Accession Number : ADD003817

Title :   Hybrid Tracking Loop for Detecting Phase Shift Keyed Signals.

Descriptive Note : Patent,


Personal Author(s) : Lindstrum,Alan L

Report Date : 28 Sep 1976

Pagination or Media Count : 11

Abstract : A hybrid tracking loop detector system that accurately demodulates phase shift keyed acoustic telemetry signals. The system internally determines the received carrier frequency and detects phase shifts that denote the digital format depicted by the phase shift keyed signals. The system is particularly useful for operating at low signal to noise ratios and with relatively short messages. The detector includes a phase lock loop comprising a phase comparator, an amplifier, an adjustable filter and a voltage controlled oscillator. The phase and frequency of the oscillator are divided and are locked to the carrier frequency of the received signal and are used as a reference for the phase comparison detection. The system has two sequented modes of operation, a direct acquisition mode and a holding mode. The detector switches automatically from the direct acquisition mode to the holding mode.

Descriptors :   *Patents, *Phase detectors, *Phase shift keyers, Hybrid circuits, Demodulation, Acoustic signals, Telemeter systems, Phase locked systems

Subject Categories : Electrical and Electronic Equipment

Distribution Statement : APPROVED FOR PUBLIC RELEASE