, Tc, at epoch in units of degrees Kelvin with resolution to the nearest unit or of F10.7 solar flux at epoch in units of 10-22 Watts/meter2/Hertz with resolution to the nearest tenth of a unit. The implied decimal place for the F10.7 solar flux is one place from the right. This field will contain all zeros when not used. Geomagnetic activity index type: 1 = Kp 2 = Ap NOTE This field will contain a zero when not used.
	GMGAI CCC CRCR LRLR	Dimensionless geomagnetic activity index, Kp or Ap, at epoch. The implied decimal point is two places from the right. This field will contain all zeros when not used. Checksum. This is the sum of the decimal equivalents of all the preceding characters on line 7: 0 through 9 = face value Minus (-) = 1 ASCII space = 0 Two carriage returns. Two line feeds.
9	---CRCR LFLF	Optional 60-byte free-text line for additional information related to the state vector contained in the EPV message. This field will contain all ASCII blanks when not used. Two carriage returns Two line feeds
10	---CRCR LFLF	Optional 60-byte free-text line for additional information related to the state vector contained in the EPV message. This field will contain all ASCII blanks when not used. Two carriage returns Two line feeds
11	---CRCR LFLF	Optional 60-byte free-text line for additional information related to the state vector contained in the EPV message. This field will contain all ASCII blanks when not used. Two carriage returns Two line feeds

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Table 3-5. EPV Message Body Explanation (5 of 5)

Line	Characters	Explanation
12	ITERM 0000 CRCR LFLF	End of message. Originator routing indicator. Two carriage returns. Two line feeds.
	---	Fill data (3118).

(e) The Nascom format field, bits 44 through 48, is a 5-bit field used to identify the type of data block. The EPV message must have a binary 01011 code in this field.

3. User Header 1.

(a)

The Vehicle ID (VID) field, bits 49 through 56, is an 8-bit field that contains a code identifying the spacecraft to which the message block is related.

(b)

The spare field, bits 57 through 64, is an 8-bit field that contains an all 1's pattern.

(c)

The message block type field, bits 65 through 72, is an 8-bit field that contains a code that defines the specific type of data contained in the block. The EPV message must have a binary 10001100 code in this field.

(d)

The destination code field, bits 73 through 80 is an 8-bit field that is reserved for a destination code that identifies the recipient of the data block and contains the same value as bits 33 through 40.

(e)

Bits 81 and 82 are spare bits and are not used.

(f)

Bit 83 is set to a binary 1, for the full block flag, to indicate that the block data field is completely used, or it is set to a binary 0 to indicate that the data field is less than full.

(g)

The block data length binary field, bits 84 through 96, is a 13-bit field that contains the length, in bits, of user header 2 plus the data portion of the block. If the block is full, this field must contain the binary equivalent of 4624 bits.

1. Time Field. The use of the time field, bits 97 through 144, is optional. If used, it contains NASA PB4 time (refer to X-814-77-64). NCC-generated blocks must always contain a time code in this field. If this field does not contain a PB4 time code, it must be set to all binary 1's.

1. User Header 2.

1. The message block number, bits 145 through 148, is a 4-bit field that contains an incrementing binary counter associated with a unique block ID to place blocks in the proper sequence in a multiblock group. The block count always starts at 1 and increments by 1 for each subsequent block in a multiblock group. A block count of 1 indicates that this block is the only block of a single

2. block message or the first block of a multiblock message. The maximum allowable value in this field is 15.
1. The message block ID field, bits 149 through 160, is a 12-bit field that is used to define a unique message. The message block ID starts with an initial value of 1 and increments by 1 for successive messages. Message block ID assignment is controlled by the message originator. It should not be expected that sequential messages received at a destination will have sequential message block IDs.

2. Bit 161 and 162 contain zeros.

3. The number of blocks binary field, bits 163 through 166, is a 4-bit field that contains the number blocks constituting the message. The maximum number of blocks per message is 15. The number in this field must be the same in all blocks of a message.

4. Bits 167 through 171 contain zeros.

1. Message Block Flags.

1. Five 1-bit flags, bits 172 through 176, are included in the header. These flags must be used to signify an acknowledge request, retransmitted block, acknowledgment enclosed, last block, and one spare bit. A flag set means that the bit equals a binary 1.

2. The acknowledge request flag (F1), bit 172, is set to any message that requires an acknowledgment. The acknowledgment request flag will not be set in an acknowledgment message. An acknowledgment must be sent to the originator on receipt of a completed message having the acknowledgment request flag set. The FDF waits for the acknowledgment of one message before transmitting the next message. The acknowledge request flag is only valid in the first block of a multiblock group.

3. The retransmitted block flag (F2), bit 173, is set in any retransmitted blocks. The original block number and ID are not altered by retransmission.

4. The acknowledgment enclosed flag (F3), bit 174, is set whenever bits 177 through 208 contain an acknowledgment.

5. The last block indicator (F4), bit 175, must be set in the last block of a message and must be 0 in all preceding blocks.

6. Bit 176 is zero.

1. Message Block Data Field. The message block data field, bits 177 through 4768, consists of either the message subfield of 4592 bits or the acknowledgment subfield of 144 bits.

2. Message Subfield. This field consists of 574 8-bit bytes (4592 bits). Each byte contains an ASCII character. ASCII characters have the parity bit (bit 2⁷) set to a zero. The parity bit occurs first in serial transmissions. For example, a message type of 02 (ASCII) appears as follows:

Bit 177 Bit 192

↓ ↓

0 0 1 1 0 0 0 0 0 0 1 1 0 0 1 0

↑ ↑

Parity Parity First bit in serial transmission

8. Acknowledgment Subfield.

(a)

Bytes 23 through 26 are a duplication of bytes 19 through 22 of the last block of the message being acknowledged. This encompasses the data field previously described as follows:

(1)

Block Number.

(2)

Message block ID.

(3)

Spare.

(4)

Number of blocks.

(5)

Spare.

(6)

Block flags.

(b)

Bytes 27 through 33 contain ASCII spaces. Bytes 34 through 40 contain a SUPIDEN code of Z9999ZZ.

9. Error Control Field.

(a)

Bits 4769 through 4776 are spares.

(b)

Bits 4777 and 4778 are used to indicate the detection of errors in a decoded block.

(c)

Bits 4779 through 4800 contain a 22-bit polynomial remainder.

c. EPV Acknowledgment Protocol. On receipt of a complete EPV message requiring an acknowledgment, the receiver will transmit an acknowledgment to the originator in the next block transmission opportunity. The acknowledgment will repeat bytes 19 through 22 of the last block of the message being acknowledged and will always be sent in a separate, standalone message. The acknowledgment block will be an octal message block type (bits 65 to 72) of 113 (4B hexadecimal) for acknowledgments generated by the recipient. If a message is received with flag bit 2 (retransmitted message) set to a 1 and an acknowledgment required (flag bit 1 set to a 1), the receiver will acknowledge receipt of this message in the same manner as previously described. It is the receiver's responsibility to determine if this message has alreay been processed (i.e., same message block ID and source code). If so, the second copy of the message should not be processed.

d.

EPV Acknowledgment Message. The format shown in Table 3-6 will be used for the transmission of an EPV message acknowledgment.

e.

EPV Retransmission Protocol. On failure to receive an acknowledgment within 5 seconds of transmission of the last block of an EPV message, the originator will set the retransmitted block flag (F2) in each block of the message and retransmit the entire message. The first block of the retransmitted EPV message will be transmitted at the next transmission opportunity after any pending acknowledgment. The originator will retransmit all blocks of the EPV message in the order of ascending block sequence number. Retransmitted blocks will retain their original block number, block ID, and type. Failure to receive an acknowledgment for the first retransmission within 5 seconds will result in a second retransmission. Failure to receive an acknowledgment to the second retransmission within 5 seconds will result in an error indication being sent to the responsible operator and the termination of transmission for that particular SUPIDEN and EPV message.

f.

EPVs may be used to compute pointing angle information for any known antenna location. EPVs are not usually restricted to a specific pass but may be used over a limited period of time which is determined by the orbit of the satellite.

Table 3-6. EPV Acknowledgment Message

Item Number	Number of Bytes	Data Item	Range of Values
1	4	Acknowledgment SUBFIELD	Bytes 19-22 from acknowledged message
2	7	Spare	ASCII spaces
3	7	SUPIDEN	Z9999ZZ

3.2.1.4 Internet Predict Message

a.

The INP message contains predicted pointing data for a specific satellite pass and for a specific antenna. The INP body message is preceded by a Nascom header and followed by a Nascom trailer. The INP always contains angle information (see Figures 3-6 and 3-7 and refer to Table 3-7) and may include range information (see Figures 3-8 and 3-9 and refer to Table 3-7) and frequency information (see Figure 3-10.)

b.

The INP must contain at least six data points (and not have more than 50 data points) which have the correct checksum calculations. In computing the checksums, 0 through 9 have face value, the ampersand (&), denoting a positive sign, has a value of 10; the minus (-), denoting a negative sign, has a value of 11.

c.

