6.8
Command Antenna
Exhibit B
The command subsystem is capable of using either the omnidirectional antenna, or the high gain communications antenna.
6.8.1 Omni Antenna Pattern
The command omnidirectional antenna radiation pattern shall be toroidal The with maximum radiation essentially normal to the satellite spin axis.
to antenna beamwidth in a plane containing the spin axis shall be such as provide for necessary command control during the complete mission.
6.9
Command Capacity
There shall be a minimum of 191 commands for the spinning section and 255 for the despun section.
6.10 Ranging System
29 A
The telemetry command subsystem shall be capable of being used ranging transponder throughout all mission phases including stationkeeping via the omnidirectional and communications antenna at an uplink flux density of -80 dBW/m2 and -90 dBW/m2, respectively.
respectively. Capability shall exist to determine range from the phase delays in a series of tones transponded by the satellite.
6.10.1 Ranging Accuracy
2
For reference purposes only, the ranging system including the TT&C earth station equipment shall be capable of a range measurement accuracy of ±150 meters and a minimum ambiguity resolution of ±500 km.
6.10.2 Range Tone Frequencies
The spacecraft design shall allow the following precision frequency, harmonically related tones, which are derived from a 1.000 Milz source, to be used sequentially for the range measurements during transfer and drift orbit:
1)
=
Tone A 1.000 MHz ÷ 36 =
27.777 KHz
2)
Tone B = Tone A ÷ 7 = 3.968 KHz
3) Tone C = Tone B ÷ 14 = 0.283 KHz
4)
Tone D = Tone C + 8 =
35.4 Hz
(Tone D is modulated on Tone B for transmission.)
6.10.3 Stationkeeping
The TT&C
stationkeeping
subsystem in combination with the ACS shall be capable of the communications
either
±0.05° N-S
and
at E-W
position.
better than satellite to an accuracy
or the 105.5° E 116° E longitude orbital
B-24
1
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