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:
Nov. 11, 2003
Filed:
May. 28, 1999
Glen V Rosenbaum, Gilbert, AZ (US);
Other;
Abstract
A complete process is described for demodulating subsidiary communications authorization (SCA) radio signals. This process takes as an input an FM radio signal from a commercial FM telescoping type antenna. The signal is optimally processed through filtering, amplification, and dual detection circuitry to provide a high quality sub-carrier audio signal. Special matching is provided to set the signal's gain, noise figure, and injected distortion levels as a function of the antenna being extended or collapsed. Also, filtering of RF image and IF baseband signals is uniquely and efficiently performed in a radio receiver having an telescoping antenna and audio out line, an SCA radio turner has a matching filter between the antenna and a first FM discriminator to match the level of extension of the antenna, a phase-lock-loop circuit within a second FM discriminator following the first FM discriminator, and sub-carrier audio processing between the FM discriminator and the audio out line. A filter for image rejection is included between the matching filter and the first FM discriminator. The first FM discriminator includes a local oscillator and mixer to convert the incoming RF signal to an IF signal at approximately 10.7 MHz and a square wave detection circuit to convert a main broadcast signal into an audio signal and a sub-carrier signal from a doubly modulated signal to a singly modulated signal.