SU725037A1 - Arrangement for measuring periodic signal - Google Patents

Description

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 The invention relates to the pulsation and measuring technique, and is intended for measuring periodic signals with a fluctuating period against the background of noises.

The known device containing the generator, adder, analog-to-digital Converter (ADC), the driver and the display unit.

The disadvantage of these devices is low measurement accuracy.

The closest to the technical essence of the present invention is a device comprising a first block of tracking the signal period, a time interval meter, a sampling time generator, an ADC. adder, measuring unit and random access memory unit.

The disadvantage of the device is low measurement accuracy.

The purpose of the invention is to improve measurement accuracy.

This goal is achieved by the fact that, in the device containing the first block of tracking the signal period sequentially connected, the time interval meter, the driver

sampling points, ADC, adder and measurement unit, as well as an operational storage unit, the input of which is connected to the second output of the adder, and the output is connected to the second input of the adder; inputting a serially connected delay unit, and a second tracking unit for the signal period, the output of which is connected to the second input of the Bbi6opOK torque generator, while the input of the delay unit is connected to the input of the first monitoring unit for the signal period, and the output of the delaying unit .

FIG. I is an electrical diagram of a device for measuring a periodic signal; in fig. 2 - graphs of voltages explaining the principle of its operation.

Claims (2)

The device contains a block I delay, ADC 2, adder 3, unit 4 measurement, operational storage unit 5, the first unit 6 for tracking the signal period, meter 7 time intervals, shaper 8 instants of samples, the second unit 9 for tracking the signal period. 3 7 The device operates as follows. The measured periodic signal Ug (t) is fed to the inputs of block 1 and block 6, which at the beginning of each period produce a short pulse arriving at the input of the meter 7 time intervals. Denote the duration of the current signal period, during which the discrete values of the signal si Ail are measured, by T, and the duration of the previous device’s known period, through T, the starting points of the A / D converter 2 in the second signal period (see Fig. 2 a) are :. , Т, Зйп .-, п where i is the current number of the signal sample; n is the number of samples per period signal. The number of samples in each period at any frequency of the signal is constant and equal to n, i.e. harmonics from the first to y of the signal are investigated. Let the maximum value of the fluctuations of the adjacent signal periods be ± b Jf K-1 rnQH1-J-, 1ДТ ", oh I - - - - .. (I) to The accuracy of determining the starting times of the ADC 2 according to (1) Dynamic error measurement of a periodic signal. u ,. u;, w / 4an .; .. i.e. depends on the derivative of the signal at the moments of launch and the value of 5 ,. To eliminate the dynamic error, it is necessary that the starting points of the A / D converter 2 be 3Qn.i n i 1. 2, ..., n, (3) 5 O and Di "O, In this case, in the proposed device, the signal The A / D converter 2 enters via delay unit 1, where it is delayed. for a time longer than the maximum value of the digsha period (see. Fig. 2 b). At the same time, the signal goes to block 6, the output of which is connected to the input of the meter 7 time intervals. At time t, the value of the period of the signal T. enters the buffer cascade of the driver 8 instances of 1 samples. At time t, block 9 generates a short pulse arriving at the second input of the imaging unit 8 instants of samples that begins to generate the triggering pulses of the A / D converter 2, the distance between which is equal to -Ar. (4) These signals are input to the triggering input of the A / D converter 2, which processes signal, shift time T relative to the input. Thus, at the moment of time tj, the (K-1) -and signal period begins to be processed, with the measured value Tj, which eliminates the dynamic measurement error. When the period of the signal changes, the moments of occurrence of the ADC trigger gates also change. 2. After each measurement cycle equal to one signal period, the accumulated signal for the previous periods is recorded in block 5. With a new measurement cycle, the signal amplitude values coming from the A / D converter 2 and corresponding; phase angles ((/ | -. 2tg), add up with the values stored in block 5 and corresponding angles tf .. The number of averaging points for the signal period is chosen according to the Kotelnikov theorem. T T 2f where the excimal frequency of the periodic signal spectrum. The number is averaged Since the signal is coherent, the signal power P in the accumulation process increases in proportion to N, and the power of incoherent schum Pp in proportion to N, so the power ratio after accumulation increases. ln e N. Pp N After N accumulation of periods, information from the output of the adder 3 is fed to the input of block 4. Formula of Invention Device For Measuring a Periodic Signal Containing the First Period Tracking Unit, Periodizer, Sample Shaper, Analog-to-Digital a converter, an adder and a measuring unit, as well as an operational storage unit, the input of which is connected to the second output of the adder, and the OUTPUT is connected to the second input of the adder, characterized in that to increase measurement accuracy, a serially connected delay block and a second block for tracking the signal period, the output of which is connected to the second input of the sampling moment generator, are inserted into it, while the input of the delay block is connected to the input of the first block for tracking the signal period, and the latency of the delay block is connected to the input of the analog-digital converter.