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:
Aug. 25, 1998
Filed:
Apr. 25, 1997
Kenji Nowara, Okegawa, JP;
Juichi Nakada, Kumagaya, JP;
Advantest Corporation, Tokyo, JP;
Abstract
The signal to be measured is converted into digital form and read into a memory 13 using a trigger as the reference, and a signal of a length 1/5 that of the signal to be measured, in the vicinity of the trigger, is orthogonal-transformed (14). A frequency error .omega..sub.1 of the transformed output I.sub.1,Q.sub.1 is estimated (15) and is used to correct the output I.sub.I, Q.sub.I (16). The corrected output I.sub.2,Q.sub.2 is subjected to processing by a receiving filter (17), and the filtered output I.sub.3,Q.sub.3 is synchronized with a PN code to obtain an ideal signal R.sub.I,R.sub.Q and a phase difference .tau..sub.1 is calculated. The signal I.sub.3,Q.sub.3 and the ideal signal R.sub.I,R.sub.Q are used to obtain a frequency error .omega..sub.2 and a phase error .tau..sub.2 of the signal I.sub.3,Q.sub.3. All signals to be measured, stored in the memory 13, are subjected to orthogonal transformation (23) so that the frequency error .omega..sub.1 +.omega..sub.2 and the phase error .tau..sub.1 +.tau..sub.2 are removed, and the transformed output I.sub.5,Q.sub.5 and the signal R.sub.I,R.sub.Q are used to calculate modulation parameters as is the case with the prior art.