U.S. patents available from 1976 to present.
U.S. patent applications available from 2005 to present.

Direct conversion FM receiver

Patent 5003621 Issued on March 26, 1991. Estimated Expiration Date: Icon_subject November 2, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Patent References

Synchronous radio or television receiver with analog high frequency section followed by digital low frequency section
Patent #: 4464770
Issued on: 08/07/1984
Inventor: Maurer ,   et al.

Carrier reproducing circuit for phase shift keying signals
Patent #: 4639682
Issued on: 01/27/1987
Inventor: Takeuchi

Dual conversion FM receiver using phase locked direct conversion IF
Patent #: 4653117
Issued on: 03/24/1987
Inventor: Heck

Baseband demodulator for FM and/or AM signals
Patent #: 4677690
Issued on: 06/30/1987
Inventor: Reed

Digital zero IF selectivity section
Patent #: 4733403
Issued on: 03/22/1988
Inventor: Simone

Digital FM demodulator using delayed signal product with arctangent
Patent #: 4750214
Issued on: 06/07/1988
Inventor: Hart ,   et al.

Method of, and demodulator for, digitally demodulating an SSB signal
Patent #: 4803700
Issued on: 02/07/1989
Inventor: Dewey ,   et al.

Method of receiving frequency-modulated stereo multiplex signals
Patent #: 4817167
Issued on: 03/28/1989
Inventor: Gassmann

Dual port FM demodulation in phase locked receivers
Patent #: 4837853
Issued on: 06/06/1989
Inventor: Heck

Nearly DC IF phase locked transceiver
Patent #: 4852123
Issued on: 07/25/1989
Inventor: Bickley ,   et al.

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Inventor

Assignee

Application

No. 430467 filed on 11/02/1989

US Classes:

455/209, Plural local oscillators or mixers455/316, With frequency stabilization for at least one local oscillator455/324Homodyne (i.e., zero beat or synchrodyne reception)

Examiners

Primary: Eisenzopf, Reinhard J.
Assistant: Charouel, Lisa

Attorney, Agent or Firm

International Class

H04B 001/30

Abstract

A direct conversion FM receiver that comprises a quadrature mixer, an A to D converter, a digital demodulator, a digital phase lock loop, and frequency offset setting means is disclosed. The quadrature mixer receives FM signals and mixes them with a local oscillator signal to produce an analog in-phase baseband signal and an analog quadrature baseband signal. The analog in-phase baseband signal and the analog quadrature baseband signal are converted into digital signals by the A to D converter. The digitally converted baseband and quadrature signals are digitally demodulated and filtered by the digital demodulator such that modulation information is produced. The modulation information is used, at least in part, to control the phase lock loop means. In addition, the phase lock loop is offset by the frequency offsetting means such that the desensing components of the analog devices are minimized, thus, substantially reducing the need for tight component tolerance of DC sensing components and the need for manufacturing adjustments of DC desensing components.

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