RU2250494C1 - Hardware-software device for multichannel conversion and recording of analog signals - Google Patents

Abstract

FIELD: electronic engineering.

SUBSTANCE: for each channel device has digital signal converter, block for setting conversion digitization frequency, conversion level adjustment block, block for transferring electric signals to physical values, block for observing converted signals, block of precision of signal conversion, block of signal conversion time, block for disabling unused channels, block for synchronization of analog signals, visualization block, converted signal recording block. Device allows to convert signals of different levels, to change digitization frequency and conversion time, to disable unused channels, transfer sensors signals to physical values with consideration of sensors scales, observe signals at different scales, appropriate to levels of converted signals, to measure precision of recording of converted signals.

EFFECT: higher efficiency.

5 dwg

Description

The invention relates to measuring equipment, and in particular to devices that register signals from electrical sensors, and can be used to register various electrical signals.

In many branches of technology there is a need to register analog signals from electrical sensors. For this purpose, analog and digital devices have been created that allow recording the analog signals coming from them.

With the help of electric sensors, many measurements are made, in particular, the pressure in the stream and its pulsation are measured. For example, electric pressure pulsation sensors are widely used in testing aircraft engines. Similar devices are used when testing and refining compressors.

The tendency to increase the loading of compressor stages and a corresponding increase in peripheral speeds and rotational speeds leads to an expansion of the frequency range of measurements. In particular, when conducting studies aimed at improving the efficiency of compressor stages and incorporating stages with a supersonic flow rate in relative motion, it is necessary to increase the accuracy and information content of the measured parameters, when conducting measurements, use low-inertia electric sensors with a frequency range of up to 100 kHz, have appropriate modern devices for collecting analog data, their digital conversion and subsequent processing of the received data. So, when visualizing the flow structure in the flow part of compressors by measuring pressure pulsations with low-inertia sensors, followed by the construction of isobars, synchronous multi-channel recording of analog signals coming from them is required.

Known is “Analog Magnetic Device A2-1214 / A2-914”, manufactured by SONY Magnescale Inc, which is a 14-channel magnetic recorder and records signals on magnetic tape.

The disadvantage of this device is the need to use additional units for digital conversion of the analog signal during secondary processing. In addition, this magnetic device has a frequency range of 0 ... 40 kHz, which limits its scope.

The “MSX16 Multichannel Digital Device” is known, which provides the “Multilevel Digital Diagnostic System for GTE”, presented in the US security document No. N 1006, G 01 B 7/16, 03/27/1990, by collecting analog data from tensometers or other electrical sensors.

The disadvantage of this technical solution is the limitation of the frequency range (Δf = 0 ... 25 kHz) and the inability to synchronously poll the sensors used.

The closest technical solution to the claimed and adopted as a prototype is “Digital device SIR-1000W”, the catalog “PRODUCT CATALOG 2003”, which has a multi-channel input and allows sequential polling of electrical sensors, while the sampling frequency decreases in proportion to the number of channels used. So it has a frequency range of 160 kHz with a 4-channel input, 80 kHz with an 8-channel input and 40 kHz with a 16-channel input.

The main disadvantage of this device is the limitation on the sampling rate and its decrease with an increase in the number of polled channels, as well as the inability to organize synchronous reading of analog data from a large number of sensors. The lack of these capabilities does not allow the use of this device to build instantaneous pressure isolines in the channels of the rotating impellers of the compressor, nor does it allow synchronous interrogation of low-inertia pressure sensors when used to study unsteady and unstable processes that occur, for example, in an aircraft engine and compressor.

The objective of the proposed technical solution is to increase the efficiency of the device by ensuring the accuracy and high sampling rate of the conversion and registration of multi-channel analog signals when they are simultaneously received from low-inertia sensors.

The technical result is achieved in the inventive hardware-software device, which allows multichannel conversion of analog signals synchronously arriving from signal sources. For this, the hardware-software device is equipped with a block for adjusting the signal conversion level for each channel, a unit for setting the sampling frequency of the conversion of incoming signals, a unit for converting electrical signals into physical quantities, a unit for monitoring the converted signals, a unit for converting the signal accuracy, a unit for signal conversion duration, a shutdown unit unused channels, a signal registration unit, an analog signal synchronization unit, while the control unit the signal level for each channel is connected to the conversion sampling frequency change unit, which is connected to the signal monitoring unit and to the unused channel disconnection unit, and the signal conversion accuracy unit is connected to the signal conversion duration setting unit, the unit for converting electrical signals to physical quantities is connected with a signal recording unit and with an analog signal synchronization unit.

