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. 25, 1986
Filed:
Jun. 24, 1983
Robert Boudault, Limours, FR;
Abstract
An FSK modem transmission circuit which includes a modulator adapted to sctably produce pairs of low and high frequency carrier waves in any combination of up to five frequencies specified in international and U.S. standards. The modulator circuit includes a regenerative feedback loop which generates a triangular carrier wave at a frequency determined by the resistance of a resistor network having five different settings selected by switches therein controlled by the data signal and by logic control signals. The transmission circuit also includes a filter which modifies the waveform of the transmitted carrier wave to suppress odd harmonics thereof, thereby isolating the carrier wave from the modem receiver circuit which is coupled to the transmission circuit by a hybrid coupler.