SU1709247A1 - Device for measuring noise intensity - Google Patents

Description

variable voltage nicknames, two adders, two-input multipliers, and adders per t-inputs.

The disadvantage of this device is due to the low accuracy of determining the parameters of noise, the duration of which is approximately equal to the duration of the signal.

The closest to the proposed technical entity is a spectrum analyzer of noise signals containing a series-connected linear bandpass filter, a detector, an averager and a logarithm block, as well as a delay line with m taps, m subtractors, m multipliers, two adders, a source of adjustable voltage and (t + 1} -th multiplication unit, with each two adjacent taps of the delay line in pairs connected to the corresponding inputs of the subtractors, the first and the last taps of the delay line are connected to the input I will give the last subtraction unit, the outputs of the subtraction units are connected to the corresponding inputs m of multiplication units, the outputs of which are connected to the inputs of the first adder, its output connected to the first input of the (t + 1) -th multiplication unit, the second input of the last connected to the variable-voltage source, and the output (m + 1} of the multiplication unit is connected to one of the inputs of the second adder, the second input of which is connected to the last tap of the delay line ,.

However, the color device is characterized by limited accuracy in measuring the intensity of noise, the spectral and temporal characteristics of which are close to those of useful signals.

The purpose of the invention is to improve the accuracy of the voltage noise intensity by eliminating the influence of voltages of useful signals and narrowband interference on the measurement process.

The goal is achieved by the fact that the spectrum analyzer of noise signals containing a detector, a delay line with m taps, m multiplication units, the outputs of which are connected to the inputs of the first adder, the second adder, are connected in series first and second delay elements, a voltage divider, a subtractor and a module to take the module, the output of which is connected to the first summing input of the second adder, as well as the nonlinear element and the second voltage divider, the detector output through the second voltage divider also with a second input of the subtractor and the first input of the second adder subtractor, whose output is connected via a nonlinear element to the input of delay line taps, each of which is connected to a corresponding input of one of the blocks

multiplying, the second inputs of which are given the same coefficients equal to 1 / t, the output of the device for measuring the intensity of noise interference is the output of the first adder, and

0 input is the input of the detector, the output of which through the first delay element is connected to the second summing input of the second adder, the second subtractive input of which is connected to the output of the first divider voltage 5%.

The introduction of new elements and connections into the spectrum analyzer makes it possible to eliminate the influence of narrowband noise and useful signals on the measurement of the intensity of noise interference, thereby improving the measurement accuracy.

Figure 1 shows a block diagram of a device for measuring the intensity of noise interference; 2 and 3, 5 timing diagrams explaining his work.

An apparatus for measuring noise interference (Fig. 1} includes a detector 1 connected in series, elements 2 and 3

0 delay, the first voltage divider 4, the subtraction unit 5, the module block 6, the second adder 7, the nonlinear element 8 and the delay line 9 with m taps, each of which is connected to the corresponding input of one of the t multiplicators 10. The outputs of the blocks 10 are connected to the inputs of the first adder 11, the output of which is the output of the device. In addition, the output of the detector 1 through the second voltage divider 12 is connected to one of the subtractive inputs of the adder 7, the remaining inputs of which are connected respectively to the outputs of the first delay element 2 and the voltage divider 4. The second input of block 5

A 5 subtract is connected to the output of the second voltage divider 12.

As detector 1, for example, an amplitude detector can be used, as delay elements 2 and 3, and

0 delay lines 9 - typical electrical delay lines. The dividers 4 and 12 of the voltage, as well as all the multipliers combined in block 10, can be implemented as amplifiers with given coefficients.

5 transmissions by voltage (1/2 and 1 / m respectively), for example, by known circuits on operational amplifiers, adders 7 and 11 and block 5 of subtraction can also be implemented on operational amplifiers. A block b module can

be made according to the scheme of full-wave rectifier, for example, on D18 type diodes. A nonlinear element 8 is also implemented on such a diode.

To provide filtering of noise and useful pulse signals against the background of narrowband interference, the delay time in elements 2 and 3 must be equal to the duration of the useful pulse signal (ta Ti). The total delay time in line 9 is chosen equal to the value of 2 gi (t ata 2 gi). This is due to the fact. that with optimal filtering of pulse signals against white noise, the minimum duration of the noise voltage envelope after detector 1 is close to the value of 2 Ge

Consider first the process of filtering a useful video pulse against a narrowband interference.

