Telecommunications – Receiver or analog modulated signal frequency converter – Frequency or phase modulation
Patent
1987-11-18
1988-12-20
Griffin, Robert L.
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency or phase modulation
455214, 455243, 455245, H04B 116, H04B 110
Patent
active
047929910
ABSTRACT:
The present invention minimizes noise pops due to Rayleigh fades by controlling receiver gain relative to the average received signal strength so that only a predetermined level of limiting occurs prior to the recovery of the audio information. The amount of limiting is selected so that a significant Rayleigh fade will cause the amplified IF signal to drop below the limiting level and enter the linear amplification region. During the fade the magnitude of the signal provided to the discriminator decreases thereby decreasing the discriminator's output and minimizing the magnitude of the audio pop. Additional minimization of the subject noise pops is achieved by utilizing a discriminator which has a square law transfer characteristic so that the recovered audio level will decrease 2 dB for every 1 dB decrease in input signal level.
REFERENCES:
patent: 3036211 (1962-05-01), Broadhead
patent: 3832638 (1974-08-01), Ohashi et al.
patent: 3982186 (1976-09-01), Furuno
patent: 4013964 (1977-03-01), Skutta
patent: 4123711 (1978-10-01), Chow
patent: 4313215 (1982-01-01), Jansen
patent: 4379207 (1983-04-01), Kubota
patent: 4393354 (1983-07-01), McGinn
patent: 4403348 (1983-09-01), Leland et al.
patent: 4450590 (1984-05-01), Lafferty
patent: 4466129 (1984-08-01), Skutta
patent: 4580286 (1986-04-01), Richards, Jr.
patent: 4648126 (1987-03-01), Toffolo
patent: 4648127 (1987-03-01), Jongepier
Signetics Analog Applications Manual, 1979, pp. 225-232.
"Performance of a Two Branch Post-Detection Combining UHF Mobile Radio Space Diversity Receiver", thesis by Anthony J. Rustako, Jr., 1969, pp. 26-29, 38-40, 43-50, 53-58.
"FM Noise with Fading Channels and Diversity", by Bruce R. Davis, IEEE Transactions on Communication Technology, vol. Com-19, No. 6, Dec. 1971, pp. 1189-1200.
"An FM Detector for Low S/N", by John H. Park, Jr., IEEE Transactions on Communication Technology, vol. Com-18, No. 2, pp. 110-111, Apr. 1970.
Angle Modulation: The Theory of System Assessment, by J. H. Roberts, 1977, pp. 204-213.
"Simplified Baseband Diversity Combiner", by R. T. Adams, IRE Transactions on Communications Systems, Dec. 1960.
"Multiplication by Square of Envelope as Means of Improving Detection Below FM Threshold", by J. H. Roberts, IEEE Transactions on Communication Technology, Jun. 1971, pp. 349-353.
"Variants of Conventional FM Demodulation Having the Aim of Improving Poor Signal-To-Noise Ratios", by John H. Roberts, Proceedings of Radio Receivers and Associated Systems, IEE Conference, Jul. 1972.
"Voice and Digital Transmission in a Mobile Radio Channel at 850 MHz (A Tutorial Presentation)", by G. A. Arredondo and J. I. Smith, NEC Proceedings, 1974, pp. 74-79.
"Reduction of Threshold Noise in FM Receivers Operating in Quasisynchronous Field", by M. O. Al-Nuaimi, B.Sc., Ph.D., C. Eng., MIEE, IEE Proceedings, vol. 132, Pt. F, No. 2, Apr. 1985.
David Middleton, "On Theoretical Signal-to-Noise Ratios in FM Receivers: A Comparison with Amplitude Modulation", Journal of Applied Physics.
Copies of Selected Portions of the Manual for General Electric's Cellular Personal Radio MT-391FOR6A.
Heinz Ammon et al., "High Performance FM-IF IC for Systems with Search Tuning Stop and Multipath Interference Detection", IEEE Transactions on Consumer Electronics (Aug. 1986), Section 2.3.
Griffin Robert L.
Motorola Inc.
Smith Ralph E.
Warren Charles L.
LandOfFree
FM receiver having improved audio quality in response to Rayleig does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with FM receiver having improved audio quality in response to Rayleig, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and FM receiver having improved audio quality in response to Rayleig will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1914082