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. 07, 1984
Filed:
Jun. 29, 1981
Applicant:
Inventor:
Robert L Bruce, San Diego, CA (US);
Assignee:
Other;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G08G / ;
U.S. Cl.
CPC ...
340941 ; 340933 ; 324236 ; 331 65 ;
Abstract
A circuit used in a traffic control apparatus for detecting changes in the frequency of an oscillator which has an inductive loop-sensor as a resonating element. The circuit comprises a phase-locked loop oscillator with restricted tuning range and a high impedance amplifier followed by threshold detectors adjusted to sense the entry and exit of a vehicle over the area covered by the loop-sensor. The high-resolution of the circuit overcomes long-term drift problems inherent to loop-sensor detectors with analog circuitry.