Abstract: The gain of a recursive integrator is controlled so as to be adaptive to the quality of a received signal by comparing the magnitude of its emphasized information component with a reference voltage and controlling the gain of the integrator's feedback delay path in accordance with the difference between the peak value of the emphasized information component and the reference voltage. As a result, when the signal to noise ratio of the input signal is high, the gain can be reduced, so that the recursive loop will adapt quickly to changes in a multipath profile.

Abstract: In a digital data recovery receiver, an optimal (in the Maximum likelihood sense) estimate of Es/No (dB) is obtained by the following mechanism. First, over a prescribed symbol span of N symbols, for each of 2.sup.B-1 -1 quantization bins, respectively associated with 2.sup.B-1 threshold levels used by a B-bit resolution analog-to-digital converter to digitize a received signal, the number of times that the received signal is quantized with respect to that level is counted. Each count total is divided by the number N of symbols in the span, to obtain plural ratios, respectively representative of probalities of symbol pseudo error rate over the symbol span. Using these ratios, respective Es/No (dB) values are derived from stored pseudo error relationships, each of which is associated with a respective one of the 2.sup.B-1 -1 quantization bins and defines the probability of symbol error rate in terms of Es/No (dB).

Abstract: A hybrid despread and demodulation receiver for low symbol rate communications employs a passive (SAW) matched filter to remove a "short" coding portion of a composite spreading code that has been used to spread the data signal. The composite spreading sequence is formed by multiplying different length coding sequences, thereby obtaining an overall signal processing operator the duration or symbol span of which is sufficient to maintain a high signal processing gain, but is considerably longer than can be processed using a practical sized passive (e.g. SAW) filter design. The design of the receiver takes advantage of the fact that the relatively short sequence can be despread using a practical SAW structure and is comprised of a hybrid signal processor, the front end of which contains a compact SAW matched filter and the downstream end of which is implemented using analog processing components.