The use of SPW Interpolate Blocks

 As mentioned previously, the simulation utilised SPW interpolate blocks in order to generate of the correct noise bandwidth and sampling frequency. It was necessary to ensure that such a process resulted in a signal that had a sampling frequency of 30Hz but produced a TDEV that was equivalent to that of a 5Hz bandwidth white gaussian noise source. The effect of 5Hz low pass filtering white gaussian noise with a noise bandwidth of 15Hz was also considered. The results of this are shown in figure 8.24 and demonstrate that the use of SPW interpolate blocks is acceptable. figure 8.24.

 

Figure 8.24:   TDEV plot verifying appropriate behaviour of interpolated 5Hz bandwidth WGN

It can be seen from the top plots that the 5Hz bandwidth interpolated white gaussian noise noise produces a nearly identical TDEV plot to the same signal un-interpolated in the observation intervals of interest ($\geq 0.1s$). The bottom plots show 15Hz white gaussian noise and that low pass filtering does not satisfactorily produce the equivalent of 5Hz noise. The top plots also confirm the desired independence of TDEV on the size of the data set since the interpolated source has 3 times the number of points of the un-interpolated one but produces a near identical TDEV.