SU703912A1 - Periodic signal measuring device - Google Patents

Description

(54) DEVICE FOR MEASURING A PERIODIC SIGNAL

The invention relates to a pulse and measurement technique and can be used to measure periodic signals with a fluctuating period in the background of noise.

A device for measuring a periodic signal, containing successively connected shaper of short signals, shaper of "Start. and an analog-to-digital converter (ADC), the output of which is connected to one of the inputs of the adder, the output of which is connected to the indicator input, the other input and output of the adder are connected to the Output and the input of the RAM unit, respectively, and the control unit 1. However, the known device has sufficient measurement accuracy.

The purpose of the invention is to improve accuracy.

For this purpose, in the device for measuring a periodic signal containing a series-connected short-wave shaper, a start-up shaper and an analog-to-digital converter (ADC), the output of which is connected to one of the inputs of the adder, the output of which is connected to the input of the indicator, other input and output of the adder connected to the output and input, respectively, of the RAM unit, and the control unit; a threshold element, a matching element, is introduced;

switch and narrowband filter, while the output of the narrowband filter is connected to the input of the shaper of short signals and through the first position of the switch to the other input of the analog-digital

switch, the third output of the adder is connected via a threshold element to one of the inputs of the coincidence element, the other input of which is connected to the output of the Start signal generator, and through the second position of the switch of the threshold element controlled by the signal from the output of the second element is connected to the input of a narrowband filter , the control input of which is connected to the output of the control unit, the input of the latter is connected to the output of the coincidence element.

The drawing shows a structural electrical circuit of the proposed device.

A device for measuring a periodic signal contains an analog-to-digital converter 1, an adder 2, an indicator 3, a RAM block 4, a shaper 5 short signals, a start signal generator 6, a threshold element 7, a coincidence element 8, a control block 9; narrowband filter 10 and switch P. The device operates as follows. To increase the signal-to-noise ratio, a narrow-band filter 10 with adjustable center frequency is applied. The signal from the output of the narrowband filter 10 is fed to the inputs of the ADC 1 and shaper 5, which generates short pulses at the moments of the same extremes of the signal at the output of the narrowband filter 10. Interim pulses equal to the period of the signal at the output of the narrowband filter 10. These Pulses are fed to the shaper 6 which produces each period of the harmonic signal 2p-pulse triggering the ADC 1.

The trigger pulses from the output of the imaging unit 6 are fed to the launch of the A / D converter 1 and to the second input of the coincidence element 8. From the A / D converter output, the measured signal values are fed to the adder 2, which sums the measurement results corresponding to the same trigger points of the A / D converter 1 for the signal period. After each

A measurement cycle equal to one signal period, accumulated over previous periods, the signal values are entered into block 4, with a new measurement cycle of the signal amplitude value, coming from ADC 1 and corresponding to the i-th trigger points,

froraawa ibTca cti value nm w, Schi m use in block 4 and also corresponding to the i-th time of the start of the ADC 1. If the signal accumulated for m periods at the output of adder 2 exceeds the threshold value, then at the output of the threshold element 7

This is the resolving potential, which is fed to the first input of the coincidence element 8 and to the switch 11, as a result of which the narrow-band filter 10 goes into tracking mode for the signal frequency. The magnitude of the threshold value depends on the magnitude of the noise at the output of the narrowband filter 10 and on the number of periods during which the signal is accumulated. Changes in the frequency of the narrowband signal at the output of the narrowband filter 10 are inversely proportional to the bandwidth.

When the useful signal period fluctuates, the interval between the start pulses of the A / D converter 1 also changes, and the values of these intervals go through the input of block 9, from the output of which the control voltage goes to the control input of the narrowband filter iO. When the useful signal period fluctuates, the interval between the trigger pulses also changes, while block 9 changes the center frequency of the narrowband filter 10 in such a way that it tends to become equal to the frequency of the main harmonic of the periodic signal and changes as this frequency changes.

When the period of the signal changes, the moments of appearance of the ADC trigger pulses, but the values of the phase angles of the signal samples do not change, so the adder 2 adds the signal values coming from the ADC 1 at the moments corresponding to the same phase angle of the signal period. This eliminates the nonstationarity of the process due to the fluctuation of the signal period during the measurement.

Claims (1)

Invention Formula A device for measuring a periodic signal containing a series-connected short-wave former, a Trigger signal generator and an analog-to-digital converter, the output of which is connected to one of the inputs of the adder, the output of which is connected to the indicator input, the other input and output of the adder are connected to the output and the input a memory unit, and a control unit, characterized in that, in order to increase accuracy, a threshold element, a coincidence element, a switch and a narrowband signal are introduced In this case, the output of the narrowband filter is connected to the input of the short signal conditioner and through the first position of the switch to another input of the analog-digital converter, the third output of the adder is connected via a threshold element to one of the inputs of the coincidence element, the other INPUT of which is connected to the output of the "Run , and through the second position of the switch controlled by the signal from the output of the threshold element, the second input of the analog-digital switch is connected to the input of the narrow-band filter, l yuschy input of which is connected to the output control unit, coupled to the input of the output of the coincidence element. Sources of information taken into account in the examination 1. Copyright certificate for the application No. 2417022 / 18-09, cl. H 04 L11/08, 1976 (prototype) .., ; 2 th 5 TsUG GCh -: H - - -.