GB1301292A - - Google Patents

Abstract

1301292 Recording measured data INSTEM Ltd 25 Sept 1970 [5 Sept 1969] 44038/69 Heading G4H A system for digitally recording the values of at least two variables such as load and extension in a tensile testing machine or thermal conductivity and time in a gas chromatograph comprises a recording mechanism for providing a digital record of the values of the variables measured at discrete intervals and a circuit for inhibiting the output of data to the recording mechanism except when the measured values of two of the variables differ by a predetermined increment from their previously measured values or, when one of two measured variables is represented by regularly occurring pulses such as time pulses, the measured value of the other variable differs from its previously measured value by a predetermined increment. Analogue signals representing the variables are sampled at discrete intervals by switches 12, 13 and the digital values of the variables are fed to counters 15, 16. As each variable is sampled the previous digital value of each variable is applied via a gate 17 or 18 and a digital-to-analogue converter 19 to respective comparators 20 which also receive the present measured values of the variables. Each comparator has high and low outputs depending on whether the present value is above or below the previous value of the variable and feeds addition or subtraction pulses both to the counters 15, 16 and flp-flops 27, 28. When both flip-flops have been set, gates 32, 33 are opened to permit data in stores 25, 26 to be transferred to the recording mechanism.