The standard INP contains 30 points; however, 6 to 50 points are acceptable. The number of dynamic points is a function of request-zero or three and pass geometry-zero to three. The maximum angular difference between successive points should not exceed 5 degrees in the referenced coordinate system of the INP. If the Y axis exceeds

plus or minus 79 degrees (keyhole), the 5-degree requirement can be disregarded. Each INP contains between 0 and 3 pre-acquisition of signal (AOS) and post-loss of signal (LOS) points (i.e., the elevation at the beginning and end of the message may be negative). For long passes, additional INPs are acceptable if the start time of the continued INP is greater than 30 minutes later than the AOS time of the original INP.

d. INPs are issued as Ground Elapsed Time (GET) or Greenwich Mean Time (GMT). An INP generated for GET time generates the points for time elapsed since liftoff with the time for liftoff being considered 000 days, 00 hours, 00 minutes, 00 seconds. INPs generated pre-mission are GET INPs. INPs generated GMT are real-time. GET INP messages are not regenerated unless the liftoff slips more than 30 days.

Line 1: ↑ $ ↓ I N P ↑ $ ∆↓ S E T ∆ a ↑ n n n n, ∆↓ M I S ∆↑ s s s s , ∆S C∆↑ v v , ∆↓ C H ∆↑ c c , ∆↓ S T A ∆ r ↑ i i < < ≡↓ Line 2: S C ∆ X M T ∆↑ f f f f . f f f f f f , ↓ S C ∆ R C V ∆↑ g g g g . g g g g g g , ↓ S T A ∆ X M T ∆↑ h h . h h h h h h ,

↓ R G ∆ M O D ∆↑ r r r r r r < < ≡≡↓ Line 3: e e e ∆↑ y y , d d d , h h m m s s ∆∆∆ ↓ R T L T ∆↑ r r : t t : v v . v < < ≡↓ Line 4: f f f ∆↑ y y , d d d , h h m m s s ∆∆∆↓ R T L T ∆↑ r r : t t : v v . v < < ≡≡↓ Line 5: ∆∆ t t t ∆∆∆ a a a a a ∆∆∆ b b b b b ∆∆↓ C K < < ≡↑ Line 6 to

Line n-1: h h m m s s ∆ a a a a a ∆ b b b b b ∆ c c < <≡↑ Line n: h h m m s s ∆ a a a a a ∆ b b b b b ∆ c c < < ≡≡↑ Line n+1: $ ↓ E N D ↑ $ ∆↓ S E T ∆ a ↑ n n n n , ∆↓ M I S _ ↑ s s s s , ∆↓ S C ∆↑ v v , ∆↓ C H ∆↑ c c , ∆↓ S T A ∆ r ↑ i i < < ≡↓

KEY:

• = Figures

• = Letters ∆ = Space ≡ = Line Feed < = Carriage Return

Figure 3-6. Five-level Coded INP Format with Angles Only

Line 1: $ I N P $ ∆ S E T ∆ a n n n n , ∆ M I S ∆ s s s s , ∆ S C ∆ v v , ∆ C H ∆ c c, ∆ S T A ∆ r i i < < ≡ Line 2: S C ∆ X M T ∆ f f f f . f f f f f f , S C ∆ R C V ∆ g g g g . g g g g g g , S T A ∆ X M T ∆ h h . h h h h h h ,

R G ∆ MO D ∆ r r r r r r < < ≡ ≡
Line 3:	e e e ∆ y y , d d d , h h m m s s ∆ ∆ ∆ R T L T ∆ r r		: t t : v v .v < < ≡
Line 4:	f f f ∆ y y , d d d , h h m m s s ∆ ∆ ∆ R T L T ∆ r	r : t t : v v . v < < ≡ ≡
Line 5:	∆ ∆ t t t ∆ ∆ ∆ a a a a a ∆ ∆ ∆ b b b b b ∆ ∆ CK < <		≡
		C
Line 6 to		A
Line n-1:	h h m m s s ∆ a a a a ∆ b b b b b ∆ c c < < ≡ N
			C
			A
Line n:	h h m m s s ∆ a a a a a ∆ b b b b b ∆ c c < < ≡	≡ N
			D
			E

Line n+1: $ E N D $ ∆ S E T ∆ a n n n n , ∆ M I S ∆ s s s s , ∆ S C ∆ v v , ∆ C H ∆ c c , ∆ S T A ∆ r i i < < ≡ L

KEY: C NOTE

A = Cancel N This is the format when the INP is generated directly in eight level. When converted from an original five-level INP into eight level, the up and down

∆ = ASCII Space arrows in the five-level format (see Figure 3-4) will appear in their corresponding positions in the eight-level format as follows:

< = Carriage Return C D

= Line Feed

↑ = A ↓ = E = N LD E = Delete L

Figure 3-7. Eight-level Coded (ASCII) INP Format with Angles Only

Table 3-7. Explanation of INP Format (1 of 4)

Line	Characters		Explanation
	Fixed	Variable
1	$INP$ SET MIS SC CH	a nnnn ssss vv cc	Start of message SET Alphabetic character specifying generator of data: a. G = FDF/RLT f. W = WTR b. S = FDF/NON-RLT g. P = PMR c. J = JSC h. K = KMR d. L = JPL i. Z = WLP e. E = ETR Predict set number (message sequence number), consisting of four alphanumeric characters and necessary upper and lower case teletype shift charactersMission SIC, consisting of four numeric characters. Cannot be all zeros Spacecraft VID, consisting of two numeric characters (refer to appendix D). Cannot be 00 Channel Channel identification number 01-99 is now defined as: Trajectory Identification Number 01-19 =ON ORBIT - SOURCE OR DESTINATION OF DATA where: 01 = premission nominal (source) 02 = real time (source) 03 = offline (source) 00 = not used 20-79 = launch trajectory variations 80-99 = entry and landing
	STA		Alphabetic character indicating the range for which the message is generated: a. A = CSTC e. P = PMR b. D = DSN f. S = STDN c. E = ETR g. W = WTR d. K = KMR h. Z = WLP Station identification, consisting of two numeric characters. Refer to Appendix C or NDOSL (http://fdf.gsfc.nasa.gov/prod_center/)
2	SC XMT SC RCV STA XMT RG.MOD	ffff.ffffff gggg.gggggg hh.hhhhhh rrrrrr	Spacecraft transmit Spacecraft transmit frequency in MHz Spacecraft receive Spacecraft receive frquency in MHz Station transmit Station transmission frequency in MHz Range modules (ambiguities) Number of range modules subtracted from the range value

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Table 3-7. Explanation of INP Format (2 of 4)

Line	Characters		Explanation
	Fixed	Variable
3		eee	Three alphabetic characters identifying the event used as the start of the message. Valid entries are: AOS: Usually indicates horizon break. SOP: (Start of Predicts); Indicates that the start of the INP does not correspond to a particular event. EMG: (Emergence); Time of spacecraft coming out of occultation with a celestial body CON: (Continuation); Used when message follows another INP which contains data points previous to these (see Note). Used by DOD radars only
	NOTE STDN TDPS-equipped stations cannot process continuation INPs. The TDPS stops processing at the last point in any message and will not automatically process any continuation received. Operator action is required to begin processing of continuation INP.
	RTLT	yy,ddd,hhmmss rr:tt:vv.v	UTC of the event described in eee field. (ddd) cannot be all zeros Round trip light time Round trip light time at time specified by yy,ddd,hhmmss field in hours, minutes, seconds, and tenths of seconds
4	RTLT	fff yy,ddd,hhmmss rr:tt:vv.v	Three alphabetic characters identifying the event used as the end of message. Valid entries are: LOS: Loss of signal due to spacecraft going below station horizon EOP: End of predicts indicates that the end of INP does not correspond to a particular event OCC: Occultation predicts end due to spacecraft going behind a celestial body TBC: Indicates that predicts to be continued in another INP (see Note for line 3). Used by DOD radars only UTC of the event described in fff field. ddd cannot be all zeros Round trip light time Round trip light time at time specified by yy,ddd,hhmmss field in hours, minutes, seconds, and tenths of seconds
5		ttt	NOTE Line 5 entries are column headers for lines 6 through n. The range and Doppler information is optional and may not appear on all INPs. See Figure 3-8 for sample INP with Doppler frequency fields. Indicates GET or GMT

Table 3-7. Explanation of INP Format (3 of 4)

Line	Characters		Explanation
	Fixed	Variable
	CK R	aaaaa rrrr D1 DOP D2 DOP D3XXX tx vco	Up to five alphanumeric characters indicating the coordinate system for angle 1. Valid entries are: a. Eight-level AZI D X30 E L D X85 E L b. Five-level AZI X ↑ 30 ↓ X ↑ 85 ↓ NOTE These entries must correspond respectively to the entries selected for aaaaa field. Checksum NOTE See Figure 3-8 for example of Doppler frequency fields Range Up to four alphabetic characters with appropriate upper and lower case shift indicating the units for range field. Valid entries are: a. KMS _ (kilometers). b. KYD _ (kiloyards). c. NMI _ (nautical miles). d. MCS _ (microseconds). D1 = predicted one-way Doppler frequency measured at the Doppler extractor. R1 = one-way Doppler frequency measured at the receiver Voltage-controlled Oscillator (VCO). S1 = one-way Doppler at S-band. D2 = predicted two-way Doppler frequency measured at the Doppler extractor. R2 = two-way Doppler frequency measured at the receiver VCO. S2 = two-way Doppler frequency at S-band. D3 = three-way Doppler frequency. XXX is the station transmitting to the spacecraft. R3 = three-way Doppler frequency at the receiver VCO. XXX is the station transmitting to the spacecraft. S3 = three-way Doppler frequency at S-band. XXX is the station transmitting to the spacecraft. Doppler frequency of the uplink Signal at the transmitter VCO. NOTE Doppler frequencies in Hertz.

