Abstract: In an arrangement for evaluating an incoming speech signal to enable the selection of a receiver with the best quality speech signal over a substantial range of input signal levels, the logarithm of the input signal is processed in an absolute value and filter circuit to obtain the envelope of the logarithm of the input waveform which is next applied to a peak detector and to a valley detector. The output voltage of the peak detector is proportional to the logarithm of the speech peaks, and the output voltage of the valley detector is proportional to the logarithm of the noise floor voltage during the speech pauses. The peak and valley detector output voltages are applied to an arithmetic circuit which provides a voltage that is a function of the ratio of the speech peaks to the intersyllable noise floor.

Abstract: A system, which selects the most desired signal from similar signals provided by two or more radio receivers, includes a separate arrangement of a signal quality detector, a signal selection gate, and a comparison circuit for each of the similar signals. Each detector provides an output signal level indicative of the quality of the particular one of the similar signals to which it is responsive. The comparison circuits determine from the various detector output signal levels the better signal among the similar signals and provide a control signal to the selection gate in the arrangement including the detector indicating the better signal. The selection gate in the arrangement responsive to the better signal in response to the control signal passes the better signal out of the system. A priority bus is common to all of the above-mentioned arrangements responsive to the respective similar signals.

Abstract: A system, which selects the most desired signal from similar signals provided by two or more radio receivers, includes a signal quality detector and a comparator for each of the signals. Each detector provides an output signal level indicative of the quality of the signal to which that detector is responsive. A ramp signal is coupled in common to each comparator, and the comparator that first senses a detected output signal level equal to the ramp signal level causes the corresponding received signal to be gated to the output of the system.