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Fault Detection

Spread-spectrum-receiving-apparatus

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Spread spectrum receiving apparatus

Details

Inventors: Kitade, Takashi; Miya, Kazuyuki;
Assignee: Matsushita Electric Industrial Co., Ltd. (Osaka, JP)
Primary Examiner: Chin; Stephen
Assistant Examiner: Liu; Shuwang
Attorney, Agent or Firm: Lowe Hauptman Gopstein Gilman & Berner

A receiving apparatus is disclosed which comprises: a receiving circuit for receiving a radio wave signal including a pilot signal and data signal respectively spectrum-spread and converting the received radio wave signal in a base band signal; a Doppler frequency prediction portion for predicting a Doppler frequency due to a fading; a correlation detector including pilot signal PN code generation circuit for detecting a correlation between the pilot signal in the base band signal and a pilot signal PN code from the pilot signal PN code generation circuit every data length of the pilot signal; a correlation length changing portion for outputting a portion of the detected correlation with a length of the portion of the detected correlation varied in accordance with the Doppler frequency from the Doppler frequency prediction portion; and a demodulator for demodulating the base band signal to detect and output the data signal with a distortion of the data signal due to the fading compensated in accordance with the portion of the detected correlation. The length of the portion of the detected correlation is varied by a switch circuit or a weighting circuit.

DETAILED DESCRIPTION The aim of the present invention is to provide an improved spread spectrum receiving apparatus.
According to the present invention, a first receiving apparatus is provided, which comprises: a receiving circuit for receiving a radio wave signal including a pilot signal and a data signal respectively spectrum-spread and converting the received radio wave signal into a base band signal; a Doppler frequency prediction portion for predicting a Doppler frequency due to a fading; a correlation detector for detecting a correlation with respect to the pilot signal in the base band signal every data length of the pilot signal; a correlation length changing portion for outputting a portion of the detected correlation with a length of the portion of the detected correlation varied in accordance with the Doppler frequency from the Doppler frequency prediction portion; and a demodulator for demodulating the base band signal to detect and output the data signal with a distortion of the data signal due to the fading compensated in accordance with the portion of the detected correlation.
According to the present invention, a second receiving apparatus is provided which comprises: a receiving circuit including an antenna for receiving a radio wave signal including a pilot signal and data signal respectively spectrum-spread and converting the received radio wave signal into a base band signal; a Doppler frequency prediction portion for predicting a Doppler frequency due to a fading from the base band signal; a correlation detection portion for detecting a correlation with respect to the pilot signal in the base band signal every data length of the pilot signal; a filter circuit for filtering the detected correlation by weighting the detected correlation in accordance with the Doppler frequency from the Doppler frequency prediction portion; and a demodulator for demodulating the base band signal to detect and output the data signal with a distortion of the data signal due to the fading compensated in accordance with the weighted correlation

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