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:
Jun. 19, 1984
Filed:
Jul. 23, 1982
Thorn Emi Ferguson Limited, London, GB;
Abstract
In a circuit for indicating reception of stereo signals (for use in e.g. a radio tuner or television) audio signals prevailing in the left (L) and right (R) output channels are applied to respective limiting circuit and the output signals derived are fed to OR gate. When a monoaural signal is detected, the signals in the two output channels will be in coincidence and so the output from the exclusive OR gate remains low. When stereo signals are detected, however, a finite phase difference exists between the two signals and the output for the OR gate is correspondingly high. A Schmitt trigger drives an LED display whenever the output from the OR gate exceeds a preset threshold level to provide an indication that a stereo signal is being reproduced. A capacitor/resistor circuit imposes a time delay on level changes at gate so that the LED display remains illuminated, even during momentary interruptions of the audio signal.