Fault detecting circuit and method for a vehicle detector system
US4566008A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 29, 1982 |
| Grant date | Jan 21, 1986 |
| Priority date | — |
| Expiry date | Jun 29, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG08G1/042
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
Apparatus and method for a circuit which is connected in series between the call signal output of a vehicle detector and the call signal input of a traffic controller is disclosed. Under normal operating conditions the invention acts as a signal buffer and input of the invention will be applied to the input of the traffic controller when call signal inputs are continuously present or not present for preestablished times, then test procedures are implemented. During a test or failure condition of the vehicle detector, the detector output signal will be disconnected from the controller. The invention also provides a circuit which is connected between the loop and the loop input of the vehicle detector. The circuit along with the accompanying method is designed to modify the input impedance to the vehicle detector to apply a test or "forced" call signal to the vehicle detector input when a call signal input is not received after a predetermined period of time, a fault condition is established. Indicators display the operating states of the call signal output to the controller and/or the fault mode of the vehicle detector in the event of a fault condition. Apparatus is available for pr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.