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:
Jan. 06, 1998
Filed:
Feb. 14, 1995
Han-chiu Wang, Palo Alto, CA (US);
Eugene Hwan, San Carlos, CA (US);
Yen-fang Chao, Fremont, CA (US);
Digital Microwave Corporation, San Jose, CA (US);
Abstract
A digital frequency shift keying (FSK) transmitter provides direct frequency modulation in a wide bandwidth loop. In one embodiment, a discriminator circuit recovers from the output signal of the transmitter a base band signal, which is then compared with the input base band signal to provide an error signal for controlling the output oscillator circuit. In another embodiment, the output oscillator is controlled by a phase detector detecting the phase difference between the base band modulating signal and the output signal of the transmitter. An additional narrow bandwidth loop can be added to compensate for frequency drift in the output oscillator due to temperature or other environmental changes.