Abstract: A single-channel-per-carrier multiple-access communication system including a voice-activated transmission power controller operable in the absence of voice signal input to attenuate the transmission power or modulator output signal to a predetermined level under the control of voice detector output, facilitating carrier sync recovery at the receive end and simplifying design and structure of the demodulator.

Abstract: A circuit for extracting a clock signal from a double-binary phase-shift keying system is disclosed. The carrier wave form is regenerated at the receiver from the phase-shift keyed (PSK) signal input. The regenerated carrier wave is frequency doubled and frequency mixed with the PSK input signal which has also been frequency doubled. A desired clock signal is thereafter extracted from the mixed signal by a band-pass filter. The system does not include a frequency divider which would result in a phase ambiguity.

Abstract: A circuit for extracting a carrier wave signal from a double binary PSK signal input is disclosed. The PSK input signal is applied to a first frequency doubler which doubles the frequency of the input signal. The output of the first frequency doubler is applied to a second frequency doubler and to first and second band-pass filter circuits. The second frequency doubler serves to quadruple the frequency of the PSk input signal and derives a signal having a line spectrum at the frequency 4fc whenever there is no phase shift between successive time slots of the PSK signal. The first and second band-pass filters derive first and second signals having line spectra at frequencies 2fc + fs and 2fc - fs, respectively, whenever there is a phase shift of +90.degree. or -90.degree., respectively, between successive time slots of the PSK input signal.

Abstract: An automatic frequency control circuit is disclosed which is capable of noise suppression and sufficiently reducing the frequency deviation or offset of an input signal at an output, regardless of the variation of the burst width of the input burst signal in a time-division multiplex communication system.

Abstract: A carrier wave reproducer device for use in the reception of a multi-phase digital phase-modulated waves for rapidly extracting the carrier wave without the generation of frequencies higher than the carrier frequency is disclosed. In its simplest embodiment, the device employs a delay detector and a cumulative adder circuit to derive a demodulated signal and a modulator for inversely modulating the input multi-phase digital phase-modulated wave with said demodulated signal. The reference carrier wave is then obtained from the output of the modulator. The same principle is used in alternative embodiments used in the reception of a burst form of signal transmitted with a preamble word having a specific pattern.