CDMA synchronous acquisition circuit
First Claim
1. A CDMA synchronous acquisition circuit for receiving a CDMA signal to synchronously acquiring the CDMA signal, comprising:
- a receiving unit for decoding a reception base band signal which is spread-modulated in a CDMA mode;
a correlation circuit for calculating a correlation value for the received base band signal every timing within one chip of a spread code by a correlator; and
means for detecting the maximum value of the correlation value to estimate the spread code generation timing of a spread-modulated transmission base band signal within a precision of one chip of the spread code,wherein said correlator includes offset removing means for removing a DC offset component due to unbalance of the code balance of the spread code.
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Abstract
A CDMA synchronous acquisition circuit for receiving a CDMA signal and performing synchronous acquisition on the CDMA signal, comprises a receiving unit for receiving a signal and decoding the received signal to a reception base band signal which is spread-modulated in a CDMA mode, a correlation circuit for calculating a correlation value for the received base band signal every timing within one chip of a spread code by a correlator, and means for detecting the maximum value of the correlation value to estimate the spread code generation timing of a spread-modulated transmission base band signal within a precision of one chip of the spread code, wherein the correlator includes offset removing means for removing a DC offset component due to unbalance of the code balance of the spread code.
58 Citations
14 Claims
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1. A CDMA synchronous acquisition circuit for receiving a CDMA signal to synchronously acquiring the CDMA signal, comprising:
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a receiving unit for decoding a reception base band signal which is spread-modulated in a CDMA mode; a correlation circuit for calculating a correlation value for the received base band signal every timing within one chip of a spread code by a correlator; and means for detecting the maximum value of the correlation value to estimate the spread code generation timing of a spread-modulated transmission base band signal within a precision of one chip of the spread code, wherein said correlator includes offset removing means for removing a DC offset component due to unbalance of the code balance of the spread code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A CDMA type receiver comprising:
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a quasi-coherent detecting circuit for receiving a transmission signal which is spread-modulated in a CDMA mode to decode a base band signal; an A/D converter for converting the base band signal to digital data; a correlator for calculating a correlation value between the digital signal of said A/D converter and the spread code; synchronous acquisition circuit for detecting the maximum value of the correlation value to perform matching processing between the spread code timing of the spread-modulated transmission base band signal and the spread code; and a spread code generating circuit for generating the spread code, wherein said correlator includes offset removing means for removing a DC offset component due to unbalance of code balance of a spread code applied thereto, said spread code generating circuit includes a phase shift circuit, and said synchronous acquisition circuit outputs the maximum correlation value of said correlator.
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12. A method of synchronously acquiring a received CDMA signal, comprising:
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converting the received CDMA signal to a base-band signal; converting the base-band signal to a digital base-band signal; correlating the digital base-band signal using a first spread code for the CDMA signal to provide a first correlated signal; and removing D.C. offset components from the first correlated signal by adjusting the first correlated signal by a value corresponding to imbalance in symbols of the CDMA signal. - View Dependent Claims (13, 14)
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Specification