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Table 3-7. Explanation of INP Format (4 of 4)

Line	Characters		Explanation
	Fixed	Variable
6 through n		hhmmss aaaaa bbbbb cc rrrrrrr ddddddddd fffffffff	Six numeric characters specifying the UTC hours, minutes, and seconds of the point. Angle 1 value in 1/100 degree. For X85 and X30, the first character is the sign of the angle where & (ampersand) indicates positive, - (minus) indicates negative. For azimuth, signs are not required, zeros are used to fill unused character positions; i.e., 8.46 deg az = 00846, + 7.31 deg x = &0731 Angle 2 value in 1/100 degree. For ELE, Y85, and Y30, the first character is the sign of the angle where & (ampersand) indicates positive, - (minus) indicates negative. Zeros are used to fill unused character positions; i.e., 7.31 deg Y or EL = &0731 Checksum computed on digits in the aaaaa and bbbbb fields. 0 through 9 carry face value, (&) = 10 and (-) = 11 One-way range in 1/10 units specified in column header (line 5) For D1, D2 and D3 actual Doppler frequency measured at Doppler extractor. For R1, R2, and R3 readings assume a leading 2 before the MSD for S1, S2, and S3 Frequency measurement assumes a leading 1 NOTE All Doppler frequency measurements are in hundredths of Hertz with the decimal point assumed between the second and third digits from the right. The MSD is in megahertz
n+1	$END$		End of message. (The rest of line n + 1 is a repetition of line 1.)

Line 1:	↑ $ ↓ I N P ↑ $ ∆ ↓ S E T ∆ a ↑n n n n , ∆ ↓ M I S ∆ ↑ s s s s , ∆ ↓ S C ∆ ↑ v v , ∆ ↓ C H ∆ ↑ cc , ∆ ↓ S T A ∆ r ↑ i i < < ≡
↓
Line 2:	S C ∆ X M T ∆ ↑ f f f f . f f f f f f , ↓ S C ∆ ↑ R C V ∆ g g g g . g g g g g g , ↓ S T A ∆ X M T ∆ ↑ h h . h h h h h h ↓ ,
	R G ∆ M O D ∆ ↑ r r r r r r < < ≡ ≡ ↓
Line 3:	e e e ∆ ↑ y y , d d d , h h m m s s ∆ ∆ ∆ ↓ R T L T ∆ ↑ r r : t t : v v . v < < ≡ ↓
Line 4:	f f f ↑ y y , d d d , h h m m s s ∆ ∆ ∆ ↓ R TL T ∆ ↑ r r : t t : v v . v < < ≡ ≡ ↓
Line 5:	∆ ∆ t t t ∆ ∆ ∆ a a a a a ∆ ∆ ∆ b b b b b ∆ ∆ ↓ C K ∆ ∆ R ↑ . ↓ r r r r < < ≡ ↑
Line 6 to
Line n-1:	h h m m s s ∆ a a a a a ∆ b b b b b ∆ c c ∆ r r r r r r r < < ≡ ↑
Line n:	h h m m s s ∆ a a a a a ∆ b b b b b ∆ c c ∆ r r r r r r r < < ≡ ≡ ↑
Line n+1:	$ ↓ E N D ↑ $ ∆ ↓ S E T ∆ a ↑ n n n n , ∆ ↓ M I S ∆ ↑ s s s s , ∆ ↓ S C v ↑ v v , ∆ ↓ C H ∆ ↑ c c , ∆ ↓ S T A ∆ r ↑ i i < < ≡
↓
	KEY:
	↑ = Figures
	↓ = Letters
	∆ = Line Feed
	≡ = Line Feed
	< = Carriage Return

Figure 3-8. Five-level Coded INP Format with Range Figure 3-10. Five-level INP Format with Doppler Frequency Field

Figure 3-9. Eight-level Coded INP Format with Range

Line 1: $ I N P $ _ S E T _ a n n n n n , _ M I S _ s s s s , _ S C _ v v , _ C H _ c c , _ S T A _ r i i < < ≡ Line 2: S C _ X M T _ f f f f . f f f f f f , S C _ R C V _ g g g g . g g g g g g , S T A _ X M T _ h h . h h h h h h , R G _ M O D _ r r r r r r < < ≡ ≡ Line 3: e e e _ y y , d d d , h h m m s s _ _ _ R T L T _ r r : t t : v v . v < < ≡ Line 4: f f f↑ y y , d d d , h h m m s s _ _ _ R T L T _ r r : t t : v v . v < < ≡ ≡ Line 5: _ _ t t t _ _ _ a a a a a _ _ _ b b b b b _ _ C K _ _ R . r r r r < < ≡ C Line 6 to A Line n-1: h h m m s s _ a a a a a _ b b b b b _ c c _ r r r r r r r < < ≡ N C A Line n: h h m m s s _ a a a a a _ b b b b b _ c c _ r r r r r r r < < ≡ ≡ N D E Line n+1: $ E N D $ _ S E T _ a n n n n , _ M I S _ s s s s , _ S C _ v v , _ C H _ c c , _ S T A _ r i i < < ≡ L

KEY: C A = Cancel N ∆ = Space ≡ = Line Feed < = Carriage Return D E = Delete L

NOTE This is the format when the INP is generated directly in eight level. When converted from an original five-level INP into eight level, the up and down arrows in the five-level format (see Figure 3-6) will appear in the corresponding positions in the eight-level format as follows: C D ↑ = A ↓ = E N L

Line 5:	∆ ∆ t t t ∆ ∆ ∆ a a a a a ∆ ∆ b b b b b ∆ ∆ ↓ C K _ _ R ↑ , ↓ r r r r ∆ ∆ ∆ D ↑ 1 . ↓ D O P ∆ ∆ ∆ ∆
	D ↑ 2 . ↓ D O P ∆ ∆ ∆ ∆ D ↑ 3 . ↓ X X X X ∆ ∆ ∆ ∆ T X ↑ . ↓ V C O < < ≡ ↑
Line 6 to
Line N:	h h m m s s ∆ a a a a a ∆ b b b b b ∆ c c ∆ r r r r r r r ∆ d d d d d d d d d ∆ d d d d d d d d d ∆ d d d d d d d d d ∆
	f f f f f f f f f < < ≡ ↑

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3.2.1.5 Two Line Element Message

The US Strategic Command (USSTRATCOM) Element/Bulletin contains the classical orbital elements for an orbiting object. The orbital elements are contained in a two-line (also referred to as a two-card) element message. This message is sent via the five-level TTY code (see Figure 311 and refer to Table 3-8) from USSTRATCOM. Where required, GSFC can convert this to eight-level.

SOM ( ( ( ( ( ∆↓↓↓↓↓↓ < < ≡

Line 1: ↑ 1 ∆ s s s s s ↓ c ∆↑ i i l l l v v v ↓∆↑ y y d d d . d d d d d d d d ∆ s ↑ .

mmmmmmmm ∆↑ S m¨ m¨ m¨ m¨ m¨ - m ∆ S↑ d d d d d - d ∆↑ e ∆ n n n n c ↓↓↓↓ < <

Line 2: ↑ 2 ∆↑ s s s s s ∆↑ i i i . i i i i ∆ r r r . r r r r ∆ e e e e e e e ∆↑ p p p . p p p p ∆ a a a . a a a a

∆ r r . r r r r r r r r n n n n n c

Key: ( = Parenthesis ∆ = Space

• = Letters

• = Figures < = Carriage Return ≡ = Line feed

Figure 3-11. USSTRATCOM Two-line Orbital Element Format

Table 3-8. Explanation of USSTRATCOM Two-line Orbital Element Format

Line	Characters	Explanation
SOM 1	((((( sssss c iilllvvv yy ddd.dddddddd S.mmmmmmmm S.mmmmm-m S.ddddd-d e nnnn c	Fixed (start of message code) Satellite number Classification U = unclassified C = confidential S = secretInternational Designator ii = launch year ill = launch number of year vvv = piece of launch Epoch year of message Epoch day and fraction of day First time derivative of the mean motion or ballistic coefficient (depending on ephemeris type). Revolutions per day 2 or meters 2 per kilogram. S = minus sign if appropriate plus signs are not used. Second time derivative of mean motion. Revolutions per day 3. Decimal point assumed between S and first m. S = minus sign if applicable. This field will be blank if not applicable. BSTAR drag term if GP4 general pertubations theory was used; otherwise, this field will be radiation pressure coefficient. S = minus sign if applicable. Ephemeris type: Specifies ephemeris theory used to produce the elements. 0 = mean inertial, 1 = osculating inertial. Element number Checksum: Modulo 10
2	sssss iii.iiii rrr.rrrr eeeeeee ppp.pppp aaa.aaaa rr.rrrrrrrr nnnnn c	Satellite number. Inclination in degrees. Right ascension of ascending node in degrees. Eccentricity (decimal assumed at beginning of field). Argument of perigee in degrees. Mean anomaly in degrees. Mean motion (revolutions per day). Revolution number at epoch. Checksum: modulo 10.

