Television – Image signal processing circuitry specific to television – Noise or undesired signal reduction
Patent
1993-10-08
1994-06-28
Groody, James J.
Television
Image signal processing circuitry specific to television
Noise or undesired signal reduction
375103, 36472417, 36472419, 455307, 348711, 348469, H04N 521, H04N 700, H04N 544, H04N 1100
Patent
active
053252047
ABSTRACT:
A digital notch filter apparatus for removing narrowband interference signals from a wideband communication signal. The apparatus includes a recursive digital passband interference acquisition filter, an acquisition mode center frequency control circuit, a recursive digital passband interference tracking filter, a tracking mode center frequency control circuit and an interference detection circuit. The tracking filter has a narrower bandwidth than the acquisition filter. Both the acquisition and tracking filters are gang tuned so that the center frequencies of their passbands are adjusted in unison. During interference acquisition mode, the acquisition mode center frequency control circuit is used is to adjust the center frequency of the filters over the bandwidth covered by the interference canceler. When the interference detection circuit detects an interference signal within the passband of the tracking filter, the tracking center frequency control circuit is used to adjust the center frequency of the acquisition and tracking filters to insure that the filters remain locked onto the narrowband interference signal. Upon detection of the interference signal, the portion of the communication signal which includes the narrowband interference signal that is passed through the narrow passband tracking filter is subtracted from the communication signal to remove the narrowband interference signal. When no interference signal is detected, the communication signal is permitted to pass to the output of the notch filter circuit without attenuation.
REFERENCES:
patent: 3744015 (1973-07-01), Marimon et al.
patent: 3967102 (1976-06-01), McCown
patent: 4117541 (1978-09-01), Ali
patent: 4199660 (1980-04-01), Dill et al.
patent: 4480236 (1984-10-01), Harris
patent: 4549312 (1985-10-01), Michaels et al.
patent: 4589083 (1986-05-01), Le Dinh et al.
patent: 4667225 (1987-05-01), Kanda
patent: 4673982 (1987-06-01), Tam et al.
patent: 4954785 (1990-09-01), Segaram
patent: 5031194 (1991-07-01), Crespo et al.
patent: 5051963 (1991-09-01), Linville, Jr. et al.
patent: 5058139 (1991-10-01), Egler
patent: 5086340 (1992-02-01), Citta et al.
patent: 5087975 (1992-02-01), Citta et al.
patent: 5121203 (1992-06-01), Citta
patent: 5121208 (1992-06-01), Citta et al.
patent: 5132797 (1992-07-01), Citta
patent: 5136386 (1992-08-01), Okada et al.
patent: 5157697 (1992-10-01), Anuari et al.
patent: 5162900 (1992-11-01), Citta
patent: 5222106 (1993-06-01), Satoh et al.
patent: 5235612 (1993-08-01), Stilwell et al.
patent: 5263048 (1993-11-01), Wade
Daltorro, Jon, "The Implementation of Recursive Digital Filters for High-Fidelity Audio", J. Audio Eng. Soc., vol. 36, No. 11, 1988 Nov., pp. 851-877.
E. P. Darbyshire, "Narrowband Interference Identification and Rejection Applied to Baseband Radio Signals", IEE Conference Publication n.325. Published by IEE, Michael Faraday House, Stevenage, Engl., 1990, pp. 217-221.
General Instrument Corporation Videocipher Division, "Digicipher HDTV System Description", Aug. 22, 1991, pp. 31-40, pp. 49-60.
Zenith, AT&T, "Technical Details, Digital Spectrum Compatible", Sep. 23, 1991, pp. 3-4, 51-56, 67-110.
David Sarnoff Research Center, Philips Laboratories, "Advanced Digital Television, System Description", Jan. 20, 1992, pp. v-vii, 69-113.
Advanced Television Research Consortium, "Advanced Digital Television, Prototype Hardware Description", Feb. 12, 1992, pp. 8-10, 45-57.
McMann, R. H., et al., "A Digital Noise Reducer for Encoded NTSC Signals", SMPTE Journal, Mar. 1978, vol. 87, No. 3, pp. 129-133.
Groody James J.
Hitachi America Ltd.
Metjahic Safet
LandOfFree
Narrowband interference cancellation through the use of digital does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Narrowband interference cancellation through the use of digital , we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Narrowband interference cancellation through the use of digital will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2380701