Single stochastic meter gain (options)

 

The invention relates to the field of electrogravimetry and can be used in problems of measurement amplifiers low frequency, such as audio amplifiers. The meter in the first embodiment comprises a generator of white noise, the filtering unit, a detector, an analog-to-digital Converter, accumulating adder and functional Converter. The meter according to the second variant comprises a generator of white noise, the filtering unit, a squarer, analog-to-digital Converter, accumulating adder and functional Converter. The invention is directed to improving the accuracy of measurements. The device allows to measure the gain as throughout the operating frequency range of the amplifier, and in a separate spectral Windows. This takes into account the nonlinear distortion products, accompanying the work of the real amps. 2 N. p. F.-ly, 2 Il.

The invention relates to the field of electrogravimetry and can be used in problems of measurement amplifiers low frequency, such as audio amplifiers.

As a prototype of the selected device containing two managed amplifier-limiter, two detectors and two fnname the input device, the outputs of the first and second amplifiers respectively connected to the inputs of the first and second detectors, the outputs of which are connected to the inputs respectively of the first and second filters are low pass outputs which are output devices, control inputs of the amplifiers are combined and connected to the output of one of them [Goron I. E. the Radio. - M., Bond, 1979, page 221].

The principle of operation of the prototype allows to measure the gain, using as test signals real random processes, carrying useful information and passing through the monitoring path in the operating mode. Features of the prototype ensures that the work of the amplifier channel for the necessary measurements and make it effective as a tracking device for the specified parameter. The use of this device as a purely measuring device is impractical because of its low accuracy.

Technical result achieved when using the present invention is to improve measurement accuracy.

The technical result is achieved by the fact that in single-channel stochastic meter gain (option 1), containing the detector according to the invention introduced alternator brasovan, the output which is the output of the meter, test the output of which serves as the output of a white-noise generator, and a test input is the input of the filtering unit, the output of which through the detector is connected to the information input of the analog-to-digital Converter, the output of which is connected with the information input is accumulating adder, the output of which is connected to the functional input of the Converter.

The technical result can be achieved also by the fact that in single-channel stochastic meter gain (option 2) according to the invention introduced a white-noise generator, block filtering, analog-to-digital Converter, a squarer, accumulating adder and functional inverter whose output is the output of the meter, test the output of which serves as the output of a white-noise generator, and a test input is the input of the filtering unit, the output of which is connected to the information input of the analog-to-digital Converter, the output of which is connected to the input of the Quad, the output of which is connected with the information input is accumulating adder, the output of which is connected to the functional input of the Converter.

In Fig.1 and 2 shows the functional diagram of the two options, which I Fig.1 comprises a generator 1 white noise, the filtering unit 2, a detector 3, an analog-to-digital Converter (ADC) 4, accumulating adder 5, a functional Converter 6 and test the amplifier 7 with the load resistance RL. The output of the generator 1 white noise, which is the test output of the meter is connected to the input of the tested amplifier 7, the output of which is connected to the test input meter input unit 2 filter, the output of which through the detector 3 is connected to the information input ADC 4, the output of which is connected with the information input is accumulating adder 5, the output of which is connected to the functional input of the Converter 6, the output of which is output To the meter.

Functional diagram of the meter of Fig.2 comprises a generator 8 white noise, block 9 filtering, ADC 10, squarer 11, accumulating adder 12, the functional Converter 13 and the tested amplifier 14 with the load resistance RL. The output of the generator 8 white noise, which is the test output of the meter is connected to the input of the tested amplifier 14, the output of which is connected to the test input meter input unit 9 of the filter, the output of which is connected to the information input of the ADC 10, the output of which is connected to the input of Quad 11, the output catalogo Converter 13, the output of which is output To the meter.

As the test signal in the meter is used subconsultancy stationary ergodic random process with a uniform spectrum within a band of operating frequencies of the investigated amplifiers. This signal is conventionally refer to white noise, which is supplied from the generator 1, is also conventionally called the generator of white noise. From an engineering point of view, the generator 1 should be characterized by a high stability of parameters over time.

As can be seen from the functional circuit (Fig.1), random test signal u(t) after amplification in the test amplifier 7 is supplied to the filtering unit 2, where it is allocated a given bandwidth. The received signal is detected in block 3, and then enters the ADC 4. ADC output 4 times, uo(tn) forwarded to the accumulating adder 5, which for a time T equal to the observation interval, is the sum of

where N is the number of samples during the observation time T;

, (n=1,2,...,N);

t is the sampling period (repetition period of the clock pulses on strike is ficient gain() amplifier 7 amount (1) should be divided by the same amount, but obtained when the gain with the pre-known value - in our case, when the reference value K()=1. The sum received by It()=1, we denote as S0and put in the reference code as a permanent divider in functional Converter 6. The mathematical form of the values of S0looks like this:

where, (n=1,2,...,N);

t02- the initial time instant;

- digitized samples of the signal obtained after filtering and detection of a random signal u(t).

Thus, the expression for the desired gain(), which defines the gain in a bandwith center in the pointwill be:

In order to ensure fidelity to the assertion (3), we note that the sum of (1) and (2) differ from srednenapryazhennyh values Uoand U0related to the previous filtering random �614.gif">

Therefore, the ratio srednenapryazhennyh values Uoafter amplification and U0to gain that (attitude) represents the gain K(), is the ratio of the accumulated value of Soand S0:

Given that sredneotraslevye values of a stationary process with time are independent, then the relation (5) also does not depend on time, provided that the gain K() does not change. In other words, the relation (5) does not depend on what times were measured value of Soand S0. This means that adopted us as a reference value of S0could be measured or calculated in advance, prior to the meter and recorded as a constant factor (or divisor) in case the reference value functional Converter 6, which, as can be seen from the above material is intended to perform the operation of dividing the sum Soon a constant divisor of S0.

From the principle of operation of the meter (see Fig.1) it is clear that the accuracy of measurement of K() will depend on the stability of the parameters of the generator 1, that is, from tog is correctly fixed. And first of all it is necessary to emphasize the constancy in time of the variance process. In addition to the use of special measures for the stabilization of the parameters of the random process variant a preliminary calibration of the meter, high efficiency and no additional costs. Calibration should be performed before each series of measurements, and the implementation of it boils down to the fact that the test connector input and output instead of the amplifier 7 is connected a jumper (not shown). As a result, after time T the output function of the Converter is the obtained value representing a ratio srednetemperaturnogo values UTat this time interval, in these conditions to the reference value U0:

.

Measured this way, the value forand will be used as a correction factor, i.e. the evaluation of K*() it is necessary to Refine the result must be multiplied by another coefficient.

The accuracy of the measurements is also affected and the duration of the observation interval T=Nt (when synchronizing the beginning of the video, the adder 5 accumulates counts: of course, the larger T is, the smaller the error of the statistical evaluation. To determine the specific values of T should be based on the dynamic properties of the test signal. When the maximum interval correlationKthis process is T, it is recommended to choose from the condition T>>K.

The presence of the meter unit 2 enables to measure the gain is not only over the entire frequency range, in the form of a integral parameter K, but in the individual spectral Windows. The need to allocate bandwidthdue to the fact that in the absence of such opportunities, the measurement results can be strongly distorted, as the same sredneotraslevye values can have signals with different spectra. This means that two different investigated amplifier having a different amplitude-frequency characteristics will be described the same integral parameter K, as it will be referred to the entire frequency range, without regard to the gain distribution along the frequency axis.

When implementing block 2 in wind> the meter is easy to adjust and, if necessary, sequentially scanning the entire range of operating frequencies.

Variant of the meter shown in Fig.2 differs from the above device by the absence of the detector and the presence of a Quad. Introduction the operation of squaring (block 11), you can instead srednenapryazhennyh values to use for computing the values of dispersion processes. Thus, the operation of the meter differs as follows.

ADC output 10 times, uo(tn) is sent to a squarer 11, followed by the information input is accumulating adder 12, in which the end of the observation interval T is accumulated amount

In functional Converter 13 put pre-measured or calculated value - reference value:

where u0(tn- the samples at the output of the ADC at 10 K()=K0()=1.

The desired gain() is determined by the formula

The specified function (8) calculates the functional Converter 13, which is the same as before the - ADC 4 (10) storing the adder 5 (12) - the pulse sequence used for the clocking of the accumulating adder 5 (12), should be somewhat delayed relative to the same sequence that is supplied to the clock input ADC 4 (10): for a time sufficient to complete the transition process in the ADC 4 (10) associated with the update counts. Circuit clocking on the functional diagrams (Fig.1, 2) are not shown.

Claims

1. Single stochastic meter gain (option 1), containing the detector, characterized in that it introduced a white-noise generator, block filtering, analog-to-digital Converter, accumulating adder and functional inverter whose output is the output of the meter, test the output of which serves as the output of a white-noise generator, and a test input is the input of the filtering unit, the output of which through the detector is connected to the information input of the analog-to-digital Converter, the output of which is connected with the information input is accumulating adder, the output of which is connected to the functional input of the Converter.

2. Single stochastic meter gain (option 2), characterized in that in the first adder and functional Converter the output which is the output of the meter, test the output of which serves as the output of a white-noise generator, and a test input is the input of the filtering unit, the output of which is connected to the information input of the analog-to-digital Converter, the output of which is connected to the input of the Quad, the output of which is connected with the information input is accumulating adder, the output of which is connected to the functional input of the Converter.

 

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