PDS_VERSION_ID = PDS3
RECORD_TYPE = STREAM
OBJECT = TEXT
PUBLICATION_DATE = 2010-12-15
NOTE = "Description of the Station Raw Tracking
data set contained in the Lunar
Reconnaissance Orbiter (LRO) Radio
Science data archive volume."
END_OBJECT = TEXT
END
Station Raw Tracking Data
=========================
The Station Raw Tracking Data provides the LRO Flight
Dynamics Facility with the data required to support tracking of the
orbiter and generation of orbit and mission products. The Universal
Tracking Data Format are in a binary form; one datum contains
seventy-five (75) bytes of information. The following processes are
used to convert utF to the decimal form of data:
a. Observed angles - to process, convert angle data to decimal form.
To express angle data in degree, 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)10-9Rr(T) where:
c = speed of light in units of distance/sec
Rr = raw range value in decimal form
c. Observed Range Rate - The doppler measurement is the cumulative
cycle count of 1000 times 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:
RĀ(T0) = -c [A-2.4x108]/B (units, same as 'c')
where: c = speed of light
A = N(T0) N(T -1)/[T0 - T-1]
B = 2ftKM
ft = transmit frequency in Hertz
K = 240/221 for S-band
M = 1000
N = cumulative Doppler-plus-bias counter
reading
T01 T-1 = time of present and previous
Doppler count, respectively.
Additional details and relevant information, such as station ID tables,
can be found in the Archive Volume SIS (/DOCUMENT), as well as in the
INST.CAT (/CATALOG).