The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 17, 2001
Filed:
Jun. 25, 1997
Masao Nagano, Saitama, JP;
Advantest Corporation, Tokyo, JP;
Abstract
A digitized quadrature detected output of a sampling rate R (=16R,, where R,is the symbol rate) from a quadrature detector is subjected to FFT processing and the frequency of the peak power spectrum of the FFT output is detected. Then, a frequency error &OHgr;,between the frequency of the peak power spectrum and a standardized value is calculated and the frequency error &OHgr;,of the detected output is corrected. The corrected output is decimated by a filter to a signal of a sampling rate 4R,, which is input into an estimate part, wherein a clock phase is calculated which minimizes variance of the amplitude of the input sample data and a frequency error &OHgr;,is computed from a deviation of the signal point of the input sample data from a standardized angle value of the signal. The frequency error &OHgr;,of the output from the filter is corrected, then a clock delay of the corrected output is corrected, and the corrected output is converted by decimation to a signal of a sampling rate R,, from which an ideal signal is derived and used to calculate modulation accuracy parameters in the same manner as in the prior art.