GB678324A - Improvements in or relating to telemetering systems - Google Patents

Abstract

678,324. Telemetering. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. March 6, 1951. [March 14, 1950] No. 6295/50. Class 40 (i). In a telemetering system wherein impulses are transmitted at a rate proportional to the measured quantity, a capacitor is charged to a predetermined voltage on the receipt of each impulse and thereafter discharges through a resistor until receipt of the succeeding impulse when the capacitor is momentarily connected to a much smaller capacitor, the potential of which is displayed and indicates the quantity. Should the first capacitor be discharged to a potential lower than that of the small capacitor, the latter is rapidly discharged to the potential of the first capacitor. As shown, each impulse over line 70, 11, operates a relay A which operates a delayed release relay B. At the end of each line impulse, A releases to de-energize B which holds however for its delay period. During this time a condenser C1 is fully charged over contacts a2, b1, a resistor R3 from the H.T. supply leads 12, 13. When B releases C1 commences to discharge through resistor R2 and a non-linear resistor NLR of the silicon carbide type, the potential across C1 during discharge being substantially inversely proportional to the time of discharge. When relay A operates on receipt of the next line impulse, the remaining charge on C1 is applied over a2 to a much smaller capacitor C2 which thus assumes the potential of C1. The potential of C2 is measured by a valve voltmeter M calibrated in terms of the quantity being measured. When capacitor Cl is again fully charged upon release of relay A, the meter reading remains due to the charge held by C2. Subsequent line impulses are effective in the same way to apply the remaining charge on C1 to C2 so that the meter reading varies according to the time interval between successive impulses, i.e. to their frequency. If the impulse frequency falls so that C1 discharges to a potential below that of C2 the charge on C2 leaks away by way of diode V2, R2, NLR. Hence, if the line impulses cease, C2 discharges completely to reduce the meter reading to zero. A contact device in the meter may actuate an alarm under such conditions. The relays A, B may be replaced by electronic switches.