Pulse or digital communications – Receivers – Interference or noise reduction
Patent
1997-01-27
1999-07-20
Bocure, Tesfaldet
Pulse or digital communications
Receivers
Interference or noise reduction
375350, H04B 110, H03D 104
Patent
active
059265132
ABSTRACT:
A radio receiver for receiving radio frequency (RF) signals includes an analog down-converting and filtering section for down-converting and selecting the RF signals to an intermediate passband and a stopband which substantially determine the widest bandwidth of operation of the radio receiver. An analog-to-digital converter converts the intermediate frequency signal to a sampled digital signal. A digital filtering section, responsive to the sampled digital signal, includes wideband and narrowband digital filters for providing wide bandwidth and narrow bandwidth baseband quadrature output signals for the widest bandwidth of operation and a narrow bandwidth of operation at a frequency within a passband. The wideband digital filtering is designed to only provide a modest amount of additional stopband attenuation with a significantly sharper transition band rolloff from passband to stopband. When this limited digital filtering is applied to the signal that has already been subjected to the analog filtering, the selectivity of the overall receiver frequency response is improved. The receiver may be used for multi-bandwidth operation by simply adding digital filtering to define any narrower passband of interest. This allows bandwidth switching to take place without any changes to the analog circuitry. Simultaneous processing of both wide and narrow modes of operation may be done in the digital signal processor (DSP) performing the digital filtering.
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Suominen Edwin A.
Voboril Charles J.
Alcatel Alsthom Compagnie Generale d'Electricite
Bocure Tesfaldet
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