Detector Systems, Inc.

Indicator Controls Corporation

Thomas R Potter

Thomas W Seabury

A method and system for transferring information between a moving vehicle and a stationary information location having a vehicle detector system with a loop antenna by using the loop antenna as either the receiving antenna for signals transmitted from a moving vehicle or as the transmitting antenna for signals generated by a transmitter located at the vehicle detector site for transfer to a receiver mounted on a moving vehicle. The information is encoded on a carrier having a frequency outside the normal frequency range of the vehicle detector system, preferably by interrupted carrier pattern processing.

Vehicle communication system using existing roadway loops wherein the

Vehicle communication system using existing roadway loops

A method of updating the reference count in a period shift measurement vehicle detector permits conditional reference count updating in the No Call direction whenever the sample count minus reference count difference value lies between the upper limit of a jitter/vibration guard and band and a positive freeze reference threshold. Decrementing of the reference count is permitted in the call direction whenever the sample count minus reference count lies in a range from 0 to a negative freeze reference threshold. Variable hysteresis for call/no call signal generation is provided in a single vehicle detector, with the call direction threshold selectable between two values.

Vehicle detector method and system

The pedestrian traffic control system of this invention utilizes an endless belt to successively display visible painted WALK, DONT START, and DONT WALK signs in a window of a display unit. The control unit may be employed with an ordinary three-state power system of the type that now operates flashing neon signs, but has the advantage that electric power operates the signs only when a sign is being moved into display position. Three distinct WALK, DONT START, and DONT WALK signs are used thereby avoiding the ambiguity of present systems in which a flashing DONT WALK sign cautions the pedestrian not to start, but to continue on his way. The movement of the endless belt is controlled by detecting markers, such as perforations, on the endless belt, thus assuring proper registration of the signs in display position. Electrical energy that becomes stored while the sign is energized drives the sign to display the DONT WALK sign, if the power fails. The invention may be applied to other types of endless signs and with other types of control means that move synchronously with the endless sign.

Pedestrian traffic control system

A monitoring system is provided for use in conjunction with a wire loop which is embedded in a roadway, and which senses the presence of vehicles in the roadway to control a traffic signal. The monitoring system senses the output of the loop oscillator which is included in the traffic control circuitry and which generates a loop signal and whose frequency-determining circuit includes the wire loop to indicate immediately any failure in the loop circuit. If for any reason the loop oscillator fails to operate, that fact will be sensed immediately by the monitoring system of the invention, and such a failure will be equated to a failure in the embedded loop, or in the lead-in circuit which connects the loop to the loop oscillator. A digital embodiment of the monitoring system of the invention includes a reference oscillator which generates a reference signal whose frequency is lower than the frequency of the loop signal, and it also includes a two-count binary counter which is clocked by the reference signal, and which is cleared by the loop signal so that the counter cannot exceed a count of one, so long as the loop oscillator is functioning. However, should the loop oscillator fail, indicating a failure condition in the loop, the counter will then proceed to the count of two, and that count will set a flip-flop to activate an appropriate indicator. The flip-flop will remain set and the indicator activated, until reset by appropriate manual means. An analog embodiment of the monitoring system of the invention is also provided.

Traffic signal loop monitoring system

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.

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Los Alamitos, CA, United States of America

Thomas R Potter