Frequency-shift-keyed receiver

Details Frequency-shift-keyed receiver Frequency-shift-keyed receiver

1977-09-06

1979-05-22

Martin, John C.

Demodulators

Amplitude modulation demodulator

Having specific distortion, noise or other interference...

329122, 340310A, 340171A, 340207R, 361 67, 178 66A, H04B 116, H04L 2714, H04M 1100, G08C 1914

Patent

active

041561945

ABSTRACT:
Frequency-shift-keyed signals are detected by a receiver having an input which supplies the received signals to first and second mixers. A local oscillator produces signals at a frequency midway between the two frequencies of the frequency-shift-keyed signals. The oscillator signals are supplied to the first mixer at a first phase angle (sine), and are supplied to the second mixer at a second phase angle (cosine) displaced 90 degrees with respect to the first phase angle. The first mixer output is applied to a first lowpass filter which removes the high frequency (or sum) signals and passes only the low frequency (or difference) signals. The second mixer output is applied to a second lowpass filter which also removes the high frequency (or sum) signals and passes the low frequency (or difference) signals. The first filter signals are applied to a first 90 degree phase shifter, and the second filter signals are applied to a second 90 degrees phase shifter. First sum and difference circuits are connected to the two filters and the two phase shifters to produce two signals, each of which varies between two levels depending upon which frequency is received. Second sum and difference circuits are connected to the two filters and the two phase shifters to produce two signals, each of which also varies between two levels depending upon which frequency signal is received. Each of the signals produced by the two sum and difference circuits can be rectified and summed to produce an output signal which also varies between two levels depending upon which frequency signal is received. This output signal provides reliable indication of the frequency of the received signals, and can be used in various ways, such as in guard-trip control of power systems.

REFERENCES:
patent: 3568067 (1971-03-01), Williford
patent: 3854099 (1974-12-01), Kratt et al.
patent: 3971988 (1976-07-01), Denenberg
patent: 4013965 (1977-03-01), Scharte
patent: 4015206 (1977-03-01), Huntley
Park, "An FM Detector for Low S/N," IEEE Trans. on Communication Technology, vol. Com-18, No. 2, Apr. 1970,pp. 110-118.
Denenberg, "Spectral Moment Estimators," Bell System Technical Journal, vol. 55, Feb. 1976, No. 2, pp. 143-155.

Affiliated with

Also associated with

Rating

Frequency-shift-keyed receiver does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Frequency-shift-keyed receiver, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Frequency-shift-keyed receiver will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1042989