data acquisition systems
base shift (zero shift)
An integral hardware node of data acquisition systems in a computer are analog-to-digital converters (ADC). Among the dynamic parameters of the ADC can be identified pulse parameters which often have priority. These parameters characterize the possible distortions of the signal presentation form at the ADC output under the influence at the input of the rapidly changing signal. One of the possible ways of the pulse response measuring is the application of the method of the statistical data processing.
To confirm the efficiency of the proposed method it is necessary to perform analytical testing with the help of the mathematical model of the signal, parameters of which are known in advance. For analytical test was created the program PM_test.vi in the environment of LabVIEW. The mathematical model of the test signal describes the periodic signal with a rectangular shape with a known value of distortion characteristics. The model is based on the principle - top, base, falling and rising fronts of the pulse are approximated by straight lines, and the transition process at the front is a decaying exponentially harmonic oscillation. The signal, which is formed in this way, can include 6 types of simple distortion or 64 their combinations with different variations of parameters. After a series of tests, the average error of the duty cycle is 3.4% and a maximum is 11.6%. This is a valid result of measurement of this parameter.