Meter gain

 

The invention relates to the field of electrogravimetry and can be used for online measurement of gain broadband amplifiers and audio amplifiers, as well as for automated control paths passing audio signals. The device comprises two bandpass filter, two of the detector, two lowpass filter, two analog-to-digital Converter and functional Converter that performs in the simplest case, the division operation. The feature of the meter is that it does not require special test signals, and hence the generators of these signals. To measure the gain is sufficient to use a random source voltage of the input signal. You only need the presence in the spectrum of the source signal those frequency components that are configured bandpass filters of the meter. The technical result is to increase the accuracy of measurements. 1 Il.

The invention relates to the field of electrogravimetry and can be used for online measurement of gain broadband amplifiers and usilitel prototype device is selected, does not require special test signals and contains two managed amplifier-limiter, two detectors and two low pass filter (LPF), the inputs of the first and second amplifiers are respectively the first and second information 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 low-pass filter, the outputs of which are the output of the device control inputs of the amplifiers are combined and connected to the output of one of them [Goron I. E. the Radio. - M.: Communication, 1979, page 221].

A significant disadvantage of the prototype is the presence of two channels driven active analog circuits, the identity characteristics which largely affects the accuracy of the estimates of gain. Another disadvantage should include the form of the dependence of the output voltage of the device from the measured gain. Despite the linear mode, the transfer function is shifted. As a result, when the gain is unity, the output voltage of the amplifier is zero, and when the gain, the smaller the unit, the output voltage of me the AEB causes inconvenience in the application and requires the addition to the output voltage of the DC bias. The deficiencies noted, as a rule, limit the application of the prototype area associated with the monitoring of changes of gain, and not allow it to be used as a purely measuring device.

In addition, the prototype does not provide the ability to measure the gain as the frequency-dependent parameter. It compares sredneotraslevye values for the entire frequency range. Therefore, to measure the gain at a particular frequency (or band) this device does not allow. In some very real cases, this can lead to erroneous results, since signals with different spectra can have the same sredneotraslevye values.

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

The technical result is achieved by the fact that in the known meter gain, containing two detectors and two low pass filter, the outputs of the first and second detectors respectively connected to the inputs of the first and second low-pass filters, according to the invention introduced two bandpass filter, two analog-to-digital Converter and the functionality is OBRAZOVATEL connected respectively to the outputs of the first and second analog-to-digital converters, the inputs of the first and second analog-to-digital converters connected respectively to the outputs of the first and second low-pass filters, first and second information inputs of the meter are respectively the inputs of the first and second bandpass filters, the outputs of which are connected respectively to the inputs of the first and second detectors.

The invention is illustrated by the drawing, which shows a functional diagram of the meter gain.

Functional diagram contains two bandpass filter (PF) 1, 2, two of the detector 3, 4, two filters 5, 6 low pass (LPF), two analog-to-digital Converter (ADC) 7, 8, functional Converter 9 and test the amplifier 10 with a load resistance RL. The first information input of the meter is the entrance PF, the output of which through the detector 3 is connected to the input of low-pass filter 5, the output of which is connected to the information input ADC 7, the output of which is connected to the first input of the functional Converter 9, the output of which is output To the meter, the second information input of which is the entrance PF, the output of which through the detector 4 is connected to the input of low-pass filter 6, the output of which is connected to the information input of the ADC 8, the output ctablet clock input CLK of the meter. The input uI(t) investigated amplifier 10 is combined with the first information input of the meter, and the output uo(t) of the amplifier 10 is connected to the second information input of the meter.

The measurement process gain K() (module gear ratio) is as follows.

To input and output the analyzed amplifier 10 (see the drawing), which is in the operating mode amplification of the useful signal uI(t), connect the appropriate information inputs of the meter, as shown in the drawing. The input signal uI(t) from an external source is fed to the input of the first channel of the meter, where it is cut fairly narrow bandwidth; received signal u0(t) in the specified band is detected, that is, takes its module, and then averaged over the observation interval T. These operations, as it is easy to see from the functional circuit, performs band-pass filter 1, the detector 3 and the filter 5 lower frequencies, respectively. Similar actions are taken and on the output signal uo(t) of the amplifier is supplied to the second channel of the meter (PF 2 - detector 4 - LPF 6),

der="0">constant, we Express the signal at the output PF through the signal obtained at the output PF: u(t)=K()u0(t). Considering the introduced notation, we write the expressions for the signals at the outputs of the LPF 5 and FN respectively

and

The ratio of (1) and (2), which are nothing like sredneotraslevye the values of the input and output signals of the amplifier 10 in the band. equal to the gain K(in this band

what is easy to verify after basic cuts in the right part of equality (3). To calculate the relationship (3) value (1) and (2) digitized by the ADC 7, 8, and later in digital form are placed in a functional Converter 9, which performs the division operation (3).

The time constantfLPF 5, 6 should be chosen based on the maximum of the correlation intervaltosignals operating in a dedicated lane;&;to. In this case, the duration of integration T=fis becoming a lot moretoand sufficient to obtain unbiased estimates, firstly, and, secondly, the increase in T is generally useful to reduce errors averaging.

If the averaging function is fully vested, as suggested above, on the LPF 5, 6, the period of the clocking of the ADC 7, 8 should be selected based on the required conditions to update the output information. However, we cannot exclude the situation when engineering considerations to makeflarge enough it is difficult or even not possible, for example, due to the increased sizes of the elements RC-chains at low frequencies. In this case, when a relatively wide-band low-pass filter operation of averaging should be complete already in functional Converter in digital form. In this manner, the period of the clocking of the ADC 7, 8 should be selected based upon the requirements of the refresh rate of the output of the K*(fcan be greatly reduced and brought to a level, when talking about the integration and averaging low-pass filter 5, and 6 there will be no reason to, since the LPF 5, 6 will only protection function of ADC inputs from the high-frequency parasitic component, penetrating into the useful part of the spectrum. That is, the operation of averaging can be fully performed after analog-to-digital conversion, thereby removing the influence on the final result of neodenticula characteristics of analog filters 5, 6.

From the principle of the meter (see drawing) shows that it does not require a special test signal is rder="0">) it is enough to use a random source signal uI(t). You only need the presence in the spectrum of the source signal those frequency components that are configured bandpass filters 1, 2. As for their quality, i.e. bandwidthit is determined on the basis of specific tasks set before developed by the meter. For example, for automated control amplifier channel audio frequency at a frequency of 1 kHz, which can be used are considered meter, bandwidth is chosen equal to about 500-1000 Hz.

Claims

Meter gain, containing two detectors and two low pass filter, the outputs of the first and second detectors respectively connected to the inputs of the first and second low-pass filters, characterized in that it introduced two bandpass filter, two analog-to-digital Converter and functional inverter whose output is the output of the meter, and the first and second functional inputs of the Converter are connected respectively to the outputs of the first and second analog-to-digital conversion is pout and second low-pass filters, the first and second information inputs of the meter are respectively the inputs of the first and second bandpass filters, the outputs of which are connected respectively to the inputs of the first and second detectors.



 

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