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1. (WO1991008624) METHOD AND APPARATUS FOR RANDOM FM NOISE CANCELLATION
Latest bibliographic data on file with the International Bureau

Pub. No.: WO/1991/008624 International Application No.: PCT/US1990/006784
Publication Date: 13.06.1991 International Filing Date: 26.11.1990
Chapter 2 Demand Filed: 30.05.1991
IPC:
H03G 3/28 (2006.01) ,H03G 3/32 (2006.01) ,H04B 1/12 (2006.01)
H ELECTRICITY
03
BASIC ELECTRONIC CIRCUITRY
G
CONTROL OF AMPLIFICATION
3
Gain control in amplifiers or frequency changers
20
Automatic control
22
in amplifiers having discharge tubes
26
Muting amplifier when no signal is present
28
in frequency-modulation receivers
H ELECTRICITY
03
BASIC ELECTRONIC CIRCUITRY
G
CONTROL OF AMPLIFICATION
3
Gain control in amplifiers or frequency changers
20
Automatic control
30
in amplifiers having semiconductor devices
32
the control being dependent upon ambient noise level or sound level
H ELECTRICITY
04
ELECTRIC COMMUNICATION TECHNIQUE
B
TRANSMISSION
1
Details of transmission systems, not covered by a single one of groups H04B3/-H04B13/123; Details of transmission systems not characterised by the medium used for transmission
06
Receivers
10
Means associated with receiver for limiting or suppressing noise or interference
12
Neutralising, balancing, or compensation arrangements
Applicants:
MOTOROLA, INC. [US/US]; 1303 East Algonquin Road Schaumburg, IL 60196, US
Inventors:
BIRCHLER, Mark, Allen; US
JASPER, Steven, Charles; US
Agent:
PARMELEE, Steven, G. ; Motorola, Inc. Intellectual Property Dept. 1303 East Algonquin Road Schaumburg, IL 60196, US
Priority Data:
443,99830.11.1989US
Title (EN) METHOD AND APPARATUS FOR RANDOM FM NOISE CANCELLATION
(FR) PROCEDE ET APPAREIL D'ANNULATION ALEATOIRE DE BRUIT DE MODULATION DE FREQUENCE
Abstract:
(EN) A method for reducing noise caused by fading in FM radio systems . The algorithm described operates on a sequence of complex samples received at the input of the discriminator (501) from the output of the IF filter of a digitally implemented radio. After determination of magnitude (502), which yields the raw envelope of the received signal, the raw envelope information is processed via parallel paths to determine characteristics indicative of shape, amplitude and time of occurrence of noise pulses. The output signal from the discriminator (501) is processed (508) to determine noise pulse direction. A pulse generator (510) produces counter pulses based upon the previously determined characteristcs, and the counter pulses are combined (513) with the discriminator output to substantially cancel the noise pulses.
(FR) Procédé de réduction du bruit provoqué par l'évanouissement dans des systèmes radio à modulation de fréquence. L'algorythme décrit fonctionne sur une séquence d'échantillons complexes reçus à l'entrée du discriminateur (501), provenant de la sortie du filtre FI d'une radio à commande numérique. Après détermination de l'intensité (502), laquelle produit l'enveloppe brute du signal reçu, les informations d'enveloppe brute sont traitées par l'intermédiaire de chemins parallèles, afin de déterminer des caractéristiques indiquant la forme, l'intensité et le temps d'apparition d'impulsions de bruit. Le signal de sortie provenant du discriminateur (501) est traité (508) afin de déterminer le sens des impulsions de bruit. Un générateur d'impulsions (510) produit des contre-impulsions basées sur les caractéristiques préalablement déterminées, et les contre-impulsions sont combinées (513) à la sortie du discriminateur, afin d'annuler les impulsions de bruit.
Designated States: AU, BR, CA, JP, KR
European Patent Office (AT, BE, CH, DE, DK, ES, FR, GB, GR, IT, LU, NL, SE)
Publication Language: English (EN)
Filing Language: English (EN)
Also published as:
EP0506708KR1019920704467AU1991068931