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:
Apr. 06, 1976
Filed:
Feb. 21, 1975
Blaupunkt-Werke GmbH, Hildesheim, DT;
Abstract
Frequencies which respectively identify a particular transmitter, and a particular program content, and which are in a very low frequency range (from between 20 to 125 kHz can be recognized, and ditigal output control signals derived representative of whether one, or both, or none of these frequencies are present by use of a frequency selection input circuit, controlled by a change-over switch to initially select recognition of the transmitter identification which, if positive, is applied through a storage circuit having a storage time substantially longer than the switch-over rate, to provide an output signal if the selected transmitter is recognized, and hold that output signal during switch-over of the program content identification signal which, if present, will be fed back through a logic circuit to hold the output of the transmitter identification circuit as identified, and if not present, permit continued switch-over of the frequency identification circuit to continue to store transmitter identification signals, if present, but permit these signals to disappear, after the storage time, if the transmitter identification signals also cease. The time delay and storage circuit preferably include operational amplifiers, and the frequency identification circuit includes a phase-locked loop.