Communications: electrical – Vehicle detectors – Environmental or drift compensation
Patent
1983-09-14
1985-01-01
Swann, III, Glen R.
Communications: electrical
Vehicle detectors
Environmental or drift compensation
246249, 340551, 340941, G08G 100
Patent
active
044918410
ABSTRACT:
A vehicle detector has an inductive sensing loop that is a frequency determining element of an oscillator. A first counter is operated to sample the oscillator frequency or period and the count achieved is applied as a preset reference to a second down counter which is counted down in one sample period while a fresh count value is being established in the first counter. The residue in the second counter at the end of a sample period is examined by detection logic to determine the presence of a vehicle. Preferably the first counter is updated every Nth sample period whereas the second counter is activated every sample period. Upon vehicle detection the first counter is frozen at the value preceding detection, the second counter continuing operation. During vehicle detection third and fourth counters are operated in the manner of the first and second counters respectively before detection, detection logic examining the residues in the fourth, down, counter to generate control signals for incrementally adding or subtracting from the count values in the first and third counters so as to reflect ambient changes during vehicle presence. In order to detect the departure of the vehicle, the second counter is consequently preset with the predetect value of the first counter as adjusted for ambient change.
REFERENCES:
patent: 4296401 (1981-10-01), Duley
Sarasota Automation Limited
Swann III Glen R.
LandOfFree
Self-adjusting inductive object-presence detector does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Self-adjusting inductive object-presence detector, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Self-adjusting inductive object-presence detector will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-579489