Evolution Of The GPS Navigation Payload - Stanford Center for ...
Evolution Of The GPS Navigation Payload - Stanford Center for ...
Evolution Of The GPS Navigation Payload - Stanford Center for ...
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10/22/09<br />
A Key Part of the AUTONAV Function is Provided By a<br />
VHF Crosslink<br />
CROSSLINKS AND AUTONAV<br />
– Each <strong>GPS</strong> IIR Satellite has a<br />
Redundant Crosslink Transponder<br />
Data Unit (CTDU) supplying a dual<br />
function <strong>for</strong> AUTONAV<br />
• Supplies a Precise Inter-Satellite<br />
Ranging Signal<br />
• Exchanges the AUTONAV State<br />
Vector between satellites<br />
– <strong>The</strong> CTDU is a Time Division<br />
Multiple Access (TDMA)<br />
Frequency Hopped Spread<br />
Spectrum Communication System<br />
incorporating a 5 mChip/s<br />
Pseudorandom Code. Output<br />
power is 108 Watts.<br />
RF<br />
Output<br />
RF<br />
Input<br />
Modulator/<br />
PA Driver<br />
Receiver<br />
AFS Switch<br />
Digital<br />
Signal<br />
Processor<br />
TT&C<br />
Interface<br />
Power<br />
Converters<br />
CTDU Configuration Utilizes Dual Frequency <strong>for</strong><br />
Elimination of Plasmasphere Delays<br />
Use or disclosure of this in<strong>for</strong>mation is subject to the restrictions on the Title Page of this document.<br />
PA<br />
RF Converters/<br />
IF Subsystem<br />
Frequency<br />
Synthesizer<br />
Modulator/<br />
PA Driver<br />
MDU<br />
Interface<br />
Data<br />
Control<br />
10<br />
10.23 MHz<br />
X1 Epoch<br />
Analog Telemetry<br />
Digital Telemetry<br />
28 V
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