3.2.2 Acquisition Data Transmission

3.2.2.1 General

Acquisition data is transmitted by the FDF or JSC to GN ground stations via NISN. This data is generated in eight-level ASCII teletype format by FDF. The acquisition data is implanted into 4800-bit blocks by a Conversion Device (CD) and transmitted to the Tracking Data System (TDS) where it is converted to eight-level ASCII teletype format and sent to the tracking sites and range stations. Projects also send acquistion data via FTP and e-mail.

3.2.2.2 4800 Bit Block

Vectors are exchanged between NASA centers and external agencies. The vectors are formatted as IIRVs or EPVs and transmitted in 4800-bit blocks. The packing into blocks for IIRVs is illustrated in Figures 3-12 and 3-13; unique IIRV packing will be controlled by ICDs. The packing into blocks for EPVs is illustrated in Figures 3-14 and 3-15.

MSB MSB LSB 1 18

A0389007.DRW:X:N

LS

1472 DATA BITS (1BLOCK MESSAGE)

3152 FILL BITS

Figure 3-12. Illustration of IIRV Data Words Packed into the Data Field of the 4800-bit Block Format

FIRST BIT TRANSMITTED (BIT 1, NASCOM HEADER)

(WORD 1) G = =1 I (WORD 2)

(WORD 3) I = =1 R (WORD 4)

(WORD 5) V = =1 SP (WORD 6)

EVEN PARITY ON BIT 8

32-BIT BLOCK ERROR CONTROL FIELD

16 BITS

A0389008.DRW:X:N

Figure 3-13. Illustration of IIRV ASCII Characters Packed into the 4800-bit Block

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MSB MSB LSB LSB 1 18

4488 DATA BITS (1 BLOCKMESSAGE)

Figure 3-14. Illustration of EPV Data Words Packed Into the Data Field of the 4800-bit Block Format

FIRST BIT TRANSMITTED (BIT 1, NASCOM HEADER) (WORD 1) 0

(WORD 17) G =(WORD 19) P =

16 BITS

A0389010.DRW:X:N

3 (WORD 2)

WORDS 1 AND 2 INDICATE MESSAGE TYPE. IN THIS EXAMPLE, IT IS A "03"

= E (WORD 18) = V (WORD 20)

(WORD 574)

Figure 3-15. Illustration of EPV ASCII Characters Packed into the 4800-bit Block

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3.2.3 Acquisition Data Processing

GN sites use STPS, TTCP, and MPA for acquisition data processing. Reception of data is handled as follows (refer to the current tracking Software Support Instruction (SSI) for current version of operational software being used):

a.

STPS.

1. The on-site STPS systems automatically receive and store acquisition data.

2. The STPS can accept Interrange Vector (IRV), Improved Interrange Vector (IIRV), and Internet Predict (INP) messages.

1. When the STPS is on, and the Update acq function is not being performed, the following apply:

1. Any incoming acquisition message whose epoch or first-point time is more than 24 hours old from the current Universal Time Coordinated (UTC) will not be written to the disk. An operator message will list the acquisition message received but not saved.

2. All disk-resident acquisition data whose epoch or first-point time is less than 24 hours old from current UTC is tagged for deletion and removed from the availability listing when new acquisition messages of the same type (IIRV, IRV, or INP) and identical Support Identification Code/Vehicle Identification Code (SIC/VID) and VS (CH) fields are received.

3. All disk-resident acquisition data whose epoch or first-point time is less than 30 minutes (plus or minus) of the epoch or first-point time of the incoming acquisition data is tagged for deletion and removed from the availability listing by the incoming data, providing the SIC/VID and VS (CH) fields are identical.

4. If the INP Time Check Override (ITOR) function is selected, all INPs regardless of epoch time or first-point are accepted and automatic purging is deactivated.

b.

TTCP.

1. The TTCP can receive and hold one IIRV message, as follows:

(a)

The TTCP determines the geometric validity of the message and writes the message to the disk.

(b)

The existing message is deleted and replaced by the incoming message.

c.

MPA. The MPA can accept IRV, IIRV, and INP messages.

3.2.4 LTAS

High-speed acquisition data is utilized by some stations for launch and Shuttle landing support. The Launch Trajectory Acquisition System (LTAS) replaced the Launch Trajectory Data System (LTDS) in 1978.

Although originally adopted only as an acquisition data source for STDN, expanded support has mandated LTAS format for some tracking data requirements. Therefore, in that respect, it may be considered as dual function. The Central Computer Complex (CCC) can use almost any type of tracking data to generate LTAS, but the WLP Impact Prediction (IP) must have 2.4-kb/sec Minimum Delay Data Format (MDDF) data as an input. FDF, MIL, WPS, and the WLP radar can receive and process LTAS data. The 2.4-kb/sec LTAS data is transmitted Least Significant Bit (LSB) first and is composed of 240-bit blocks containing smoothed, best source, E, F, and G data. In addition, 16 of the 240 bits contain a pattern which allows the onstation processors at LTAS-equipped stations to synchronize on the incoming LTAS data and use it as an acquisition source. See Figure 3-16, and refer to Table 3-9 for an explanation of the format. The LTAS has three standard operational configurations as follows:

a.

Cape Canaveral Launches. The CCC at Cape Canaveral receives real-time RADAR tracking data from the Eastern Test Range (ETR) and GN, and converts it to LTAS format for transmission to the WLP, and MIL tracking stations and to Flight Dynamics Facility (FDF).

b.

Space Shuttle Landings.

1. Edwards AFB Landings. The CCC receives real-time radar tracking data from the WTR, Pacific Missile Test Center (PMTC), and Air Force Satellite Test Center (AFFTC), and converts it to LTAS format for transmission to the west coast tracking stations and to FDF.

2. Cape Kennedy Landings. ETR and WTR radars transmit real-time tracking data to CCC where it is converted to LTAS and transmitted to the MIL tracking station and to the FDF.

c.

Ariane Launches. The WLP C-band transmits 2.4-kb/sec MDDF data to the IP system which converts it to LTAS format for transmission to GSFC and to Kourou, French Guiana. .

Table 3-9. Explanation of Launch Trajectory Acquisition System 2400-b/sec Format* (1 of 3)

Bit No.	Description
1-13	Satellite ID Code (binary)
14-17	Vehicle ID Code (binary)
18-26	Day of year (binary)
27-30	Format type (binary) = 0000 for LTAS
31-34	Time of Day - Tenths of seconds (binary - LSB = 0.1 sec)
35-51	Time of Day - Seconds (binary - LSB = 1.0 sec)
52-60	Site ID (refer to appendix C, table C-2)
61-87	E-position component (meters)
88	Sign for E (0 = positive) (1 = negative. When negative, bits 61-87 will be 2's complement.)
89-90	PSC (Position Scale Code: value by which all position components should be multiplied if the field length is exceeded): 00 - x 1 01 - x 10 10 - x 103 11 - x 1010
91-117	F-position component (meters)
118	Sign for F (0 = positive) (1 = negative. When negative, bits 91-117 will be 2's complement.)

Table 3-9. Explanation of Launch Trajectory Acquisition System 2400-b/sec Format* (2 of 3)

Bit No.	Description
119-120	00 - x 1 01 - x 10 (All other scales are invalid)
*30 bits = 1 word; bit No. 1 = first bit transmitted.
121-147	G-position component (meters)
148	Sign for G (0 = positive) (1 = negative. When negative, bits 121-147 will be 2's complement.)
149	Optical Track Bit (OTB) (always = 0)
150	PTF (Plus Time Flag) (1 = using plus time)
151-164	F-velocity component (meters/second)
165	Sign for F 0 = positive (1 = negative. When negative, bits 151-164 will be 2's complement.)
166-179	E-velocity component (meters/second)
180	Sign for E 0 = positive (1 = negative. When negative, bits 166-179 will be 2's complement.)
181	L liftoff 1 = liftoff has occurred
182	P plunge mode 1 = plunge
183-184	P/W (Pulse Width) 00 - 1.0 µsec 01 - 2.4 µsec 10 - 5.0 µsec 11 - 10.0 µsec
185	RFI (Refraction correction) (0 = out)(1 = in)
186	DI (Droop) (0 = out) (1 = in)
187	PO (Paramp) (0 = off) (1 = on)
188	RO (Radiation) (0 = off) (1 = on)
189	LO (0 = Single LO) (1 = Dual LO)
190	B/S (Beacon/Skin) (0 = skin) (1 = beacon)
191	T (Track bit) (0 = off) (1 = on)
192	Q (Quality bit) (0 = bad) (1 = good)
NOTE When LTAS is generated by the BDA IP, bit 191 signifies the Angle bit (A) and bit 192 signifies the Range bit (R).
193-195	Mode (Bit No. 193 194 195) 0 0 0 = manual 1 0 0 = autotrack 0 1 0 = computer drive 1 1 0 = on-axis orbital 0 0 1 = on-axis powered flight 1 0 1 = on-axis coast 0 1 1 = autotrack coast
196-209	G-velocity component (meters/second)

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Table 3-9. Explanation of Launch Trajectory Acquisition System 2400-b/sec Format* (3 of 3)

Bit No.	Description
210	Sign for G (0 = positive) (1 = negative. When negative bits 196-209 will be 2's complement.)
211-217	Checksum (see Note)
218-224	Spares.
225-240	Sync bits. Bits 225-240 will have the following patterns: 0-0-0-1-1-0-1-0-0-0-0-1-1-0-1- 0 on one message and 0-0-0-1-1-0-1-0-0-0-0-0-0-1-0-1 on the next.
NOTE LTAS 2400-b/sec checksum algorithm: a. The first 210 data bits are treated as fourteen words of 15 bits each. These words are summed, treating them as positive integers, in an accumulator capable of handling a 19-bit positive integer sum. b. This sum is split up into three parts: the most significant 7 bits, the next most significant 6 bits, and the least significant 6 bits, and these three words are summed, treating them as positive integers, in an accumulator capable of handling an 8-bit positive integer sum. c. The least significant 7 bits of these sums become the checksum.
*30 bits = 1 word; bit No. 1 = first bit transmitted.

