Fundamental limits to synchronization and tracking
Abstract
This is the Final Report for a study which was conducted over an 18 month period, and encompasses three tasks, as follows: Task 1 Acquisition Search: Establish fundamental limits to the rate of search for time/frequency acquisition, with particular application to high processing gain spread spectrum systems. The effects of phase noise and platform dynamics, such as Doppler rate of change due to acceleration, are to be studied. The potential improvement offered by technologically advanced devices, e.g., matched filters, is to be examined. An objective is to show how matched filter processing gain may be trade for acquisition time; Task 2 Tracking for Coherent and Noncoherent Modulation: A comparison of coherent and noncoherent modulation techniques (BPSK versus MFSK, for example) is to be made with respect to tracking performance limits set by phase noise and platform dynamics. It is generally believed that noncoherent modulation is superior when phase noise effects are significant. However, this is offset by the inherent E sub b/N sub o advantage (approximately 3 dB) of coherent modulation schemes. The framework for the study is generic pseudonoise and frequencyhopping spreadspectrum antijam modulation and coding techniques; and Task 3 Combined Coding and Tracking, extends the delayed bit estimation algorithm for uncoded BPSK to a convolutionally encoded BPSK and QPSK signal. A comparison between noncohernent, differentially coherent, and partially coherent systems leads to the conclusion that partially coherent operation, sharing power between data and a pilot component, has approximately the same threshold and is a much simpler implementation than the delayed bit estimation algorithm.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 July 1984
 Bibcode:
 1984STIN...8521504C
 Keywords:

 Decoding;
 Digital Techniques;
 Electromagnetic Noise;
 Frequency Synchronization;
 Incoherence;
 Matched Filters;
 Modulation;
 Polystation Doppler Tracking System;
 Radar Tracking;
 Signal Encoding;
 Signal To Noise Ratios;
 Acquisition;
 Algorithms;
 Amplification;
 Carrier Frequencies;
 Computerized Simulation;
 Dynamic Characteristics;
 Frequency Hopping;
 High Frequencies;
 Jamming;
 Monte Carlo Method;
 Rates (Per Time);
 Synchronism;
 Electronics and Electrical Engineering