SU1688176A1 - Method of measurement of root-mean-square values of wide-band signals - Google Patents

Abstract

The invention relates to electrical measuring technique. The purpose of the invention is to improve the accuracy and simplify the method. The method consists in dividing the signal into low-frequency and high-frequency components, measuring their square rms and extracting the square root of the total measurement results. The attenuation of signals at low-frequency (LF) and high-frequency (HF) filtering according to the Knc (a)) + (br} 1, where Knc and Kvch are the attenuation coefficient modules, ensures the elimination of errors associated with the imperfection of real filters, and the simplification of the method, because it does not require reconfiguration of filters when measuring signals with different frequency spectrum. 1 Il. E

Description

This invention relates to electrical measuring technique.

The purpose of the invention is to improve the measurement accuracy and simplify the method

The drawing shows the block diagram of the device for implementing the method

The device contains filters 1 and 2 of the lower (LPF) and upper (HPF) frequencies, meters 3 and 4 squares of the root-mean-square value (RMS) of the low-frequency and high-frequency components of the signal, adder 5, and element 6 of extracting the square root. The input of the device through the LPF 1 and the meter 3 is connected to the first input of the adder 5, and through the HPF 2 and the meter 4 to the second input of the adder 5, the output

which through element 6 is connected to the output of the device.

The method is carried out as follows.

The measured voltage U (t) by filters 1 and 2 is divided into a low frequency UFM and a high frequency UHF (1) component. Measuring instruments 3 and 4 carry out the measuring of the squares of their RMS Knc and 11 nch, respectively. After summing the last in adder 5 and extracting the square root in element 6, we obtain a signal U proportional to the RMS of the measured signal U (t). Thus, the following algorithm is implemented in the device

About 00 00

h |

about

and inc + U & -0)

where U is the output signal of the device;

Inch - RMS low frequency component of the signal;

UBH - RMS of the high frequency component of the signal. ..- ,;

Express DHM and UBH through RMS Garm & nickname DI of the measured signal and the modules of the coefficient of transmission of the low-pass filter Knc (o) and-F.VCh1 KvchN

t / j

 Ј U (OJ |)

I 1

00

 Ј U KWH (MI),

where hell is the circular frequency of the signal harmonics. Substituting (2) and (3) into (1), we get

U U Ј (w) + k1ch (m) 1I t 4

M 1

l

Hence, taking into account the fact that Knc (w) + + Kwh (w) 1, we get

0

five

0

five

singing higher harmonics during low-frequency filtering and lower harmonics of high-frequency filtering gri, as well as simplifying its implementation, since it does not require reconfiguration of separating filters when the spectrum of measured signals changes.

Claims (1)

Invention Formula A method for measuring the rms value of wideband signals, which consists in separating the signal into low and high frequency components by means of low-frequency and high-frequency filtering, measures the squares of the root-mean-square values of these components, and extracts the square root of the sum of the obtained measurement results, distinguishing by that, in order to improve measurement accuracy and simplification, low-frequency and high-frequency filtering is performed with signal attenuation according to equality  (co) + KWh I 1. those. the output signal of the device is equal to the RMS of the measured signal. The method provides the elimination of errors associated with incomplete submission where cnc (m) is the modulus of the signal attenuation coefficient for low-pass filtering; KWH (L) is the modulus of the signal attenuation coefficient for high-frequency filtering; o) - circular frequency signal.