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:
Feb. 20, 1996
Filed:
Aug. 03, 1992
Yasuaki Takahara, Yokohama, JP;
Shigeyuki Sudo, Fujisawa, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
A communication system which includes a receiving section having a frequency convertor for converting a received signal into an intermediate frequency signal by mixing with a local oscillation signal, and a demodulator for demodulating the received signal converted into the intermediate frequency signal, a transmission section for modulating a transmission signal received thereby, to transmit the so modulated signal, and an input/output section for receiving the demodulated signal from the receiving section and outputting it externally and receiving the transmission signal externally and outputting it to the transmission section. The receiving section includes a local oscillator for generating the local oscillation signal, reference frequency generator for generating a reference signal, calibration signal generator for generating a calibration signal having a predetermined frequency based upon the reference signal, to input the calibration signal to the frequency converter, counter for counting the frequency of the intermediate frequency signal, and corrector for detecting a frequency error based upon the counted value of the intermediate frequency signal. The frequency converter converts the calibration signal into the intermediate frequency signal by mixing with the local oscillation frequency. The counter counts the frequency of the calibration signal converted by the frequency converter as the intermediate frequency signal. The corrector detects the frequency error from a frequency difference between the counted value of the calibration signal and a predetermined intermediate frequency reference value, thereby generating a signal for frequency correction based upon the thus detected frequency error.