The pulsations of static and total pressures, measured by fixed low-inertia sensors in the compressor stages, have a broadband, polyharmonic composition. The frequency of the first harmonic of the variable pressure signal is equal to the repetition frequency of the blades, the frequency of the second and subsequent harmonics of the signal reflects the nature of the pressure changes in the interscapular channels, the structure of traces and disturbances in the flow created by the rotation of the impeller. To analyze the nature of processes in interscapular channels, it is sufficient to have information in the frequency spectrum, including the fifth harmonic of the signal. With a rotor speed of 200 Hz and the number of blades on stage 50, this corresponds to a frequency of 100 kHz.

Currently, analog signals from low-inertia pressure sensors are recorded using multichannel magnetic devices having a frequency range of 40 kHz (with a dynamic error of ± 12%), which ensures satisfactory averaged and instantaneous flow patterns determined by pressure isolines in each interscapular channel of the workers compressor wheels.

The construction of pressure isolines is performed using a complex of programs tied to a special computer having a multi-channel analog-to-digital converter with a limited sampling frequency. Processing the readings of the sensors is done by sequentially introducing an analog signal recorded by each of the sensors. This method of entering information is a lengthy process and allows the construction of contours only after testing. In addition, this method of collecting and processing information requires the additional introduction of a system of clock pulses, which reduces the possibility of introducing a useful signal.

To move to a more modern system of collecting and processing low-inertia data with higher accuracy and resolution, you need a device that provides high resolution digital conversion of an analog signal and input it into a computer.

The duration of one rotation of the rotor is hundredths and thousandths of a second, and the time it takes for one blade to be 100 times less, and to observe the separation of the boundary layer having a thickness commensurate with the thickness of the profile, it is necessary to have several points on the time interval Δt = 1 ... 3 μs. During measurements, as experience shows, it is impossible to predict in advance the shape of the signal coming from a particular sensor. Therefore, the sampling frequency should be high enough to ensure high quality signal conversion of any shape. When studying the flow flow in the compressor stages, in order to increase the informativeness of the measurement system and to obtain a more complete picture of the changes that occur in the flow structure in individual channels of the compressor impeller when the operating mode changes in flow and speed, the signal registration should provide the required number of points per step the interscapular channel of the compressor impeller.

The flow structure is multi-zone and contains shock waves, as well as vortices formed and converging as a result of flow separation inside the channel and in the wake of the blades. When digitally recording an analog signal at each point along the compressor path, this condition must be met. This is especially important when there is an unstable flow around the blades, for example, near the boundary of stable operation, since in this case it is necessary to consider the instantaneous flow patterns, and the averaged flow patterns give an incorrect idea of the processes occurring in the wheel.

In this regard, to study non-stationary effects, it is necessary to synchronously read the signal from the sensors in order to avoid an erroneous idea of changes in the flow, which can occur due to a phase shift.

The inventive hardware-software device for multi-channel conversion of analog signals has standard boards that provide signal conversion with a resolution of 12 bits. Connecting such devices to a personal computer allows you to get a multi-channel converter and analog signal recorder. Board synchronization is carried out by a special program.

The inventive hardware-software device for multichannel conversion and registration of analog signals allows you to:

- convert a signal of various levels;

- change the sampling frequency of the conversion in the range Δf = 1000 ... 1,000,000 Hz;

- translate electrical pulses into physical quantities, taking into account the static calibrations of each of the sensors;

- observe the signal in various scales corresponding to the level of the converted signal;

- change the recording accuracy of the converted signal;

- change the duration of the conversion;

- disable unused channels;

- register the signal without taking into account the DC component.

All these functions are provided by special software blocks, the action of which is initiated by the corresponding buttons.

Figure 1 shows a diagram of the inventive hardware-software device for multi-channel conversion of analog signals.

