GB1413082A - Trafficlight control systems - Google Patents

Abstract

1413082 Controlling road traffic signals SOC DE FABRICATION D'INSTRUMENTS DE MESURE 13 Feb 1973 [12 Sept 1972] 7042/73 Heading G4Q A traffic signal installation comprises a vehicle detector unit (2) (Fig. 1, not shown) associated with each set of lights (1), and a controller (3) connected to the detector units and the lights; each detector unit comprising a Doppler radar detector 22 (Fig. 2) and a preamplifier 23 whose output is supplied to the controller (3); the controller comprising, for each input from a detector unit, a variable gain amplifier, e.g. 31, whereby it is possible to adjust the detection range of detector unit at the controller. In the embodiment shown, two inputs 4(A1) and 4(A2) of the controller are each associated with the detector unit associated with respective opposed traffic lanes (A1, A2). The outputs of the variable gain amplifiers 31, 32 are connected to multivibrator circuits 33, 34 respectively, the outputs of the latter being coupled to common OR-gates 35, 36 which supply signals to a circuit 37 which employs counters. The output of circuit 37 passes to a relay coil 38 having an associated contact 39 for actuating the lights. The detection range of the detector units (2) can be varied between one and four lanes by means of the amplifiers 31, 32. The radar detectors 22 may be as disclosed in Specification 1,400,308. In an alternative embodiment (not shown) the outputs of the amplifiers 31, 32 pass to circuits described in Specification 1,400,308.