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:
Mar. 02, 1976
Filed:
Sep. 03, 1974
Thomas R Potter, Los Alamitos, CA (US);
Indicator Controls Corporation, Gardena, CA (US);
Abstract
A high resolution digital test instrument is provided which has particular, although not exclusive, utility in testing the inductance and inductance changes of wire loops which are embedded in roadways and which are incorporated into vehicle presence sensing systems. The test instrument provides a simple means for determining the sensitivity of the loop to vehicles of different sizes; as well as for determining whether the loop inductance is susceptible to drift, whether open circuit or short circuit conditions exist, whether there are intermittent circuit breaks, and a variety of other conditions. The instrument includes frequency counting circuitry which counts, on a selected time basis, the output frequency of a Class C oscillator. The frequency of the oscillator is determined by the combined loop and lead-in inductance together with the lead capacitance of the loop circuit being tested. The pulses generated by the oscillator are cyclically counted over a selected time period, and the results are displayed as a frequency measurement.