the data acquisition systems
the automated testing systems
V.V. Shvets – Post-graduate, JSC «NICEVT»
Hardware chains of computers and computer systems, used for the processing of analog information, are the data acquisition systems based on the analog-to-digital converters (ADCs). These devices and sub-systems are widely-spread in areas such as radar, radio navigation, science laboratory equipment, medical electronic equipment, various devices of automatics. When testing quality and performance of these systems, there are special requirements that increase testing time and complicate the testing methods. Creation of the universal testing methodology is very desirable, but the problem is hypothetical because of the wide variety of possible operation modes of the testing systems. Hardware manufacturers are trying to create special automation testing methods, taking into account the specifics only manufactured class of equipment. Unified system for quality testing may be built according to the scheme, which includes:
sequencer of tests;
result processing and report subsystem.
It is impotent, than the testing object is considered not distanced in the proposed scheme, but as an integrated part of the overall system. On the basis of unified testing schemes it can be considered the histogram method of measurement of pulse response parameters of data acquisition systems. Values of conventional pulse response parameters are interpreted so as suggested in . The pulse response measuring Algorithm is described in . The advantage of this algorithm is simpleness. Minimal volume of operations requires high speed execution of the program, based onf this algorithm, which excludes manual labor and influence of the «human factor». Calculation accuracy depends on the size of the tested samples, that allows to obtain the result with a smaller error than traditional oscilloscopic methode, especially at a small number of samples on the pulse period. It is possible to conduct measurements even in the situation when the period of the test pulse to two and less samples. The proposed algorithm allows to distinguish between such parameters as the vertex slope and the glitch on the pulse automatically. Accuracy of duty time measuring is not time-limited by sampling period. Algorithm has been tested in compliance with the method described in .
Practical implementation of the pulse response test algorithm found application in the program PM_test.vi, the principle of which is presented in . Investigation of the efficiency of this program allows making the following conclusions:
The method test using the program PM_test.vi has shown that the proposed algorithm can be recommended to use in automated pulse response measuring systems of data acquisition systems.
Simple and minimal volume of performed operations offer high speed execution of the program based on this algorithm, which excludes manual labor and influence of the «human factor».
Calculation Accuracy depends on the size of the tested samples, that allows to obtain the result with a smaller error than oscilloscopic method. To achievement accuracy of 1% it is enough to accumulate not less than 100 test pulses.
Part of the histogram methods for the quality parameters measurement of data acquisition systems are described in . Provided in this paper method is the original and complements existing methods, expanding the range of tasks solved with the help of histograms. In future it is planned to integrate the algorithm of pulse response parameters measurement in the automated testing system AIKS developed by CJSC «INSYS». In this system, it is applied the measurement method of the channels phase mismatch based on the calculation of the power cross spectrum for multichannel data acquisition systems. To this method also may be applied the histogram analysis of the value of phase mismatch, with which you can find answers to following questions: what is the deviation of the phase mismatch depending on time, temperature and other parameters, is whether this deviation incidental or consequential nature.
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