CN109406089B - Cut-off frequency gear rapid detection device of signal conditioner - Google Patents
Cut-off frequency gear rapid detection device of signal conditioner Download PDFInfo
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- CN109406089B CN109406089B CN201811294187.5A CN201811294187A CN109406089B CN 109406089 B CN109406089 B CN 109406089B CN 201811294187 A CN201811294187 A CN 201811294187A CN 109406089 B CN109406089 B CN 109406089B
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Abstract
The invention discloses a cut-off frequency gear rapid detection device of a signal conditioner, which comprises a signal injection module, a signal measurement module, a signal switching module and a central processing unit, wherein the signal injection module is used for providing a signal source for the signal conditioner; the device can check and confirm the cut-off frequency of the signal conditioning equipment before the wind tunnel test, and avoids the problem that the signal of the measuring system cannot be filtered according to the expected gear during the wind tunnel test due to the change of the gear of the cut-off frequency caused by human factors or the self-reason of the equipment, thereby influencing the test quality. In addition, after the abnormity occurs, the problems of low efficiency of manual reinspection and abnormal troubleshooting are avoided, and the data quality and the test capability of the wind tunnel measurement system are guaranteed.
Description
Technical Field
The invention belongs to the field of electronic signal monitoring, and particularly relates to a cut-off frequency gear rapid detection device of a signal conditioner in a wind tunnel measurement system.
Background
The signal conditioner is one of core devices of a measuring system in a wind tunnel test, and the performance of the device inevitably affects the result and quality of the wind tunnel test. Due to human errors or abnormal reasons of equipment in the process of using the signal conditioner, the working gear of the cut-off frequency of the signal conditioner is abnormal, so that a front-end signal to be processed is filtered in an error mode, a rear-end measurement system acquires a large amount of noise and interference data, and the quality and reliability of a wind tunnel test are damaged.
Disclosure of Invention
The invention aims to provide a cut-off frequency gear rapid detection device of a signal conditioner under the condition of the prior art, according to the filtering cut-off gear currently set by the signal conditioner to be detected, an alternating voltage signal with certain amplitude and frequency is loaded and input at the front end of equipment by using the device, and the signal output at the rear end of the signal conditioner is automatically collected. And calculating and analyzing the acquired data according to a preset algorithm in an on-board chip to obtain whether the cut-off frequency working gear of the signal conditioner is consistent with the actually set gear, and finally outputting the result to an upper computer of the wind tunnel measurement system and a wind tunnel tester in a liquid crystal screen of the device through an external communication interface for checking.
In order to achieve the purpose, the invention adopts the following technical scheme:
a cut-off frequency gear rapid detection device of a signal conditioner is used for detecting the cut-off frequency of the signal conditioner during working and comprises a signal injection module, a signal measurement module, a signal switching module and a central processing module, wherein the signal injection module is used for providing a signal source for the signal conditioner, the signal measurement module of the signal conditioner is used for collecting an output signal of the signal conditioner, the signal switching module of the signal conditioner is used for switching different input channels between the signal injection module and the signal conditioner, and the central processing module of the signal conditioner exchanges signals with the signal injection module, the signal measurement module and the signal switching module and controls the measurement, loading and excitation of the signals.
In the above technical solution, the cut-off frequency gear rapid detection process is as follows:
the signal conditioner comprises the following steps: the signal injection module is connected to the input end of each channel of the signal conditioner, and the output end of the signal conditioner is connected to the signal measurement module;
the signal conditioner comprises the following steps: inputting the current cut-off frequency gear of each channel of the input signal conditioner through the central processing module;
the signal conditioner comprises the following third step: when the device enters automatic rapid detection, a signal injection module outputs a voltage signal according to certain voltage and frequency;
the signal conditioner comprises the following steps: the signal measurement module continuously collects input and output signals of the front end and the rear end of the measured signal conditioner during the signal injection period;
the signal conditioner comprises the following steps: stopping injecting and collecting signals, and calculating and judging the actual cut-off frequency gear of the current channel of the current measured signal conditioner according to the collected signals;
the signal conditioner comprises the following steps: and outputting the actual cut-off frequency gear detection result of the signal conditioner.
In the above technical solution, if there are multiple signal conditioner channels to be detected, repeating the steps three to five for multiple times to complete the detection of each channel.
