Accession Number : ADD015329

Title :   Adaptive Filter Technique for Suppression of Wideband or Offset Narrowband Radio Frequency Interference.

Descriptive Note : Patent, Filed 21 Dec 90, patented 17 Mar 92,

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Miller, Jeffry J

Report Date : 17 Mar 1992

Pagination or Media Count : 8

Abstract : The adaptive filter for frequency modulation of the present invention utilizes an audio tone multiplexed into the baseband modulation spectrum as a pilot tone to control and determine the amount of adaptation of the effective and variable bandwidth of the filter for optimum selectivity and rejection of wideband interference or narrowband offset interference. The multiplexed tone is detected and the filter is adjusted according to the signal-to-noise ratio of the detected tone. A continuous and adaptive decrease or increase in bandwidth is produced to accommodate the actual signal bandwidth to achieve rejection of interference with minimum distortion. Additionally, the filter compensates for transmitter drift of center frequency. This filter may be used at radio or intermediate frequencies.

Descriptors :   *ADAPTIVE FILTERS, *FREQUENCY MODULATION, *PATENTS, AUDIO TONES, BANDWIDTH, CONTROL, INTERFERENCE, INVENTIONS, NARROWBAND, PILOTS, RATIOS, REJECTION, SIGNAL TO NOISE RATIO, VARIABLES, NOISE(RADIO), RADIO SIGNALS

Subject Categories : Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE