Pulse or digital communications – Receivers – Automatic frequency control
Patent
1996-02-21
1998-02-03
Chin, Stephen
Pulse or digital communications
Receivers
Automatic frequency control
375373, 455209, H04L 2706
Patent
active
057152810
ABSTRACT:
A zero intermediate frequency radio receiver that comprises mixing stages, an A to D converter, a digital demodulator, a carrier tracking system and a carrier nulling system is disclosed. The mixing stages receive FM or PM signals and produce analogue in-phase and quadrature baseband signal which are in turn converted to digital baseband signals by the A to D convertor. DC offsets in the baseband signals are removed by high pass filtering prior to demodulation. Tracking enables the baseband signals to be maintained at a centre frequency of substantially zero hertz, while signal strength at this frequency is minimized or mulled before the DC offset filtering. Information which might otherwise be removed by the filtering is thereby retained in the baseband signals, which are relatively less distorted.
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Bly, deceased Stephen
Lane Mark Vernon
Siddall William Mark
Chin Stephen
Ghayour Mohammad
Tait Electronics Limited
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