Telecommunications – Receiver or analog modulated signal frequency converter – Frequency or phase modulation
Patent
1982-01-25
1984-10-09
Bookbinder, Marc E.
Telecommunications
Receiver or analog modulated signal frequency converter
Frequency or phase modulation
329 50, 329124, 375 80, 455209, 455264, 455316, 455324, H04B 126
Patent
active
044765851
ABSTRACT:
A demodulator of the type employed in a "zero-IF" system uses a local oscillator for providing guadrature output signals at the center frequency of an FM signal to be demodulated. The demodulator has first and second mixers for separately mixing the FM signal with the quadrature signals to provide a first and second output signal each in quadrature at the outputs of said mixers. These signals are low pass filtered. The demodulator includes third and fourth mixers with each mixer receiving at an input one of the low pass signals. At another input the mixers receive third and fourth signals. The third and fourth signals are derived from mixing a variable controlled oscillator (VCO) signal with the local oscillator guadrature signals. The outputs of the third and fourth mixers are applied to the inputs of a difference amplifiers, the output of which controls the frequency of the VCO in an automatic frequency control mode (AFC) to cause the output of the difference amplifier to provide demodulated signal.
A switching means operates to alternate the third and fourth signals as applied to the input of the third and fourth means as well as the output as applied to the difference amplifier to cause an additional amplifier coupled to the outputs of the mixers to provide a DC control signal used for automatic gain control.
REFERENCES:
patent: 4348641 (1982-09-01), Scott et al.
Bookbinder Marc E.
International Telephone and Telegraph Corporation
O'Halloran John T.
Ruzek Peter R.
LandOfFree
Baseband demodulator for FM signals does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Baseband demodulator for FM signals, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Baseband demodulator for FM signals will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1605251