Frequency error measuring apparatus and radio apparatus
First Claim
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1. A frequency error measuring method for detecting frequency deviation between a reference clock frequency and a frequency of a receive signal having a prescribed pattern contained therein, comprising the steps of:
- forming a standard pattern for a correlation value detection based on said clock;
correlating the receive signal with the standard pattern so as to detect, for each of a plurality of sequential portions of said receive signal, a complex correlation value CORRk between said standard pattern and the respective sequential portion of said receive signal, where CORRk is associated with a kth sample of said receive signal;
detecting the prescribed pattern by determining a power PREC associated with the receive signal and a power PCORR associated with the correlation value, with said prescribed pattern being detected when a predetermined relationship between PREC, PCORR and a threshold value TH is satisfied; and
computing a frequency deviation between said clock frequency and said receive signal frequency by performing an averaging operation on a sequence of said complex correlation values CORR ;
wherein said predetermined relationship between PREC, PCORR and TH is;
space="preserve" listing-type="equation">P.sub.REC -P.sub.CORR ×
T.sub.H ≦
0.2.
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Accused Products
Abstract
In a radio apparatus of such as digital cellular which transmit and receive audio signals upon coded, the frequency error can be detected easily and certainly even in the environment of high noise level. The frequency error θe is detected according to the detection result of the complex correlation value between the synchronizing signal and the standard signal.
8 Citations
8 Claims
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1. A frequency error measuring method for detecting frequency deviation between a reference clock frequency and a frequency of a receive signal having a prescribed pattern contained therein, comprising the steps of:
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forming a standard pattern for a correlation value detection based on said clock; correlating the receive signal with the standard pattern so as to detect, for each of a plurality of sequential portions of said receive signal, a complex correlation value CORRk between said standard pattern and the respective sequential portion of said receive signal, where CORRk is associated with a kth sample of said receive signal; detecting the prescribed pattern by determining a power PREC associated with the receive signal and a power PCORR associated with the correlation value, with said prescribed pattern being detected when a predetermined relationship between PREC, PCORR and a threshold value TH is satisfied; and computing a frequency deviation between said clock frequency and said receive signal frequency by performing an averaging operation on a sequence of said complex correlation values CORR ; wherein said predetermined relationship between PREC, PCORR and TH is;
space="preserve" listing-type="equation">P.sub.REC -P.sub.CORR ×
T.sub.H ≦
0.2. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for measuring frequency deviation between a reference clock frequency and a frequency of a receive signal having a prescribed pattern contained therein, comprising:
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means for forming a standard pattern for a correlation value detection based on said clock; complex correlation means for correlating the receive signal with the standard pattern so as to detect, for each of a plurality of sequential portions of said receive signal, a complex correlation value CORRk between said standard pattern and the respective sequential portion of said receive signal, where CORRk is associated with a kth sample of said receive signal; detecting means for detecting the prescribed pattern by determining a power PREC associated with the receive signal and a power PCORR associated with the correlation value, with said prescribed pattern being detected when a predetermined relationship between PREC, PCORR and a threshold value TH is satisfied; and means for computing a frequency deviation between said clock frequency and said receive signal frequency by performing an averaging operation on a sequence of said complex correlation values CORRk ; wherein said predetermined relationship between PREC, PCORR and TH is;
space="preserve" listing-type="equation">P.sub.REC -P.sub.CORR ×
T.sub.H ≦
0.7. - View Dependent Claims (7, 8)
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Specification