* 15*14* 13* 12* 11* 10* 9* 8* 7* 6* 5* 4* 3* 2* *1 * BIT NO. VID

SIC (13 BITS)

* 30* 29* 28* 27* 26* 25* 24* 23* 22* 21* 20* 19* 18* 17* 16* BIT NO.

FORMAT TYPE DAY OF YEAR (4 BITS)

*

45* 44* 43* 42* 41* 40* 39* 38* 37* 36* 35* 34* 33* 32* 31* BIT NO. TIME OF DAY

*

60* 59* 58* 57* 56* 55* 54* 53* 52* 51* 50* 49* 48* 47* 46* BIT NO.

SITE IDENTIFICATION

*

75* 74* 73* 72* 71* 70* 69* 68* 67* 66* 65* 64* 63* 62* 61* BIT NO. E POSITION COMPONENT (METERS)

*

90* 89* 88* 87* 86* 85* 84* 83* 82* 81* 80* 79* 78* 77* 76* BIT NO.

PSC S

*

105* 104* 103* 102* 101* 100* 99* 98* 97* 96* 95* 94* 93* 92* 91* BIT NO. F POSITION COMPONENT (METERS)

*

120*119* 118* 117* 116* 115* 114* 113* 112* 111* 110* 109* 108* 107* 106* BIT NO.

VSC S

*

135* 134* 133* 132* 131* 130* 129* 128* 127* 126* 125* 124* 123* 122* 121* BIT NO. G POSITION COMPONENT (METERS)

*

150* 149* 148* 147* 146* 145* 144* 143* 142* 141* 140* 139* 138* 137* 136* BIT NO.

PTF OTB S

* 165* 164* 163* 162* 161* 160* 159* 158* 157* 156* 155* 154* 153* 152* 151* BIT NO.

S F (METERS/SECOND)

* 180* 179* 178* 177* 176* 175* 174* 173* 172* 171* 170* 169* 168* 167* 166* BIT NO.

S E (METERS/SECOND)

* 195* 194* 193* 192* 191* 190* 189* 188* 187* 186* 185* 184* 183* 182* 181* BIT NO.

MODE Q T B/S

LO

RO PO DI RI P/W P L

* 210* 209* 208* 207* 206* 205* 204* 203 202* 201* 200* 199* 198* 197* 196* BIT NO.

S G (METERS/SECOND)

* 225* 224* 223* 222* 221* 220* 219* 218* 217* 216* 215* 214* 213* 212* 211* BIT NO.

SPARES CHECKSUM

* 240* 239* 238* 237* 236* 235* 234* 233 232* 231* 230* 229* 228* 227* 226* BIT NO.

S

SYNC BITS * * * * * * *

A0389013.DRW:X:N

Figure 3-16. Launch Trajectory Acquisition System 2400-b/sec Data Format

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3.3 Slaving Systems

3.3.1 Intrasite Slaving System

3.3.1.1

The Intrasite Slaving System (ISS), composed of slaving switch panels and a slaving junction box, provides a flexible method of slaving one onstation antenna to another. It allows any automatic-tracking type antenna to operate as a leader to drive one or more antennas without affecting the accuracy of the leader or introducing instabilities into the servo systems of either the leader or the slaved antennas.

3.3.1.2

Figure 3-17 illustrates the basic leader-to-slave configuration of the ISS. A slaving system synchro Control Transformer (CT) is mounted on each axis of those types of antennas which are slaves/leaders, and on each of the slave-only antennas. A slaving system synchro-transmitter (TX or CX) is also mounted on each axis of the automatic-tracking (leader) type antennas.

3.3.1.3

All leader and slave systems are interfaced through the slaving junction box. Each slave system also has a slaving switch panel to indicate the availability of leader-type angles. The slaving switch panel has indicators and controls for each of the interfaced systems. An indicator for the associated system will light on the leader system's slaving switch panel when the leader system is being used as a slave source. The upper portion of a split-screen Pushbutton Indicator (PBI) will light on the slave systems slaving switch panel for each leader system that is ready to be used as a slave source. To slave to the desired leader, press the split-screen PBI for the appropriate system. The lower portion of the split-screen PBI will light to indicate that the slave system is indeed slaved to the desired leader. The slaving capabilities of the GN stations with ISS are listed in Table 3-10.

Table 3-10. ISS Slaving Capabilities

Station	Antenna
AGO	12-m * 12-m TDPS* 9-m S-Band* 9-m STPS* 11-m RX/TX * 7-m L-Band RX SATAN TX 7-m RX/TX
MIL	9-m S-band No. 1* 9-m S-band No. 2* TELTRAC, 18 element STPS 1 and 2*
WPS**	STPS 1 and 2* S-band 7.3-m 1 and 2 Rx S-band 6-m TX 9-m S-band*
* These systems can be leaders in the slaving configuration. The others can only be followers. ** WLP indicates Wallops Island tracking radars, WPS indicates Wallops Island orbital tracking (TM/ranging).

SLAVE ANTENNA SOURCE 1, 2, OR 3

SOURCE 1, 2, OR 3

Figure 3-17. Intrasite Slaving System Block Diagram

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Section 4. Tracking Data Formats and Reduction Algorithms

4.2 Low-speed Tracking Data Formats

4.2.1 General

This paragraph describes the formats used for transmission of low-speed tracking data which is sent from the station via FTP (post-pass) or teletype circuits. Definitions of the various teletype code symbols are the same as those for acquisition data and are presented in Table 3-2.

Tracking data is sent in eight-level ASCII teletype format by tracking sites and range stations to the NISN Tracking Data System (TDS). The TDS implants the TTY-received tracking data into 4800-bit blocks. This tracking data is transmitted in that 4800-bit block format to a NISN Conversion Device (CD) for Internet Protocol/User Datagram Protocol (IP/UDP) encapsulation and transmission to the FDF or JSC.

4.2.2 Universal Tracking Data Format

4.2.2.1 Introduction

The Universal Tracking Data Format (UTDF) is used by all systems configured with a TDF, or else a STPS, ITCP, & MPA. The means of transmission is FTP (post-pass) from the TDF UTDF files and TRS systems may be via either a low-speed 110-baud TTY circuit or a high-speed 9.6kb/sec circuit, depending on mission requirements. One sample of data contains 75 bytes and is the same for both low- and high-speed transmission. Table 4-1 describes the contents of a data sample, and Table 4-2 describes the system-unique modes required for bytes 49 and 50.

4.2.2.2 TTY Transmission

UTDF data transmitted via teletype from the TPS is at a sample rate of one sample per 10 seconds. When this Low-sample Rate (LSR) data is required by JSC or FDF, NISN packs the data into 4800-bit blocks for transmission. This procedure is discussed in paragraph 4.3.3.

4.2.2.3 FTP Transmission

UTDF data transmitted post-pass via FTP is sent in files consisting of only the 75-byte UTDF frames. No larger block is used.

