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. 20, 1988
Filed:
Nov. 15, 1985
Joseph P McGeehan, Corsham, GB;
Andrew Bateman, Bath, GB;
National Research Development Corporation, London, GB;
Abstract
In those transparent tone-in-band systems which employ a single oscillator in the transmitter to generate a frequency notch between upper and lower portions of a band which is to be transmitted, there is not complete freedom to choose the width of the notch. In the present invention which also uses a single transmitter oscillator, one portion of the band transmitted is selected using a filter. A mixer is used to change the frequency of the input band in a way which does not allow the lower sideband to 'fold' back at zero frequency and interfere with the lower transmitted portion. A further filter selects the other portion for transmission from the output of the mixer.