Direct conversion FM receiver

Details Direct conversion FM receiver Direct conversion FM receiver

1989-03-14

1991-09-24

Eisenzopf, Reinhard J.

Telecommunications

Receiver or analog modulated signal frequency converter

Noise or interference elimination

329327, 375 39, 455304, 455309, 455324, H04B 110, H04B 126

Patent

active

050520504

ABSTRACT:
A direct conversion receiver for demodulating an FM signal converted frequency down converts the signal to quadrature related baseband signals (I,Q). These signals are applied by way of respective d.c. blocking capacitors (16, 18) and differentiating circuits (26, 28) to a differential arctan demodulator (20). The action of the differentiating circuits (26, 28) is to remove any d.c. component in the I and Q signals and to perform a frequency shaping which enables the demodulator (20) to recover correctly the modulating information. Measures are disclosed to overcome the effects of 180 degree phase jumps which will occur when the direction of rotation of the phasor reverses and of frequency dependent amplitude scaling introduced into the differentiated signals (I', Q').

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patent: 4878251 (1989-10-01), Richardson
patent: 4955078 (1990-09-01), Chung

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