Fault detecting circuit and method for a vehicle detector system

A vehicle detector monitor having input and output terminals thereof comprising:

• means for receiving a call in signal at a said input terminal when a vehicle is detected,
• means for initiating a control timer when a call in signal become present at said input terminal, said control timer having a predetermined timing period such that a first control signal is produced while said call in remains present at said input terminal during said timing period and a second latching control signal is produced when said call in signal remains present at said input terminal in excess of said timing period,
• means operably coupled said input and output terminals for passing said call in signal to said output terminal in response to said first control signal and disconnecting said call in signal from said output terminal in response to said second latching control signal, and
• means for generating a synthetic c ll in signal for input to said output terminal in response to said second control signal wherein said synthetic call in signal is a one of a constant signal level and a pulsed signal of predetermined pulse duration and frequency.

A vehicle detector monitor having input, output and control terminals comprising:

• means for receiving a call in signal at said input terminal said call in signal resulting from detection of a vehicle,
• means for initiating a first control timer when said call in signal is no longer present at said input terminal, said first control timer having a first predetermined timing period such that a first control signal is produced while said call in signal remains not present at said input terminal during said first predetermined timing period, and a second control signal is produced when said call in signal is continuously not present at said input terminal in excess of said first predetermined timing period,
• means for operably coupling said input and output terminals in response to said first control signal,
• means for introducing a sensor simulator at said control terminal and initiating a second control timer in response to said second signal, said sensor simulator providing an activation of a call in signal without detection of a vehicle, said second control timer having a second predetermined timing period such that said first timer will be automatically reinitiated when said call in signal becomes present during said second predetermined timing period and a latching control signal is produced when said call in signal remains not present at said input terminal in excess of said second predetermined timing period, and
• means for operably disconnecting said input and output terminals in response to said latching control signal.

A method for coupling a vehicle detector output to a traffic controller input comprising the steps of:

• receiving a call in signal from said vehicle detector output when a vehicle is detected,
• generating a call out signal in response to said call in signal,
• comparing said call in and call out signals,
• developing a first control signal when said call in and call out signals correspond and a second control signal when said call in and call out signals do not correspond,
• coupling said call out signal to said traffic controller input in response to said first control signal, and
• disconnecting said call out signal from said traffic controller input in response to said second control signal.

A method for a vehicle detector monitor having input and output terminals thereof comprising the steps of:

• receiving a call in signal at said input terminal when vehicle is detected by a vehicle detector;
• initiating operation of a control timer when a call in signal becomes present at said input terminal, said control timer having a predetermined timing period,
• producing a first control signal while said call in signal remains present at said input terminal during said timing period and a second latching control signal when said call in signal remains present at said input terminal in excess of said timing period,
• passing said call in signal to said output terminal in response to said first control signal, and
• disconnecting said call in signal from said output terminal in response to said second latching control signal.

A method for a vehicle detector monitor having input and output terminals thereof comprising the steps of

• receiving a call in signal at said input terminal, said call in signal generated when a vehicle is detected,
• initiating a control timer when a call in signal becomes present at said input terminal, said control timer having a predetermined timing period,
• producing a first control signal while said call in signal remains present at said input terminal during said timing period and a second latching control signal when said call in signal remains present at said input terminal in excess of said timing period,
• passing said call in signal to said output terminal in response to said first control signal,
• disconnecting said call in signal from said output terminal in response to said second latching control signal, and generating a synthetic call in signal for input to said output terminal in response to said latching control signal.

A method for a vehicle detector monitor having input, output and control terminals comprising the steps of:

• receiving a call in signal at said input terminal, said call in signal indicating detection of a vehicle;
• initiating a first control timer when said call in signal is no longer present at said input terminal, said first control timer having a first predetermined timing period,
• producing a first control signal while said call in signal remains not present at said input terminal during said first predetermined timing period and a second control signal when said call in signal is continuously not present at said input terminal in excess of said first predetermined timing period,
• operably coupling said input and output terminals in response to said first control signal,
• introducing a sensor simulator at said control terminal and initiating a second control timer in response to said second control signal, said sensor simulator activating a call in signal without detection of a vehicle, said second control timer having a second predetermined timing period,
• automatically reinitiating said first timer when said call in signal becomes present during said second predetermined timing period and producing a latching control signal when said call in signal remains not present at said input terminal in excess of said second predetermined timing period, and operably disconnecting said input and output terminals in response to said latching control signal.

A method for coupling a vehicle detector monitor output to a traffic controller input comprising the steps of:

• receiving a signal by said vehicle detector monitor from vehicle detector output when said vehicle detector detects a vehicle and generating a signal by said vehicle detector monitor in response to said receiving signal;
• comparing said received and generated signals;
• generating a control signal by said vehicle detector monitor in response to said comparing step;
• and
• selectively coupling or decoupling said vehicle detector output to said traffic controller in response to said control signal.