Traffic control system and method of operation
Number of patents in Portfolio can not be more than 2000
United States of America Patent
Stats
-
Mar 9, 1999
Grant Date -
N/A
app pub date -
Dec 18, 1997
filing date -
Dec 18, 1997
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A vehicle detector comprising a flux gate magnetometer with vertical and horizontal sensing coils is positioned within a roadway. The ambient levels of the earth's magnetic field as sensed by the magnetometer are used to establish reference levels and deviations therefrom are evaluated by a microprocessor which produces a vehicle arrived signal when the vertical component of sensed perturbations exceed a threshold and in an alternate mode when either vertical or horizontal levels exceed threshold values. Both vertical and horizontal levels must fall below threshold levels to determine a departure in either mode. Vehicle arrival and departure events are encoded as NRZ data packets which are transmitted by an edge-fired antenna as FM modulated signals. A remote multi-channel receiver capable of responding to a plurality of magnetometer modulated FM transmitters processes the received data and provides signals that are used by traffic signal controlling computers.
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