GB1026101A - Measuring vehicle speeds - Google Patents

Abstract

1,026,101. Electric selective signalling systems. L. ROHDE and H. SCHWARZ, [trading as ROHDE AND SCHWARZ]. April 18, 1963 [April 19, 1962], No. 15255/63. Heading G4H. [Also in Division G1] The speed of a vehicle over a predetermined distance is measured by recording constant frequency pulses on a track driven at a speed proportional to the vehicle speed, subsequently driving the track at a constant speed in playback apparatus, measuring the intervals between successive pairs of pulses, and continuously displaying the results of repeated measurements. Fig. 9 shows part of the playback apparatus, in which a timer TG supplies pulses through an AND-gate UZ to a counter ZK. Pulses J from the pick-up head trigger a monostable multivibrator M3 to close the AND-gate for a time t3. Simultaneously evaluation device AE (digital printer or curve recorder) is put into operation to record the number in counter ZK. When M3 reverts to its initial state the counter is reset and gate UZ is opened. The measured value differs from the interval between a pair of pulses J by t3, a known constant. Instead of resetting counter ZK to zero it may be reset to a number corresponding to the time t3 so that the numerical result is directly equivalent to the pulse spacing. In a modification AND-gate UZ and multivibrator M3 are omitted. When a pulse J arrives the value stored in ZK is transferred to AE and ZK is simultaneously reset. Arrangements are also described in which a capacitor is charged at a constant rate during a pulse-interval and the charge at the end of the interval is measured (see Division G1).