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a question about calculating the Rho

Question asked by roman on May 26, 2007
Latest reply on May 30, 2007 by hopcraft
I simulated the measurement that calculated the waveform quanlity of the random signal, and have some problems about the value of the waveform quanlity.

I refered to the article "Overview of code-domain power, timing, and phase measurements" from the Hewlett-Packard Journal, and simulated the processing of calculating the waveform quanlity under the environment of the matlab software.

First, i generated the random signal through interpolating and filting, and the signal is 1.6 MHz bandwidth, 2.56 MHz sampling rate, and produced the reference data by took a section of the random signal. Then, i calculated the Rho by the reference data and the randsom signal, and got the ideal value that equal to 1 at a synchronous point.

Second, i interpolated the random signal by 2 factor, afterward, i decimated the signal that been interpolated by 2 factor, so the sampling rate of the final signal was equal to the reference. I calculated the Rho by the same method with the first step, and the value is much less than 1.

Third, i interpolated the orignal random signal, and calculated the Rho by reference data, and find the more larger multiples of the interpolation, the more closed to 1.

Why did i get the much less than 1 at the second step, and the influence of interpolation?