In the technical scheme, the gear judgment of the channel in the signal conditioner is determined by alpha and beta; alpha represents the filtering coefficient or the reflection of the quality of the front and back end signals of the filter after the 1 st group of signals are loaded on the filter; beta represents the reflection of the filter coefficient or the quality of the front and back end signals of the filter after the 2 nd group of adding signals are loaded on the filter;
the closer the value of alpha or beta is to 1, the more the value of alpha or beta is, the filtering effect on the loaded signal is poor or the filtering effect on the loaded signal is not good under the filtering gear set by the current filter; the closer to 0, the better the signal is filtered or the better the filtering effect is;
in fact, the above method is to make the mean square of the signal, and the root-mean-square (root mean square) is the root mean square (root mean square), that is, the effective value of the ac signal is obtained;
if the effective value of the front end of the filter becomes lower after being filtered by the filter (the ratio of the rear effective value to the front effective value is less than 0.9), the filter has the function of filtering; if the effective value is unchanged after filtering by the filter (the ratio of the back effective value to the front effective value is greater than 0.9), it indicates that the filter does not filter the signal or the filtering level is too low.
In the above technical solution, when the signal conditioner is in a low-pass filtering mode:
if alpha is more than or equal to 0.9 and beta is less than 0.9, the cutoff frequency gear of the current signal conditioner is at aiIn the gears, a is the gear of the filter, i is a natural number, and the filters generally on the market have a plurality of fixed filter frequency gears, such as 1Hz, 10Hz, 100Hz and the like;
if alpha is more than or equal to 0.9 and beta is more than or equal to 0.9, the gear ratio a represents the cut-off frequency gear ratio of the current signal conditioneriLarge at aj(j > i) in the gear, assuming the filter gear is 1, 10, 100, 200, 300, the current filter gear is 100, i is i;
then there is j e [3,4 ∈]Namely aj∈[200,300]；
Then there is K e [1,2 ]]Namely ak∈[1,10]；
If alpha and beta are not in the interval of alpha being more than or equal to 0.9 and beta being less than 0.9 and alpha being more than or equal to 0.9 and beta being more than or equal to 0.9, the step ratio a represents the cut-off frequency of the current signal conditioneriSmall at akAnd (k < i) gear.
In the above technical solution, when the signal conditioner is in a high-pass filtering mode:
if alpha is less than 0.9 and beta is more than or equal to 0.9, the cutoff frequency gear of the current signal conditioner is at aiOn the gear; if alpha is more than or equal to 0.9 and beta is more than or equal to 0.9, the gear ratio a represents the cut-off frequency gear ratio of the current signal conditioneriSmall at aj(j < i) gear;
if alpha and beta are not in the interval of alpha less than 0.9 and beta more than or equal to 0.9, and alpha more than or equal to 0.9 and beta more than or equal to 0.9, the gear ratio a represents the cut-off frequency of the current signal conditioneriLarge at akAnd (k > i) gear position.
In the above technical solution, the α and β are obtained by the following processes:
step A: recording the filtering gear of the current signal conditioner as ai(ii) a The next filtering gear is marked as ai+1Providing two AC signal inputs of different frequencies;
and B: for the first alternating current signal, the collected front end signal of the signal conditioner is marked as XiAnd the back-end signal is marked as Yi；
For the second AC signal, the collected signal at the front end of the signal conditioner is marked as XjAnd the back-end signal is marked as YjThe number of the signals acquired each time is limited to n, wherein n is more than or equal to 200;
and C: the four sets of signals in step C are squared and summed,
then dividing the summation data by the number n of the signals respectively to obtain the average value of each group of signals,
avg1＝S1/n、avg2＝S2/n、avg3＝S3/n、avg4＝S4/n；
α＝avg2/avg1；β＝avg4/avg3。
in summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:
the device can check and confirm the cut-off frequency of the signal conditioner before the wind tunnel test, and avoids the problem that the signal of the measuring system cannot be filtered according to the expected gear during the wind tunnel test due to the change of the cut-off frequency gear caused by artificial reasons or self reasons of equipment, thereby influencing the test quality. In addition, after the abnormity occurs, the problems of low efficiency of manual reinspection and abnormal troubleshooting are avoided, and the data quality and the test capability of the wind tunnel measurement system are guaranteed.
Drawings
The invention will now be described, by way of example, with reference to the accompanying drawings, in which:
FIG. 1 is a block diagram of the internal hardware components of the apparatus of the present invention;
fig. 2 is a schematic diagram of the connection used in the present invention.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
As shown in fig. 1, the inventive device is mainly composed of four main modules: the device comprises a signal injection module, a signal measurement module, a signal switching module and a central processing module.
A signal injection module: the signal injection module provides a voltage signal with a certain index, and the voltage signal is a signal source at the front end of a signal conditioner of the wind tunnel measurement system; meanwhile, the signal injection module can provide other electric signals and can be selected according to requirements (including measuring range and precision requirements); the signal injection function can be implemented with a function generator or standard signal source equipment.
A signal measurement module: the signal measurement module can collect the output signal of the signal conditioner and transmit the result to the central processing module; the signal acquisition function can be realized by using a digital multimeter or a dynamic signal acquisition card.
