GB713347A - Improvements in or relating to apparatus for converting variable quantities into electric pulse code signals - Google Patents

Abstract

713,347. Electric selective signalling. GENERAL ELECTRIC CO., Ltd., and BAYLISS, A. J. Oct. 20, 1952 [Oct. 18, 1951], No. 24356/51. Class 40(1). Apparatus for converting a variable quantity into an electrical pulse code signal comprises a device adapted periodically to count the number of cycles in the output of an oscillator in a time interval and means for pulse coding the numerical count, the oscillator frequency or the duration of the time interval being varied in accordance with the quantity. to be coded so that the numerical count is a measure of the magnitude of the quantity. As shown, a unidirectional voltage representative of a quantity to be telemetered is applied to a potentiometer 2 to control the frequency of an oscillator 3, the output of which is squared at 4, differentiated at 5, and passed through an electronic gate 6 to a binary counter 8 which counts e.g., only the positive output pulses from 5. The gate 6 is opened periodically for a predetermined time by pulses from a pulse timing generator 7. With zero voltage input to the potentiometer 2 the oscillator frequency is such that the counter, which is zeroised between counts is stepped through its maximum value to zero during each gating pulse. Variation of the oscillator frequency will then produce a count corresponding to the potential applied to the potentiometer and hence to the magnitude of the variable. The digits registered in the binary counter are. transmitted sequentially in known manner by a multiplexing device 9 over terminal 10. A plurality of quantities may be transmitted in time multiplex, the voltages representing the several quantities being applied to vary the oscillator frequency in turn. Alternatively, the oscillator frequency may be fixed and the length of the gating pulses varied according to the magnitude of the variable.