DE3470617D1 - Circuit arrangement for measuring short time intervals - Google Patents

Abstract

1. A circuit arrangement for measuring time intervals in particular very short time intervals, and for indicating the measured time interval in digital form, being supplied with a start pulse which indicates the start of the time interval to be measured and with a stop pulse which indicates the end of the time interval to be measured, and using a charging arrangement and a counting device which counts oscillator pulses, characterised in that a first delay element (ZG3) is supplied with a start pulse (SE1), that a second delay element (ZG4, ZG5) has a longer delay time than the delay time of the first delay element (ZG3) and supplied with a stop pulse (SE2), that the first delay element (ZG3) is connected to the set input of a bistable trigger circuit (FF) and the second delay element (ZG4, ZG5) is connected to the reset input of the bistable trigger circuit, that the output of the bistable trigger circuit (FF) is connected to an oscillator (OSZ) switched on when the bistable trigger circuit is set and switched off when the bistable trigger circuit is reset, that the charging arrangement consists of a first and a second charging circuit (LD1, LD2) which, during the time interval to be measured, can each alternately be connected to a constant current source (KQ) for a whole period of the oscillator pulse for the generation of a charging voltage proportional to said oscillator pulse, or in the event of the stop pulse for a shortened period, and each be alternately discharged by a discharging circuit (ET1, ET2) in push-pull to the connection to the constant current source, that the outputs of the charging circuits (LD1, LD2) can be connected by a first multiplexer (MX1) with the current potential to an amplifier circuit (VST), that the output of the amplifier circuit (VST) is connected to an analogue-digital converter (AD) switched on by a start signal (ZS6) when the stop pulse (SE2) has occurred so that the only charging voltage (UD) proportional to the duration of the shortened oscillator pulse is converted into a digital value, and that a counting device (FL, FR, NR4, NR5, BZ) is provided, which counts the whole period pulses emitted by the oscillator (OSZ).