The signal switching module: as the signal conditioner in the wind tunnel measuring system usually has 10 signal input channels, and each channel can be respectively and independently set to different filtering cut-off frequencies. Therefore, in the signal injection process, different signals need to be injected for detection according to the filtering cutoff frequencies set by different channels, and therefore a signal switching module needs to be equipped to switch different test signals to different channels. The module needs to meet the signal switching function of 10 channels; in order to ensure the test precision and reliability, only one standard signal is switched and injected into the tested signal conditioner at the same time; in order to ensure the test precision and reliability, the output signal of only one signal conditioner is switched to the signal measurement module of the device at the same time;
a central processing module: the module can pass through bus, serial port and G for the three modulesIControlling the PB or LAN port to obtain corresponding signal acquisition result, calculating the acquired data, and analyzing and judgingAnd the fruits are notified to the upper computer through the LAN port. The above functions can be realized by an embedded industrial personal computer or a controller. The module loads a built-in algorithm after acquiring the filtering cut-off frequency of each channel set by the panel to obtain the specific voltage amplitude and frequency required to be output by the signal injection module; the control signal switching module is used for switching the injection signal to a specified signal conditioner channel and switching a channel feedback signal to the signal measuring module; the control signal measurement module measures and collects signals and obtains measurement results from the signal measurement module; and calculating and analyzing the obtained measurement result according to a built-in algorithm, and pushing the result to a display panel or a communication interface.
The connection schematic diagram of the detection device is shown in fig. 2, and the whole detection process is as follows:
a) the signal injection joint of the device is connected to the input end of each channel of the signal conditioner, and the output end of the signal conditioner is connected to the acquisition and measurement end of the device;
b) inputting the current cut-off frequency gear of each channel of the signal conditioner in a panel of the device;
c) after the connection and the setting are confirmed to be finished, the device is started to carry out automatic and rapid detection;
d) the signal injection module outputs a voltage signal according to certain voltage and frequency;
e) the signal measurement module continuously collects input and output signals of the front end and the rear end of the measured signal conditioner during the signal injection period;
f) stopping injecting and collecting signals;
g) calculating and judging the actual cut-off frequency gear of the current channel of the current measured signal conditioner according to the collected signals;
h) if a plurality of signal conditioner channels need to be detected, the device automatically repeats the steps d) to g);
i) and outputting the actual cut-off frequency gear detection result of each channel of the signal conditioner to a user.
The gear of each channel of the signal conditioner is calculated as follows:
1) recording the current signal conditioner filtering gear set as a ═ a1,a2,a3,….am](ai+1The filter frequency is greater than aiFrequency filter)
2) Recording the filtering gear of the current signal conditioner as ai(ii) a The next filtering gear is marked as ai+1；
3) Two alternating current signals loaded by the device are as follows:
signal 1: voltage 5V, frequency ai/2Hz；
Signal 2: voltage 5V, frequency ai+(ai+1-ai)/2Hz；
Note: the signal amplitude, namely the voltage, can be adjusted according to the measuring range of the acquisition equipment;
4) the number of the signals collected by the device is limited to n, wherein n is more than or equal to 200;
5) the signal 1 at the front end of the signal conditioner collected by the device is recorded as XiAnd the back-end signal is marked as Yi(ii) a The collected front end signal 2 of the signal conditioner is recorded as XjAnd the back-end signal is marked as Yj；
6) The 4 sets of signals are squared and summed, i.e.:
·
·
·
·
7) 4 pieces of summation data S1,S2,S3,S4Dividing by n respectively to obtain the mean value after evolution of 4 groups of signals:
·avg1＝S1/n；
·avg2＝S2/n；
·avg3＝S3/n；
·avg4＝S4/n；
8) calculating α ═ avg2/avg1；β＝avg4/avg3And drawing a conclusion after the following judgments:
if alpha is greater than or equal to 0.9 and beta is less than 0.9, it represents that the cut-off frequency gear of the current signal conditioner is at aiOn the gear;
if alpha is greater than or equal to 0.9 and beta is greater than or equal to 0.9, it represents the current cut-off frequency step ratio a of the signal conditioneriLarge at aj(j > i) gear;
if alpha, beta are not in the interval of alpha ≧ 0.9 and beta < 0.9, and alpha ≧ 0.9 and beta ≧ 0.9, this represents the current signal conditioner cut-off frequency step ratio aiSmall at akAnd (k < i) gear.
9) Note: the above-mentioned judgment conditions assume that the signal conditioner is in a low-pass filtering mode. If the device is in a high-pass filtering mode:
if alpha < 0.9 and beta ≧ 0.9, this means that the current signal conditioner cut-off frequency range is at aiOn the gear;
if alpha is greater than or equal to 0.9 and beta is greater than or equal to 0.9, it represents the current cut-off frequency step ratio a of the signal conditioneriSmall at aj(j < i) gear;
if alpha, beta are not in the interval of alpha < 0.9 and beta ≧ 0.9 and alpha ≧ 0.9 and beta ≧ 0.9, this represents the current signal conditioner cut-off frequency step ratio aiLarge at akAnd (k > i) gear position.
The invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification and any novel method or process steps or any novel combination of features disclosed.
Claims (6)
1. A cut-off frequency gear rapid detection device of a signal conditioner is used for detecting the cut-off frequency of the signal conditioner during working and is characterized by comprising a signal injection module, a signal measurement module, a signal switching module and a central processing module, wherein the signal injection module is used for providing a signal source for the signal conditioner, the signal measurement module is used for collecting an output signal of the signal conditioner, the signal switching module is used for switching different input channels between the signal injection module and the signal conditioner, and the central processing module exchanges signals with the signal injection module, the signal measurement module and the signal switching module and controls the measurement, loading and excitation of the signals;
the quick detection process of the cut-off frequency gear comprises the following steps:
the method comprises the following steps: the signal injection module is connected to the input end of each channel of the signal conditioner, and the output end of the signal conditioner is connected to the signal measurement module;
step two: inputting the current cut-off frequency gear of each channel of the signal conditioner through the central processing module;
step three: when the device enters automatic rapid detection, a signal injection module outputs a voltage signal according to certain voltage and frequency;
step four: the signal measurement module continuously collects input and output signals of the front end and the rear end of the measured signal conditioner during the signal injection period;
step five: stopping injecting and collecting signals, and calculating and judging the actual cut-off frequency gear of the current channel of the current measured signal conditioner according to the collected signals;
step six: and outputting the actual cut-off frequency gear detection result of the signal conditioner.
2. The apparatus as claimed in claim 1, wherein if there are multiple channels of signal conditioner to be tested, repeating the steps three to five for multiple times to complete the testing of each channel.
3. The apparatus of claim 1, wherein the channel of the signal conditioner has a shift determination determined by α and β, wherein α represents the filter coefficient of the front and back signals after the first set of signals is applied to the filter; β is the filter coefficient representing the front and back signals of the filter after the second set of signals is applied to the filter.
4. The device as claimed in claim 3, wherein when the signal conditioner is in low-pass filtering mode:
if alpha is more than or equal to 0.9 and beta is less than 0.9, the cutoff frequency gear of the current signal conditioner is at aiIn the gear, a is the gear of the filter, and i is a natural number;
if alpha is more than or equal to 0.9 and beta is more than or equal to 0.9, the gear ratio a represents the cut-off frequency gear ratio of the current signal conditioneriLarge at ajIn the gear, j is a natural number, and j>i；
If alpha and beta are not in the interval of alpha being more than or equal to 0.9 and beta being less than 0.9 and alpha being more than or equal to 0.9 and beta being more than or equal to 0.9, the step ratio a represents the cut-off frequency of the current signal conditioneriSmall at akIn the gear, k is a natural number and k < i.
5. The device for rapidly detecting the cut-off frequency range of the signal conditioner as claimed in claim 3, wherein when the signal conditioner is in a high-pass filtering mode:
if alpha is less than 0.9 and beta is more than or equal to 0.9, the cutoff frequency gear of the current signal conditioner is at aiOn the gear;
if alpha is more than or equal to 0.9 and beta is more than or equal to 0.9, the gear ratio a represents the cut-off frequency gear ratio of the current signal conditioneriSmall at ajIn the gear, j is less than i;
if alpha and beta are not in the interval of alpha less than 0.9 and beta more than or equal to 0.9, and alpha more than or equal to 0.9 and beta more than or equal to 0.9, the gear ratio a represents the cut-off frequency of the current signal conditioneriLarge at akIn the gear, k is larger than i.
6. The apparatus for rapidly detecting the cut-off frequency range of a signal conditioner as claimed in any one of claims 3 to 5, wherein α and β are obtained by:
step A: recording the filtering gear of the current signal conditioner as ai(ii) a The next filtering gear is marked as ai+1Providing two AC signal inputs of different frequencies;
and B: for the first alternating current signal, the collected front end signal of the signal conditioner is marked as XiAnd the back-end signal is marked as Yi；
For the second AC signal, the collected signal at the front end of the signal conditioner is marked as XjAnd the back-end signal is marked as YjThe number of the signals acquired each time is limited to n, wherein n is more than or equal to 200;
and C: the four sets of signals in step B are squared and summed,
then dividing the summation data by the number n of the signals respectively to obtain the average value of each group of signals,
avg1＝S1/n、avg2＝S2/n、avg3＝S3/n、avg4＝S4/n；
α＝avg2/avg1；β＝avg4/avg3。
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