Start Date
4-1984 8:00 AM
Description
The Wide Dynamics Demodulator (WDD) provides the capability to demodulate digital data received from an accelerating spacecraft, even during the high Doppler rates caused by booster engine firing.
The WDD is constructed around an internal microprocessor that receives highlevel commands from the external system computer, interprets them to select the optimum tuning, filtering, and operating modes, and reports status back to the external computer. The WDD will acquire a 35 MHz input signal with up to j^4200 Hz offset from the estimated frequency, and the frequency may be changing by as much as +8.2 Hz per second and at a rate of up to 30.6 Hz/second 2 . The PN code is searched first, followed by Costas-loop carrier search. After carrier lock, the loop changes from first-order to third-order, allowing frequency changes of up to jO 0,300 Hz from nominal at a rate of j765 Hz per second. Data rates from 100 b/s to 300,000 b/s may be processed.
Tracking Accelerating Spacecraft Signals with the Wide Dynamic Demodulator.
The Wide Dynamics Demodulator (WDD) provides the capability to demodulate digital data received from an accelerating spacecraft, even during the high Doppler rates caused by booster engine firing.
The WDD is constructed around an internal microprocessor that receives highlevel commands from the external system computer, interprets them to select the optimum tuning, filtering, and operating modes, and reports status back to the external computer. The WDD will acquire a 35 MHz input signal with up to j^4200 Hz offset from the estimated frequency, and the frequency may be changing by as much as +8.2 Hz per second and at a rate of up to 30.6 Hz/second 2 . The PN code is searched first, followed by Costas-loop carrier search. After carrier lock, the loop changes from first-order to third-order, allowing frequency changes of up to jO 0,300 Hz from nominal at a rate of j765 Hz per second. Data rates from 100 b/s to 300,000 b/s may be processed.
Comments
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