Table 4-1. Universal Tracking Data Format (1 of 3)

Byte	Format	Description
1	0D(16)	Fixed
2	0A(16)	Fixed
3	01(16)	Fixed
4 to 5	ASCII	Tracking data router: 4141 = AA = GSFC 4444 = DD = GSFC 4646 = FF = GSFC/France (CNES) 4848 = HH = GSFC/Japan 4949 = II = GSFC/Germany (ESRO) 4A4A = JJ = GSFC/JSC
6	Binary	Last two digits of current year
7 to 8	Binary	SIC
9 to 10	Binary	VID
11 to 14	Binary	Seconds of year
15 to 18	Binary	Microseconds of second
19 to 22	FOC	Angle 1; X or az
23 to 26	FOC	Angle 2; Y or el (Angle 2 byte/bit format is the same as for bytes 19-22.)
NOTE For bytes 19-22/23-26, convert angle data to decimal form. Angle data is given in fractions of a circle. To express raw angle in degrees, multiply decimal angle by 8.381903173 x 10-8 (360 degrees divided by 232). When the STPS is initialized as WPS S08 or S37, these bytes will read zero.
27 to 32	Binary	RTLT in 1/256 nsec (MSB = 524288 ns; LSB = 0.00390625 ns)
33 to 38	Binary	Bias Doppler, counts of: 240 MHz + 1000 fd' LSB = 1 count
39 to 40	Binary	AGC (an integer: −150 AGC 8192 −50 = dBm ) Note: AGC field not used by systems with TDF
41 to 44	Binary	Transmit frequency information in 10's of Hz
45	Discrete	MSD = antenna size (xmit) as follows: 0(16) = less than 1 m 1(16) = 3.9 m 2(16) = 4.3 m 3(16) = 9 m 4(16) = 12 m 5(16) = 26 m 6(16) = TDRSS ground antenna 7(16) = 6 m 8(16) = 7.3 m 9(16) = 8.0 m A(16) through F(16) = spares

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Table 4-1. Universal Tracking Data Format (2 of 3)

Byte	Format	Description
45		LSD = antenna geometry (xmit) as follows:
(cont)		0(16) = az-el 1(16) = X-Y(+X-south) 2(16) = X-Y(+X-east) 3(16) = RA-DEC 4(16) = HR-DEC 5(16) through F(16) = spares
46	Binary	Pad ID (xmit) Link ID (refer to Appendix C)
NOTE If S-band and 3 way, zeros are output. If S-band and 2 way, good data is output. If VHF and 3 way, zeros are output. If VHF and 2 way, byte 45 is 0 and 46 is pad ID.
47 48	Discrete Binary	Antenna size (rcv; refer to byte 45) Pad ID (rcv refer to byte 46)
NOTE If VHF, byte 47 is 0 and 48 is pad ID. If S-band, good data is output.
49-50	Discrete	Mode-system unique (refer to Table 4-2)
51	Discrete	Data validity by bit: 8 = (MSB) sidelobe (1 = sidelobe) 7 = destruct R• (1 = destruct) 6 = refraction correction to R, R• (1 = corrected)
		5 = refraction correction to angles (1 = corrected) 4 = angle data correction (1 = corrected) 3 = angle valid (1 = valid) 2 = R• valid (1 = valid)1 = (LSB) R valid (1 = valid)
52	Discrete	MSD= frequency band, as follows: 1(16) = VHF 2(16) = UHF 3(16) = S-band 4(16) = C-band 5(16) = X-band 6(16) = Ku-band 7(16) = visible 8(16) = S-band uplink/Ku-band downlink 9(16) through F(16) = spares

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Table 4-1. Universal Tracking Data Format (3 of 3)

Byte	Format	Description
52 (cont)	Discrete	LSD = data transmission type, as follows: 0(16) = test 1(16) = spare 2(16) = simulated 3(16) = resubmit 4(16) = RT (real time) 5(16) = PB (playback) 6(16) through F(16) = spares
53 to 54	Discrete	MSD = tracker type: Byte 53, bits 8 through 5: 0(16) = C-band pulse track 1(16) = SRE (S-band and VHF) or RER 2(16) = X-Y angles only (data acquisition antenna) 3(16) = Spare 4(16) = SGLS (AFSCF S-band trackers) 5(16) = Spare 6(16) = TDRSS 7(16) = STGT/WSGTU 8(16) = TDRSS TT&C 9(16) through F(16) = spares Byte 53, bit 4: 1 = last frame of data (not used by systems with TDF) Byte 53, bits 3 through 1 and eight bits of byte 54: 11 bits for transmission rate (positive indicates the binary seconds between samples up to a maximum of 1023; negative indicates the 2's complement of the number of samples per second).
55 to 72	Spare
73	04(16)	Fixed.
74	0F(16)	Fixed.
75	0F(16)	Fixed.

Table 4-2. System-unique Modes

System	Bits	Description
C-band	1 (LSB)	0 = beacon, 1 = skin
	2	0
	4,3	00 = autotrack 01 = program track 10 = manual 11 = slaved
	16 to 5	Rest spares
NOTE If for WPS S08 or S37, will always read slaved. If GRT S55 or S57, will always read slaved and angles valid bit will be set when in steptrack mode.
SRE	1 (LSB)	0 = coherent 1 = noncoherent
	2	0 = secondary, 1 = primary
	4,3	See C-band
	6,5	00 = not used 01 = 1-way 10 = 2-way 11 = 3-way
	8,7	01 = lowest sidetone 10 Hz
	10, 9	00 = not used 01 = major tone 20 kHz 10 = major tone 100 kHz 11 = major tone 500 kHz
	13 to 11	Autotrack MFR, 1 to 6 (binary) (0 = unknown) (MFR not applicable for TDF-equipped systems)
	16 to 14	Range MFR, 1 to 4 (binary) (0 = unknown) (MFR not applicable for TDF-equipped systems)
SRE - VHF	2,1	Not used
	4,3	See C-band
	6,5	Not used
	10,7	See SRE

4.2.2.4 Data Reduction Algorithms

The following processes are used to convert UTDF to the decimal form of data, whether transmitted via FTP, TTY or 9.6-kb/sec circuits:

a.	Observed Angles. To process, convert angle data to decimal form. To express angle data in degrees, multiply by 8.381903173 x 10-8 .
	NOTE
	For X-Y angles only, subtract 360 degrees whenever the converted
	value exceeds 180 degrees.
b.	Observed Range.	The observed measurement is Round Trip Light Time (RTLT) in
	units of 1/256 nsec and is time-tagged at receive time. To process, convert range data to decimal form. In units of length, the range is R (T) = (c/512) 10-9 Rr (T)
	where: c = speed of light in units of length/sec
	Rr = raw range value in decimal form
c.	Observed Range Rate. The Doppler measurement is the cumulative cycle count of the
	Doppler frequency plus a 240-MHz bias frequency.		It is time tagged at the time of
	cycle counter reading. To process, convert Doppler data to decimal form. The observed
	average range rate is:
	R•N ()T0 -N ()T-1⎡⎢ﾣ ⎤⎥ﾦ -c -2.4 x 108T0 (units, same as "c") =

()

2f_TKM T0 - T-1

where:	c	=	speed of light.
	fT	=	transmit frequency in Hertz.
	K	=	240/221 for S-band, or 1 for VHF, 880/749 for X-band.
	M	=	1000 for S-band and VHF, 250 for X-band.
	N	=	cumulative Doppler-plus-bias counter reading
	T0, T-1	=	time of present and previous Doppler count, respectively

4.2.3 USSTRATCOM B3 Type 2 Radar Data Format

The USSTRATCOM B3 Type 2 data format consists of FPQ-6 radar data originating at WPS and transmitted to USSTRATCOM in real-time via NISN. The USSTRATCOM B3 Type 2 format is illustrated in Figure 4-1 and described in Table 4-3.

(NASCOM TTY HEADER) BT (CR/CR/LF/LF) UNCLAS (CR/CR/LF/LF) ) ) U n n n i 2 t t t v v v v v d d d h h m m s s 0 0 0 x e e e e e e 0 a a a a a a a 0 r r r r r r r 2 0 c $ $

Figure 4-1. USSTRATCOM B3 Type 2 Radar Data Format

Table 4-3. Explanation of USSTRATCOM B3 Type-2 Radar Data Format

Character Number	Character	Explanation
	BT CR/CR/LF/LF UNCLAS CR/CR/LF/LF	(Break) (2 carriage returns and 2 line feeds) Unclassified message (2 carriage returns and 2 line feeds)
1-2	))	Start of message (fixed)
3	U	Unclassified (fixed)
4-6	nnn	000 to 999 = message number; assigned sequentially to observation messages by the reporting station
7	i	Report indicator: 3 = First line 4 = Body line 5 = Last line 8 = Data off track
8	2	Observation type = AZ/EL/R (fixed)
9-11	ttt	Station number: 439 = WLPS FPQ-6
12-16	vvvvv	Satellite number; NORAD classification number.
17-28	dddhhmmss000	Time of observation: DDD = day of year HH = hour of day MM = minutes SS = seconds 000 = fractional part of seconds (fixed)
29-36	xeeeeee0	Elevation: X = sign EEEEEE = elevation in degrees. Decimal point implied between second and third digits from left 0 = weight indicator (fixed)
37-44	aaaaaaa	Azimuth: AAAAAAA = azimuth in degrees. Decimal point implied between third and fourth digits from the left 0 = weight indicator (fixed)
45-53	rrrrrrr20	Range: RRRRRRR = range in kilometers. Decimal point implied between the fourth and fifth digit from the left 2 = exponent (fixed at 2, indicates position of decimal point) 0 = weight indicator (fixed)
54	c	Checksum; sum (Modulo 10) of characters 4 through 53
55-56	$$	End of message

4.2.4 46-character Radar Data Format

4.2.4.1 General

The 46-character C-band format is illustrated in Figure 4-2 and described in Table 4-4. Each line of data is preceded by a line feed and two figure shifts or cancel codes and is followed by a carriage return. Each line is transmitted in the sequence indicated by the character (second column of Table 4-4). The azimuth, elevation, and range data are in octal form with the most significant character transmitted first. This data is transmitted to JSC for Shuttle support. It is packed into 4800-bit blocks at NISN prior to transmission, as illustrated in Figure 4-3.

