SU1652923A2 - Method of forming signal amplitudes difference taken at two time interval - Google Patents

Abstract

This invention relates to a measurement technique. The purpose of the invention is to improve accuracy. The device implementing the method contains 1.2 delay lines 1.2, an attenuator 3, a limiting amplifier 4 multipliers 5.6, low-pass filters 7.8.12, a subtracting block 9, a voltage divider 10, a quadrant 11. With their help from a limited in amplitude and delayed signal form a signal with information about the parasitic amplitude modulation of the main delayed signal, which is eliminated in the device. 1 il.

Description

ON SL Yu Yu

yu so

Yu

where S (t) is the amplitude; (o is the frequency; p (t) is the signal phase; and n is the harmonic number.

ten

The amplitude-limited signal is attenuated in amplitude, i.e. convert to signal

oo, K So 2) - sin nwt + ny (t),

n 1,3,5 ....

The invention relates to a measurement technique, can be used in measuring fluctuations of the amplitude of a signal, and relates to the improvement of a known method according to the author. USSR № 834543.

The purpose of the invention is to improve the accuracy of forming the difference of the amplitudes of the signals counted at two points in time. The drawing shows a generalized block diagram of a device implementing the method. The method is as follows. Signal to be investigated

U (t) S (t) + p (t) is limited in amplitude, i.e. 15 where k is the attenuation coefficient; into a signal with a constant amplitude of S0 - the amplitude of the limit.

° 1 The amplitude-attenuated signal of uSo 2 is sin n yt + n y; (t), the signal to be studied is U (t), and the products of multiplication are 20

°° 1 KS0 2 -jf) unfp (t) S (t) + y (t)

n 1,3.5 ....

 Kj & {S (t) / 2-S (t) cos 2at + 2p (t) / 2 + S (t) (t) x x 2 -J-slntnftM np (t) j,

n 1.3.5, ...

P n 1,3.5 ....

where S (t) is the amplitude; (o is the frequency; p (t) is the signal phase; and n is the harmonic number.

The amplitude-limited signal is attenuated in amplitude, i.e. convert to signal

oo, K So 2) - sin nwt + ny (t),

n 1,3,5 ....

where k is the attenuation coefficient; S0 is the limiting amplitude.

filter and get the signal KS0S (t) / 2.

Delay in time for the interval g of the investigated and limited amplitude signals. At the same time, in the delayed amplitude-limited signal K S0 (Ko + D K (t)) (tr) + p (tr) - and the delayed test signal (Ko + D K (t)) S (t - g) sin C1 - d) + p (t - d) n is the parasitic amplitude modulus K of SolKo + D K (t)) sin - t) + tft - t) (Ko + D K (t)) S (t - d) sin - d) + p (t - f KSn (Ko + Dk (1)) 25 (1-g) (tr) + p (tr) - kS (Ko + DK (t for S (t -g) {- cos 2 -t) + 2 p (i -t) / 2,

dependent on the parasitic amplitude modulation, i

From a limited delayed signal (Ko Ch - D K (t)) So K sin w (1 - t) + / 5 (t - g) form a fluctuating signal

S% K2 (K0 -t-AK (t) 2)

2

carrying information about spurious amplitude modulation, for example, using quadratic amplitude detection.

The generated signal So K (K0 + + D K (t)) / 2 controls the amplitude of KSo (K0 + + D K (t)) 2 S (t - t) / 2 delayed filter

chi, the magnitude and behavior of which is determined by the factor DK (t). It is caused by the fundamental impossibility of the ideal time delay operation, the dependence of the attenuation of the delayed signals in amplitude on the frequency of the signals, and a wide range of frequencies of the delayed signals.

The delayed signals multiply and receive the signal

For example, by dividing the signals, as a result, the signal S (t-r) / KS0 is obtained.

The difference between the filtered KSoS (t) / 2 and 5 (g-t) / K50 signals is determined, and the delayed signal filtering product is 5 (1-t) / K5o. The weight of K2S02 / 2 is grafted, and the resulting difference is obtained (t) -S (tr) amplitudes of signals counted at two points in time.

