GB1449677A - Digital velocity meter - Google Patents

Abstract

1449677 Velocity measurement; duration and frequency measurement PLESSEY CO Ltd 30 May 1974 [21 June 1973] 29484/73 Heading H3H Apparatus giving a direct measurement of velocity from the period of passage between two points comprises a clock oscillator, two serially connected variable divides between the clock oscillator and a counter, each divide dividing the clock frequency by a factor equal to the counter contents and a device for displaying the counter content at the end of the period. The dividers produce a hyperbolic variation of clock frequency. Preferably the counter counts up from zero until full at the clock rate and then down with the hyperbolic varying clock rate. As shown, a start signal at the beginning of the period enables gate CG to pass clock signals from source MO via fixed divider SD to counter U/D.C. When the counter is full CG operats to enably the variable dividers RM1, RM2 and to pass the clock pulses directly thereto. The p output pulses from RM2 pass via SD to the counter which now counts down and the division factor is continually varied in accordance with the counter readings. At the stop signal, CG removes the enabling signal from the dividers and the counter reading is displayed on device DD. The variable dividers comprise a series of bistable devices forming a counter and a plurality of gats enabled by the binary, parallel counter output. The fixed divider SD removes gitter introduced by the variable dividers. The circuits may also be used to measure frequency.