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. 11, 1986
Filed:
Feb. 12, 1985
Stuart W Thro, Cary, IL (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
Apparatus for randomly offsetting the frequencies of each transmitter in a simulcast radio communications system is described. The random frequency offsetting apparatus includes a random noise source for generating a noise signal which is amplified and low-pass filtered before application separately or in combination with an information signal to the frequency modulation input of a corresponding transmitter. In frequency modulated systems, the noise signal and information signal are combined and modulated onto the transmitters; whereas, in envelope modulated systems, the noise signal is frequency modulated onto the transmitter, and the information signal is envelope modulated onto the transmitter. Since the frequency of each simulcasting transmitter is randomly varying, deep cancellation nulls created in the overlap areas between transmitters by multi-transmitter interference will be randomly distributed in randomly varying locations. Therefore, communications between a central station and remote stations located in the overlap areas will not be interrupted by the nulls for long periods of time, as was possible in prior art simulcast systems.