SU443324A1 - Device for measuring the period of a harmonic signal - Google Patents

Description

Known devices for extracting the period of a harmonic signal are a null organ that determines.

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A disadvantage of the known devices is the low measurement accuracy in the presence of strong broadband additive noise, leading to false zero-level intersections and, consequently, to significant measurement errors.

To improve the measurement accuracy against the background of broadband noise, the proposed device is equipped with two threshold elements, two additional valves, two additional triggers and a pulse shaper, with the inputs of the threshold elements connected to the zero-body input, output

The first threshold element is connected to one of the inputs of the first additional trigger, the second input of which is parallel to the second input of the trigger is connected to the output of the second threshold element, and the output of the first additional trigger is connected through the pulse shaper to the counting input of the second additional trigger and one of the inputs of the 1st an additional valve, the second input of which is connected to the outlet of the zero organ, and the third - to the outlet of the grigger; Whose inputs are connected respectively to the output of the second further flip-flop and the second input of the first additional White, whose output is connected to one input of a pulse counter.

Fig, I shows the block diagram of the device described; Fig 2 - timing charts of his work. The device consists of n: ulorgan I, threshold elements 2 and 5, additional triggers 4.5, trigger. B, valves 7.8, valve 9, counter 10 pulses, generator II reference frequency, and driver 12 pulses. The device works as follows. The input harmonic signal (Fig. 2a), distorted by broadband additive noise, arrives at the null organ I and the threshold elements 2 and 3 with the same threshold levels B in the initial state of the trigger, 5 and b are in zero position. When crossing the signal. Level - Tlo at the moment of time b, the threshold element 5 generates a pulse (fig.26), which throws the triggers 4 and b (fig.2g, e, respectively). In this case, the flip-flop 5 (fig. 2) is also tilted, as the driver 12 emits a pulse when the flip-flop of the flip-flop from the zero to one state. Therefore, the first pulse at the time b, generated by null-organ I when crossing a zero level signal, passes through the open valve 7 to the input of the initial state of the counter 10. The same pulse does not pass through the valve 8 to the input of trigger b, which opens the valve from the moment time 9, which transmits the pulses of the reference generator II to the counting input of the counter 10. At subsequent successive intersections by the zero-level signal, the counter 10 is reset. This happens before the signal crosses the positive threshold, which is UBUN + Uo at time t in Fig .: (p shows the output pulses of threshold element 2) at which trigger 4 returns to the zero state (Fig. 2 g). Therefore, subsequent intersections with a zero-level signal do not cause the meter 10 to drop. When the signal crosses the negative threshold at time LM, element 3 generates a pulse that triggers trigger 4, B the driver 2 triggers this timing (FIG. 2). Therefore, the first next impulse, formed by the zero signal crossing by the signal, passes the valve 8 at the moment of time bs and triggers trigger B (fig. 2 e), due to which this flow is stopped onnyh pulses Ehod meter ID, on phage. 2 shows the dependence of the number of pulses registered by meter 10 on the time during the measurement cycle. nPE / lvlET of the INVENTION A device for measuring the period of a harmonic signal containing a null organ, a reference frequency generator, a trigger, a gate and a pulse counter, characterized in that, in order to improve the measurement accuracy against the background of broadband noise, it is equipped with two threshold elements, two additional gates, two additional triggers and a driver for the pulses, with the inputs of the threshold elements connected to the input of the null organ, the VBGhod of the first threshold element connected to one of the inputs of the first terminal an output trigger, the second input of which is parallel to the second input of the trigger is connected to the output of the second threshold element, and the output of the first additional trigger is connected through a pulse shaper to the counting input of the second additional trigger and to one of the inputs of the 1st additional valve, the second input of which is connected to the output zero -organ, and the third - to the trigger output, the second trigger input is connected to the output of the second additional valve, the inputs of which are connected respectively to the output of the second additional th flip-flop and the second input .First additional gate whose output is connected to one input of a pulse counter.

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443324