RR↓< ≡ (start of message)

≡↑↑ v s s z d h h m m s s a a a a a a a e e e e e e e r r r r r r r r r d o y s i c c m < ≡↑ # ↓ (end of message)

Key: ↓ = letter shift (5 level) or delete code (8 level) < = carriage return ≡ = line feed

↑ = figure shift (5 level) or cancel code (8 level) # = pound sign

Figure 4-2. C-band 46-character Radar Data Format

Table 4-4. Explanation of Radar 46-character Format

Number	Characters	Explanation
(SOM) 1 2 to 3 4 5 to 6 7 8 9 10 11 12 13 14 15 to 21 22 to 28	RR ↓ < ≡ ↓ ≡ --v ss z d h h m m s s aaaaaaa eeeeeee	Low-speed data router where: RR = DD for GSFC only = JJ for JSC and GSFC = KK for GRTS/JSC/ETR = II for GSFC/Germany Letter shift (5 level) or delete (8 level) Carriage return Line feed Letter shift (5 level) or delete (8 level) Line feed Figure shifts (5 level) or cancel (8 level) Vehicle ID (0 to 9) Station ID (refer to appendix C) RADAR ID (0 to 9) Data validity (0 = invalid/2 = valid) Time (UTC) hours (tens) hours (units) minutes (tens) minutes (units) seconds (tens) seconds (units) Azimuth angle where: 15 = (0 to 1) 16 to 21 = (0-7) LSB = 0.0006866455 deg Elevation angle where: 22 = (0 to 1) 23 to 28 = (0 to 7) LSB = 0.0006866455 deg
29 to 37 38 to 40 41 to 44 45 46 (EOM)	rrrrrrrrr doy sicc m CR ≡ ↑ # ↓	Range where: 29 = (0-1) 30 to 37 = (0-7) LSB = 1.7859375 meters UTC day of year (000 to 366) Support ID code (0000 to 9999) Mode where: 1 = beacon 2 = skin 3 = test 4 = last frame Carriage return Line feed Figure shift (5 level) or cancel (8 level) Pound sign Letter shift (5 level) or delete (8 level)

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4.2.4.2 DOD C-band Trackers

The DOD C-band trackers are capable of correcting data for tropospheric and ionospheric refraction upon request. The onstation refraction corrections are documented in STDN No. 601 (mission Network Operations Support Plan [NOSP]). STDN stations do not apply a refraction correction. Transponder delay is always applied onstation.

4.2.4.3 Data Reduction Algorithm

Appropriate conversions are noted in the format description.

4.3 High-speed Tracking Data Formats

4.3.1 General

This paragraph describes the types of high-speed tracking data formats transmitted from the GN. LTAS, which is also used as a tracking data format, is described in paragraph 3.2.4. Refer to appendix E for station format transmission capabilities.

This data is sent in 240-bit blocks by launch-support tracking sites to the NISN TDS. The TDS implants the received high-speed tracking data into 4800-bit blocks. This tracking data is transmitted in that 4800-bit block format to a NISN CD for IP/UDP encapsulation and transmission to the FDF or JSC.

4.3.2 Minimum Delay Data Format

4.3.2.1 General

The MDDF transmit capability exists at WGS and MIL S-band and on the WGS radar. Each frame of data contains 240 bits. See Figure 4-4 for MDDF format, and refer to Table 4-5 for an explanation of the format.

Table 4-5. Explanation of MDDF Format (1 of 2)

Bit	Description
1-13	SIC (binary)
14-17	VID (binary)
18-26	Day of year (binary)
27-30	Format type (binary) 27 0 28 1 29 1 30 1
31-34	Time of day (binary-tenths of seconds) BIT VALUE = 31 0.1 32 0.2 33 0.4 34 0.8
35-51	Time of day (binary-seconds) BIT VALUE = 35 1 36 2 51 65536
52-60	Site ID (Refer to Appendix C, Table C-2) NOTE To decode the angle fields (bits 61-79/80-98), convert to decimal and multiply by the granularity (0.0006866455 degree). If the result is between 180 and 360 degrees, the angle is negative (except for the azimuth reading on az-el trackers) and can be determined by subtracting 360 degrees from the result.
61-79	Angle 1 (X or azimuth) (LSB = 0.0006866455) (binary)
80-98	Angle 2 (Y or elevation) (LSB = 0.0006866455) (binary)
99-123	Range (LSB = 1.7859375 m) (binary)
124-171	Doppler (counts of 240 MHz + 1000 fd) (LSB = 1 cycle)*
172-173	One-, two-, or three-way data: 172 173 0 0 = 1-way 1 0 = 2-way 1 1 = 3-way
174	R/T (real/test) 1 = real data
175-176	Geo (antenna geometry): 175 176 0 0 = az-el 1 0 = (X-Y) (+X = south) 1 1 = (X-Y) (+X = east)
177-180	Toggle bits: 177 178 179 180 On one frame: 1 0 1 1 On next frame: 0 1 0 0
181	L (liftoff); 1 = liftoff has occurred
182	P (plunge mode); 1 = plunge
183-184	P/W (Pulse width): 183 184 0 0 = 1.0 m sec 1 0 = 2.4 m sec 0 1 = 5.0 m sec (0.25 sec for WFC radars) 1 1 = 10.0 m sec (0.5 sec for WFC radars)

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Table 4-5. Explanation of MDDF Format (2 of 2)

Bit	Description
185	RI (refraction correction) 0 = out, 1 = in
186	DI (droop) 0 = out, 1 = in
187	PO (paramp) 0 = off, 1 = on
188	RO (radiation) 0 = off, 1 = on
189	LO 0 = single LO, 1 = dual LO
190	B/S (beacon/skin) 0 = skin, 1 = beacon
191*	T (track bit) 0 = off, 1 = on
192**	Q (quality bit) 0 = bad, 1 = good
193-195	Mode: 193 194 195 0 0 0 = manual 1 0 0 = autotrack 0 1 0 = computer drive 1 1 0 = on-axis orbital 0 0 1 = on-axis powered flight 1 0 1 = on-axis coast 0 1 1 = autotrack coast
196	R (range) 1 = range good, 0 = range bad
197	A (angles) 1 = angles good, 0 = angles bad
198	DOP (Doppler) 1 = Doppler good, 0 = Doppler bad
199	DD (destruct Doppler) 1 = destruct Doppler
200	LFI (last frame indicator) 1 = last frame
201-224	Cyclic Redundancy Code (CRC)***
225-240	Sync bits will have the following pattern: 0-0-0-1-1-0-1-0-0-0-0-1-1-0-1-0
* The on-track bit (No. 191) is present under the following conditions (or equivalent): a. All three servos are in auto mode; i.e., have no designation/acquisition source (including manual) selected. b. Radiation ON. c. ADRAN/DIRAM range verified. d. Angle control ADRAN/DIRAM (not autotrack). e. ADRAN/DIRAM not coast. ** Q-bit ON corresponds to a 6-dB or greater signal-to-noise ratio plus a valid on-track bit (bit 191). ***The TRACQ Program (SCAN Control No. 13-601.X) does not generate a CRC Code for MDDF data. Zeros are output in these positions.

4.3.2.2 Cyclic Redundancy Code

a.

A Cyclic Redundancy Code (CRC), formerly called a polynomial error code, is used to protect the data in the MDDF. The data that is to be protected is used to create a polynomial D(X), which is then divided by a known polynomial G(X) of degree 22. The remainder polynomial from this division is then used to determine the 22-bit CRC.

b.

The polynomials used have coefficients in F2, the field with two elements. The following truth tables summarize the necessary facts about F2:

Addition Table

	0	1
0	0	1
1	1	0

Multiplication Table

	0	1
0	0	0
1	0	1

F2 = 0,1

For example; F(X) = X² + X + 1 and G(X) = X² + 1 are two polynomials with coefficients in F2. Performing the indicated operations on the coefficients in F2, the following is found:

F(X) + G(X) = X and F(X); G(X) = X⁴ + X³ + X + 1

c. As a simple example of CRCs, consider a data block of eight bits to have three-bit CRC, and generating the polynomial G(X) = X³ + X + 1. Suppose the following eight-bit serial data stream was to be sent:

+--------------¾ 10011110 ¦ +-------First bit transmitted

d. Generate D(X) = X10 + X7 + X6+ X5 + X4, where the coefficients are the data bits in transmitted order, and the leading power of X is 8 + 3 - 1 = 10. Doing the division, the following is found:

X¹⁰ + X⁷ + X⁶ + X⁵ + X⁴ = (X⁷ + X⁵ + X) (X³ + X + 1) + (X²+ X).

R(X) = X² + X and the CRC is 110 (the coefficients).

e. The eleven bits transmitted are:

10011110 110 Data) (CRC)

First bit sent

f. Computer implementation of this division is as follows:

1. Append three zeros to the data to get the correct polynomial: 10011110000.

2. From left to right, exclusive OR the 4-bit pattern for G(X) at each successive 1:

10011110000

1011 101110000 1011

10000 1011 110

Since an LSB transmit of the data is used, a small change in the algorithm is necessary.

