Abstract: A vehicle detector capable of detecting motorized vehicles, bicycles only or both types of vehicle in a loop near a controlled intersection. The vehicle detector includes a processor under control of machine readable code for controlling the operation of one or more oscillators coupled to one or more loops. Manually actuatable switches enable the entry of mode settings—i.e., motorized vehicle and bicycle detect or bicycle only detect—and clearance time parameters for ensuring that one or more bicycles can safely proceed through an intersection when given a green light. Selection of the Bicycle detect mode is denoted by the entry of a non-zero value in an initial timer using one or more of the switches.

Abstract: A vehicle detector capable of detecting motorized vehicles, bicycles only or both types of vehicle in a loop near a controlled intersection. The vehicle detector includes a processor under control of machine readable code for controlling the operation of one or more oscillators coupled to one or more loops. Manually actuatable switches enable the entry of mode settings—i.e., motorized vehicle and bicycle detect or bicycle only detect—and clearance time parameters for ensuring that one or more bicycles can safely proceed through an intersection when given a green light. Selection of the Bicycle detect mode is denoted by the entry of a non-zero value in an initial timer using one or more of the switches.

Abstract: An automatic vehicle identification (AVI) system signal processing technique which provides improved performance and reliability and which substantially eliminates the adverse effect of ambient noise signals on the detection of permissible code sequences by an AVI receiver. Input signals to an AVI receiver are filtered to strip off all frequency components except those at the carrier frequency. The filtered signals are subjected to variable gain amplification over a substantially linear operating range with the maximum amplitude of the amplified signals limited to a maximum value below the supply voltage and within the linear range of the variable gain amplifier. The amplified signals are converted to a binary pulse train signifying the temporal length of each active carrier period and the temporal length of each quiescent carrier period. The binary pulse train is decoded and a valid vehicle signal is generated if the decoded binary pulse train matches a permissible code sequence.

Abstract: The field of the present invention is parking meters and more particularly to the use of electronically operated parking meters coupled with a sensor for positively sensing unobtrusively the presence or absence of a vehicle in a specified parking space controlled by the sensor and electronically operated parking meter. An induction coil mounted below the surface of the parking area is used to provide positive signals to the electronically operated parking meter and a cpu upon both the entrance of a vehicle into the parking space and the movement of the vehicle from the parking space. Moreover, the detecting system is battery operated and the battery life is extended by duty cycle operation of the detector system, whereby only a small portion of a detecting cycle is actually employed for detecting the status of the parking space.

Abstract: A method and apparatus for visually and audibly verifying Call signal generation in a vehicle detector. A generated Call signal drives a visible display, such as a discrete LED, an LED display composed of multiple discrete LEDs, or an LCD display. The same generated Call signal also controls the operation of an audible tone generator so that an audible tone is generated whenever the vehicle detector generates a Call signal.

Abstract: A programmable vehicle detector with operator actuatable function selection and parameter value setting keys, and an operational display. A small cluster (four) of key switches enables an operator to select programmable vehicle detector functions, such as pulse/presence, scanning/non-scanning, end of green control; and also adjust the value of settable parameters, such as loop frequency, sensitivity, delay time, and maximum presence time. The value of certain parameters is displayed, either by manual interrogation by operation of the switches during a set mode or automatically during normal operation. During normal operation, the display also indicates dynamically the relative value of the loop inductance, using a unique bar graph, the generation of Call a signal, and the time remaining in a delay time period and a maximum presence time period. The display further indicates which of several channels has been selected for function and parameter programming, or is currently being monitored for operation.

Abstract: A vehicle detector with improved reference tracking routines in both the Call direction and the No Call direction. Call direction tracking includes rate sensitive tracking in which the reference is only changed in response to small fluctuations in loop frequency due to drift, and one or more fixed decrementing tracking intervals during which the reference is decremented at a fixed rate for a maximum predetermined period of time. Call direction tracking also includes infinite tracking during which the reference is decremented to an end value representative of loop inductance prior to the generation of a call signal. No Call tracking permits reference updating only after the loop frequency has stabilized for a minimum period of time, a minimum number of loop frequency samples or both.