Accession Number : AD0667567

Title :   INTERFERENCE REDUCTION TECHNIQUES EMPLOYING ACTIVE DEVICES.

Descriptive Note : Final rept. 1 Dec 66-30 Nov 67,

Corporate Author : GEORGIA INST OF TECH ATLANTA

Personal Author(s) : Denny,Hugh W. ; Byers,Robert A. ; Driskell,Carl R. ; Wilson,Charles S.

Report Date : FEB 1968

Pagination or Media Count : 95

Abstract : This report discusses the development and performance of several techniques employing active devices for the reduction of adjacent and co-channel interference in receivers. For operational situations where the interfering source is co-sited with the receiver, an automatic phase control system is described which detects the differential phase shift between the interference path and the direct path from the source and supplies a phase corrected signal for cancellation of the interfering signal. For the more general situation where the interference is not a cosite source, a feed forward system and a dual loop, phase locked system were developed. The dual loop cancellation system generates an auxiliary signal to cancel the interfering signal. The improved performance of passive preselectors that can be obtained through Q multiplication is demonstrated with a Q multiplier device for the UHF region. Active and passive circuit configurations which incorporate the extremely narrow passbands of quartz crystals are discussed. When used as band stop filters, interference rejection levels greater than 50 dB are possible with these filters. (Author)

Descriptors :   (*RADIO RECEIVERS, RADIO INTERFERENCE), (*RADIO INTERFERENCE, REDUCTION), COMMUNICATION AND RADIO SYSTEMS, PERFORMANCE(ENGINEERING), PHASE LOCKED SYSTEMS, PHASE SHIFT CIRCUITS, ULTRAHIGH FREQUENCY, AMPLITUDE MODULATION, AUTOMATIC, TRANSMITTER RECEIVERS, SUPPRESSORS, QUARTZ RESONATORS, ELECTRIC FILTERS, FEEDBACK AMPLIFIERS, TRANSISTOR AMPLIFIERS, NARROWBAND, SENSITIVITY

Subject Categories : Radio Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE