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:
Oct. 30, 1984
Filed:
Dec. 07, 1983
Ian A Vance, Newport, GB;
International Standard Electric Corporation, New York, NY (US);
Abstract
A single channel duplex transmitter/receiver utilizing digital frequency shift keying (FSK) signals. An analogue-to-digital converter frequency modulates the output of a local oscillator whose output is coupled via a mixer/combiner/splitter network to an aerial. FSK signals received from the aerial in the receiver are mixed with the local oscillator output in network to provide quadrature signals which are low-pass filtered before being demodulated in a zero IF demodulator to give a digital output. To avoid unwanted sidetone the output of the A/D converter is fed through a delay to a digital network where it is subtracted from the corresponding signals fed back through the demodulator. The digital signals are then fed to a D/A converter.