Timing recovery in the channel processor of a digital group demodulator
Abstract
In future generations of satellites, digital group demodulators will be used to regenerate frequency division multiple access (FDMA) / quadrature phase shift keying (QPSK) signals on board the satellite and convert them to a time division multiplexed stream for the return link. The group demodulator consists of a digital trans-multiplexer which separates out the individual FDMA/QPSK signals and a bank of per-channel processors which perform timing and carrier recovery for each channel. Timing recovery is examined within the channel processor of the group demodulator. The timing is adjusted using a finite impulse response filter that acts as an adaptive delay and also decimates the sample sequence to obtain a baud rate sequence from which decisions on the symbols can be made. The design of this adaptive rate control filter is discussed with emphasis on the influence of the tap length and filter response function in acquisition and tracking performance.
- Publication:
-
Electrical and Computer Engineering, Volumes 1 and 2
- Pub Date:
- 1991
- Bibcode:
- 1991ecev.confS....S
- Keywords:
-
- Adaptive Filters;
- Demodulators;
- Fir Filters;
- Onboard Data Processing;
- Satellite Communication;
- Signal Processing;
- Digital Techniques;
- Time Division Multiplexing;
- Timing Devices;
- Electronics and Electrical Engineering