When the detector receives a mixture of useful pulse signal (C) and narrowband interference (UE) (Fig. 2a), a monopolar video mix of the signal envelope and UE takes place at its output. moreover, the time parameters of the signal differ from the duration of the UE (Fig. 2b). The output voltage of detector 1 in block 12 is reduced in amplitude by a factor of two and fed to the first subtractive input of adder 7 (Fig. 2b). The second input voltage of the detector is applied to the second summing input of this adder 1. delayed in element 2 by the duration of the useful pulse signal T (fig.2g) and on the second subtractive input - voltage Og (fig.2b), delayed in elements 2 and 3 for the time ta 2Gi and also reduced in amplitude twice in voltage divider 4 (fig.2d) At the same time, the inputs from the subtraction unit 5 receive signals from the outputs de 12 and 4. As a result of the interaction in the block 5, the voltages from (fig, 2b) and us (fig. 2d) at its output there are opposite polarity voltages of the cn - front and rear edges, as well as time shifted useful pulses. signals. After conversion in block b, the output signals of subtractor 5 become unipolar (Fig. 2e) and are fed to the first summing input of the adder 7. As a result of the interaction in the adder 7, the voltages Ua-Ue (Fig. 2c-e) at the output of the last are unipolar pulses that are UE residues and are useful pulse signal (2g). Thus, by processing the output voltages of the detector 1, using blocks 2–7 and 12, unipolar pulse signals, comparable in duration with the value of 2Tii, are obtained at the output of adder 7. at the same time, the voltage of the UE is almost eliminated. Upon arrival at the input of the detector 1

the high-frequency mixture of the useful pulse signal, narrowband interference and noise (Fig. 2h), the output voltage of the detector 1 has, for example, a view. shown on the plot of Ug {fig.2i). After processing video Ug

in blocks 2-7 and 12, similarly to that described at the output of the adder 7, a centered random process takes place (Fig. 2k and 3). In this case, the noise voltage is of opposite polarities, while the useful signal

and the remains of the UE are unipolar pulses. Using this distinction with the help of a nonlinear element 8. for example, a diode, it is possible to obtain at the input of a voltage delay line 9

only the intensity of the noise interference (Fig.2l).

When a pulse noise voltage arrives at the input of the delay line 9, a response appears at each of its m outputs,

the total delay time being 2 gi. During this time, m multiplication blocks (block 10) and adder 11 perform weight summation of noise pulses in order to isolate them

mean value. The feed to the second inputs of each of the m block multipliers is 10 identical coefficients equal to 1 / m. due to the necessity of summing in block 11 the normalized noise components.

After weighting with blocks 9-11 of the output voltage of the nonlinear element 8, the output of the adder 11 is removed, the voltage corresponding to

the intensity of noise interference (Fig.2l. shown by the dotted line). Thus, as a result of the proposed processing of the C + W + UU mixture, the influence of the useful signals of 14 UE on the measurement of

Ears

Mathematical modeling of devices assembled according to known and proposed schemes shows that the absolute error in measuring the intensity of noise interference for a known device is determined by the formula Ai Uc C -m. and for the proposed device - according to the formula LS 1 RV C r. Where Uc is the amplitude of the useful impulse

signal; С - proportionality coefficient: m - number of taps of delay line 9; 1pr - reverse current of nonlinear element; RH is the load resistance of the nonlinear element 8.

Hence the relative error in measuring the noise interference intensity

   arr rh, l

 ST - IL (1;

Obviously, to reduce the value of 5, it is necessary to reduce the value of 1oBp at constant load of the element 8. When using as element 8, for example, the diode D18 and with Uc 1 V and the input resistance of the line 9 delay RH 10 kOhm1o5r 50 -10 A. (( ,five.

Thus, for this example, the accuracy of measuring the intensity of noise interference offered by the proposed device is 2 times compared with the known one.

Analysis of expression (1) shows that, in the general case, when measuring the intensity of noise interference against the background of useful signals, the potential accuracy of the proposed device is high.

Claims (1)

Invention Formula An instrument for measuring noise interference with the detector, the line z 71, ep / -1.k; with m taps1 ;. m blocks multiplying the outputs of which are connected to the inputs of the first adder, the second adder, characterized by that. that, in order to improve the accuracy of measuring the noise intensity, the first and second delay elements connected in series, a voltage divider, a subtraction unit and a module charging unit are introduced in it, the output of which is connected to the first summing input The second adder, as well as the nonlinear element and the second voltage divider, the detector output through the second voltage divider connected to the second input of the subtractor and the first subtractive input of the second adder, the output of which through the nonlinear element is connected to the input of the delay line, each of m taps which is connected to the corresponding input of one of the m multiplication blocks, with This output of the noise intensity measurement device is the output of the first adder, and the input is the detector input, the output of which is connected to the second summing input of the second adder through the first delay element, the second subtracting input of which is connected to the output of the first voltage divider. k ... g S & iifod Fig. /