 The block diagram of the device that implements the method contains the first and second i lines 1 and 2 of the delay, the inputs of which are connected to the input and - through a step attenuator 3 - the output of the amplifier-limiting device

4 and the inputs of the first multiplier 5, and the outputs of the first and second lines 1 and 2 of the delay are connected to the inputs of the second multiplier 6, the first and second filters 7 and 8 of the lower frequencies connected to the outputs of the respective multipliers, subtracting unit 9 connected between the outputs of the filter 7 and voltage divider 10, one of the inputs connected in series with filter 8, the output of subtractive unit 9 connected to the output terminal of the entire device, and the input terminal of the device connected to the input of the amplifier-limiter 4, quad 11, whose input is Connected to the output of the second line 2 delay, and the output - through the low-pass filter 1 - to the second input of the divider 10.

The device works as follows.

The studied signal U (t) S (t) sin s t + + f (t) with f (amplitudes of S (t) and phase (/) (t) are limited in the amplifier-limits, i.e. convert to a signal with a constant amplitude of So, and in a step attenuator 3, the amplitude is attenuated by K - 2V / S0 times, where V is any positive integer. The output signal of the attenuator is oo

Ua (t) K% 2 -J-sln n ot np (t),

n 1,3,5 ,. .

Ue (t) (Ko + AK (t)) S (t - g) sin w (t - g) + p (. - t) x (K -, f AK (t)) So K sin - t) + p (t - T) SoK x

x (Ko + A K (t)) 2 {S (i - r / 2 - S (t - r) cos 2 -T) + 2tfi-r) / 2}

Multiplier 5 output

oo, Us (t) U2 (t) U (t) S (t) () -KS0 C -jj-sln nwt «-ny (t)

n - 1.3.5,

 K SojS (t) / 2 - Sy cos 2 a) t - f 2 p (t) + S (t) sin w t - f p (t) x

00

to 2 (t) I

n 5.3,5 ...

filter in the low pass filter 7, and then receive a signal

U (t) KSoS (t) / 2.

The output signal of delay line 2 is squared. The result of the quadration of U1 i ((t) U2 (t) {Ko + A K (t)) 2 {11I- (t-z) + 2 (t-r) / 2} K2S0 is filtered in a low-pass filter 12.

8 low pass filter output

Us (t) SoK (Ko + AK (t)) 2 S (t - g) / 2

0

five

0

five

0

in multiplier 5, multiply by the signal U (t) under study and, in addition, with their help 2 delays are performed with the signal U (t) delayed by time g in line 1 of the delay. Since the signal under study and the output signal of the attenuator 3 contain a wide range of frequencies, the real amplitude-frequency characteristics of the delay lines 1 and 2 are inherently uneven, i.e. if their transmission coefficient in frequency has a constant component MQ (o) and a variable component K0, then the signal under study, after passing through delay line 1, is converted to

Ui (t)

(Ko + A K (t)) S (t - d) sin eo (t - d) + p (t - t),

I

where D K (t) determines the magnitude and behavior of the parasitic amplitude modulation resulting from the non-uniformity of the amplitude-frequency characteristic of the delay line. The output of attenuator 3 in delay line 2 is converted to U2 (t)

(Ko + A K (t)) So K sin w (t - r) + p (- r) The output signals of lines 1 and 2 of the delay in multiplier 6 are multiplied one by one, resulting in a signal

divided in divider 10 by 12 low-pass filter output

U 12 (t) K2S02 (Ko + D K (t)) 2 /; then receive the signal

Uio (t) S (t-z) / KSo.

Subtraction unit 9 performs the conversion

U9 (t) U7 (t) -Uio (t) K2So2 / 2, as a result of which we have UGZ-3 - which is the sought difference in the amplitudes of the signals measured at two points in time and is not dependent on the parasitic amplitude modulation arising from - due to the non-uniformity of the amplitude-frequency characteristics of the delay lines.

Thus, the proposed method makes it possible to increase the accuracy of generating the difference in amplitudes of signals measured at two points in time, by reducing the error due to the non-ideal performance of the time delay of the test and the limited amplitude of the signals.

Claims (1)

The invention of the method of forming the difference of the amplitudes of the signals counted in two points 0 five time, by auth. USSR Ms 834543, characterized in that. that, in order to increase the accuracy of forming the amplitude difference of the signals counted at two points in time, parasitic fluctuating components of the amplitudes of the delayed and delayed amplitude-limited input signals are extracted, they are generated and modulated amplitudes of the delayed and delayed amplitude-limited input signals.