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:
Dec. 14, 1976
Filed:
Dec. 24, 1975
Harold Garth Nash, Tempe, AZ (US);
Motorola, Inc., Chicago, IL (US);
Abstract
A digital FSK time rate change modulator is responsive to a digital input signal and generates either a first or a second output frequency. The FSK modulator switches from one output frequency to the other in small increments over a predetermined time interval. The FSK modulator includes means for generating a first and a second timing signal and input means for receiving the digital input signal. An up-down counter having an up-count input and a down-count input counts up and down between a first and a second state. First gating means is coupled to the output of the up-down counter and to the input means and passes the second timing signal to the up-count input when a high level digital input signal is present on the input means and the up-down counter is not in the second state. Second gating means is coupled to the output of the up-down counter and to the input means and passes the second timing signal to the down-count input when a low level digital signal is present on the input means and the up-down counter is not in the first state. Variable counter means divides the first timing signal by predetermined number in response to the count on the up-down counter and generates a digital output signal. Sine wave generator means is coupled to the variable counter means and generates a digitally approximated sine wave having the same frequency as the digital output signal from the variable counter means.