3. By bit flipping the pattern for G(X), D(X) and working right to left, the correct CRC is generated in a form that is directly transmitted as follows:

00001111001 1101 000011101 1101 00001 1101 011 with a transmitted CRC of 110 (transmitting LSB first).

g. Bits 201 through 224 are the CRC in the MDDF. A 22-bit CRC is used, and the two additional bits are flags that could be used by intervening hardware decoders to indicate that the CRC did not check. Initially, they are zeros.

4.3.3 High-speed Universal Tracking Data Format

4.3.3.1 General

High Sample Rate (HSR) tracking data is available from GN trackers. The means of transmission is either FTP (post-pass) or a high-speed 9.6-kb/sec circuit. Its transmission by NISN utilizes the 4800-bit block structure shown in Figure 4-5 and defined in Table 4-6. Each block is segmented into five distinct fields as shown in Figure 4-5. These fields contain the following:

a.

Network Control Header, Bytes 1 through 6. Used to identify the start and type of message of each 4800-bit data block.

b.

User Header, Bytes 7 through 12. Contains the information required by the user to route and process the data contained in the block. Note that bits 65-72 (refer to Table 4-6) define the type of tracker and the type of UTDF (LSR or HSR) data.

c.

Time Field, Bytes 13 through 18. This field is set to logical ones in TDRS data. This is an optional NASA entry-binary time code (reception time of first bit in the data field bit 145).

d.

Data Field, Bytes 19 through 596, GSTDN/JPL. The data field contains from one to seven tracking data samples (refer to Table 4-1 for description of a sample). If the 9.6 kb/sec circuits are being utilized for transmission of LSR data (refer to paragraph 4.2.2), the sample rate will be 1/10 sec. If HSR data is being transmitted, the sample rate may be 10/sec, 1/sec, 1/10 sec, or 1/60 sec. The portion of the data field between the end of the last tracking data sample and the first bit of the error control field is filled by a fixed pattern of 311 octal.

e.

Data Field, Bytes 550 through 579, JPL/DSN 26-m Subnet Only. If HSR data and sample rate is 1/sec, 1/10 sec, or 1/60 sec, these bytes contain Tracking Data Residuals (O-Cs) and Time. If sample rate is 10/sec, these bytes will contain fill data (octal 311).

f.

Error Control Field, Bytes 597 through 600. This field is set to logical ones for TDRSS data. NASA uses this field to determine whether bit errors occurred during the transmission of the block.

Table 4-6. 4800-bit Block Structure, Tracking Data (1 of 2)

Bit Number	Description
Network Header
1 to 24	Synchronizaton: A bit pattern identifying beginning of block sync pattern = 011 000 100 111 011 000 100 111 (30473047 octal) (627627 hex)
25 to 32	Source: Geographic source of the data (note)
33 to 40	Destination: Geographic destination of the data (note)
41 to 43	Block Sequence Number: Identifies the sequence in which the source transmits the block. Set to 0 in DSN format.
44 to 47	Format Code: Identifies general type of data C-band = 0110 TDPS = 1110 tracking data TDRSS = 0101 TDPS UPDATE DATA = 0001
48	Block Size: 1 = 4800 bit block/0 = 1200 bit block
User Header
NOTE 1. This header field varies depending on user requirements. Two user headers will be detailed; the user header transmitted by STDN and the user header transmitted by TDRSS. 2. Refer to Digital Data Source/Destination and Format Code Handbook for the NISN Nascom Message Switching System, GSFC-NISN-COM-99-001 , or NASA Communications Operating Procedures, Volume 1, 452-006 for these codes. NISN controls these documents.
STDN User Header
49 to 56	Source Circuit ID: Identifies, by circuit, the geographic source of the data (refer to Table 4-7). If a DSN rate of 1 sample/sec, 1/10 sec, or 1/60 sec is selected, this field is overwritten with 001 octal.
57 to 60	Source Circuit Sequence No. Sequence number assigned on a circuit basis.
61	Spare
62 to 64	Block Sequence No. Same information as Block Sequence No. in the Network Header. This number is repeated here because the Network Header Block Sequence Number will be overwritten when the data is retransmitted from GSFC to JSC. Set to 0 when DSN sample rate is used.
65 to 72	Message Type: 251 octal = S-band HSR tracking data. (A9 hex) 106 octal = MDDF tracking data (46 hex) 211 octal = S-band LSR tracking data. (89 hex) 367 octal = S-band LSR (TTY) tracking data (F7 hex) 370 octal = C-band 46 character tracking data. (F8 hex) 360 octal = TDRSS user and TT&C tracking data (hex F0)
73 to 80	Destination: Geographic destination of the block. Same as destination in Network Header.
81 and 82	Spares
83	Full Block Flag: Set = 0 if fill pattern contained in the data field. Fill pattern = 311 octal.
84 to 96	Data Length: Binary count of number of actual data bits in the block. Fill bits not included. When using STDN rate of 10:1 or DSN rate of 1:1, this should be 4200. When using DSN rate of 1:10 or 1:60, it should be 600.

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Table 4-6. 4800-bit Block Structure, Tracking Data (2 of 2)

Bit Number	Description
TDRSS User Header
49 to 52	Block Sequence No.: Block sequence number within a message
53 to 64	Message Identity: 4095
65 to 71	Fixed at 0001111
72 to 75	Message Type. Fixed at 0001
76 to 80	Protocol Control Flags
81 and 82	Spares
83	Full Block Flag. (No fill data.)
84 to 96	Message Field Size: The number of data bits in the data field, excluding fill data (600 for sample rates of 1/10 sec and 1/60 sec, and 4200 for sample rates of 1/10 sec and 1/sec)
Time Field
97 to 144	TDRSS Data: Time field set to logical ones STDN/NASA: This is an optional binary time code that indicates the time of reception of the first data bits (bit 145). DSN: Tracking Data Processor System (TDPS) tracking data transmitted to JPL contains a time tag in a modified PB4 format:
NOTE In the Parallel Binary Time format, PB1 is to milliseconds resolution and PB4 to microseconds. The modified PB4 format merely sets all microsecond bits to zero, in effect changing the PB4 value to the PB1 resolution.
97 to 98	Parity, set to zero.
99 to 107	Day of year, binary.
108 to 134	Milliseconds of day.
135 to 144	Microseconds, set to zero.
NOTE UTDF sample rate selection determines the contents of this field. A rate of 10:1 sec sets field to zeros. Other rates insert the PB4 format.
Data Field
145 to 4768	Tracking Data. From 1 to 7 UTDF frames of data at a 10/sec, 1/sec, 1/10 sec, or 1/60 sec sample rate. If less than 7 frames of data in the data field then a FILL data pattern (311 octal) will be inserted following the data. Bits 4345 through 4400 and Bits 4641 through 4768 will always contain fill data. Bits 4401 through 4640 will contain Tracking Residuals and Time if HSR data, and transmitting station is GDS, RID, or NBE, and sample rate is other than 10/sec; if sample rate is 10/sec then these bits will contain fill data also. (The data field is transmitted sequentially in 8-bit with the most significant byte transmitted first. STDN transmits the LSB of each byte first, while TDRSS transmits the MSB of each byte first. See Figure 4-7 for layout of packing of HSR data.) Block Error Control. This field set to 1's for TDRSS
4769 to 4776	STDN. Spare.
4777	STDN Polynomial Status Flag. Indicates the polynomial check passed/failed at GSFC.
4778	STDN Polynomial Status Flag. Indicates the polynomial check passed/failed at JSC.
4779 to 4800	Polynomial Reminder. This results from encoding the block at the source.

4.3.3.2 Construction of 4800-bit Block

Regardless of whether UTDF is LSR (refer to paragraph 4.2.2) or HSR (refer to paragraph 4.3.3), when transmitted on 9.6-kb/sec circuits, it is first packed into 4800-bit blocks. Each data sample (shown in Figure 4-6) is packed into a data field as shown in Figure 4-7. This data field will contain up to 7 samples of 75 bytes each, plus fill, plus tracking residuals (JPL only), and when complete, will become that portion of the block labeled DATA in Figure 4-5. The remainder of the block structure is as outlined in the preceding paragraph. The 4800 bit block is transmitted sequentially in 8-bit with the MSB of each byte first, except for the synchronization bits and the source circuit ID bits. TDRSS transmits the MSB of each byte first. See Figure 4-7 for a layout of the packing of the HSR data.

4.3.3.3 Data Reduction

UTDF transmitted on the 9.6-kb/sec lines is converted to decimal form in the same manner as teletype transmission. The algorithms used in this process are discussed in paragraph 4.2.2.4.

Table 4-7. Source Circuit ID Codes (Octal)

GN Site	Line 1	Line 2	Line 3	9.6 kb/sec Track
SPARE	030	031	032	NA
AGO	040	041	042	NA
SPARE	064	065	066	067
MIL	004	005	006	007
PDL	110	NA	NA	NA
SOCC	134	135	136	NA
VANS	NA	NA	NA	151
WSSH	220	NA	NA	NA
SPARE	153	154	NA	NA
GSFC Interfaces
TTY/4.8 (Track)	377
FDF	377
NCC	377
POCC	377
NOTE For GSFC interfaces with source circuit codes of 377, the source circuit sequence number will always contain all ones.

Section 5. Computer Program Applications