Figure 2 shows a view of the signal from the transverse pulse sensor that occurs during the sequential passage of revolutions, converted using a hardware-software device.

Figure 3 shows a view of the signals coming from two low-inertia pressure sensors that are installed above the working blade during the sequential passage of two adjacent channels, and converted using a hardware-software device.

Figure 4 shows a view of the signals that occur in the full sensor and the static pressure sensor in the nozzle to determine the ripple of the speed, converted using a hardware-software device.

Figure 5 shows a signal from a pulse sensor of the repetition frequency of the blades of the impeller of the compressor, arising from the sequential passage of two adjacent blades and converted using a hardware-software device.

The hardware-software device for multi-channel conversion and registration of analog signals, the circuit of which is shown in Fig. 1, contains sensors 1-12 analog signals, a unit 13 for specifying a sampling rate for converting the incoming signals, a unit 14 for adjusting the signal conversion level for each channel, a translation unit 15 electrical signals to physical quantities, block 16 monitoring the converted signals, block 17 accuracy of the signal conversion, block 18 the duration of the signal conversion, block 19 off unused channels, block 20 registration signals, block 21 synchronization of analog signals. In this case, the analogue signal sensors 1-12 are connected to the block 13 for setting the sampling frequency of the conversion of the incoming signals, with the block 14 for adjusting the signal conversion level for each channel, as well as with the block 15 for converting electrical pulses into physical quantities and with the block 16 for monitoring the converted signals, with a block 17 that sets the accuracy of the conversion, which, in turn, is connected with the block 18 of the duration of the conversion and with the block 19 disconnecting unused channels, as well as with the block 20 of the registration signals and block 21 signal synchronization.

The hardware-software device for multichannel conversion of analog signals works as follows:

Before starting work, set the parameters of the conversion, such as the sampling rate, the number of points in the implementations, the number of decimal places in the numbers after the conversion. The beginning of the operation of the units connected to the computer is carried out by pressing the “start” key, after which the visualized signals from the connected measuring electrical devices are viewed. If necessary, make a change in the signal level and the corresponding change in the settings of the scales in the windows of the oscilloscope (not shown in the diagram). In accordance with the tasks to be solved during the research and the nature of the recorded processes, choose the mode of conversion of signals that meets the requirements:

- take into account or do not take into account the constant component;

- take into account or not the coefficients that convert electrical signals into physical quantities;

- make switching the signal level.

File recording is performed in Microsoft Excel in the dialogue mode.

The inventive hardware and software device for multichannel conversion and registration of analog signals using ready-made analog-to-digital converters and a personal computer for synchronous multichannel conversion and registration of analog signals for their subsequent secondary processing allows the construction of pressure isolines in the flow part of the compressor to study the unsteady flow structure. At the same time, the frequency range of the measurement system is expanded. Also, this device allows the study of the flow structure in compressors having a high rotational speed and a high repetition rate of the blades. Moreover, it surpasses the previously used analog data recording devices, for example, using an analog magnetic multichannel device and processing the obtained data using a special computer, in the range of operating frequencies exceeding more than 25 times and by the same amount of accuracy in converting analog signals, and at the same time, digital multi-channel registration of signals of any electrical sensors is performed synchronously.

Claims (1)

A hardware-software device (APU) for multi-channel conversion and registration of analog signals, including a signal source, digital signal converter, converted signal visualization unit, converted signal registration unit, secondary processing unit, characterized in that it is equipped with a sampling frequency setting unit for all channels conversion of incoming signals, a unit for controlling the level of signal conversion for each channel, a unit for converting electrical signals into physical ones values, by the unit for monitoring the converted signals, the unit of accuracy of the signal conversion, the unit of the duration of the signal conversion, the unit for disconnecting unused channels, the unit for registering signals, the unit for synchronizing analog signals, while the unit for adjusting the signal level for each channel is connected to the unit for changing the sampling frequency of the conversion, which connected to the signal monitoring unit and the unused channel disconnection unit, while the signal conversion accuracy unit with It is connected to a unit for setting the duration of signal conversion, and the unit for converting electrical signals into physical quantities is connected to a signal registration unit and an analog signal synchronization unit.

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