The file lpf_pwr.txt contains data from a hardware simulation of the low-pass filter. The first column is the baseband frequency (in MHz) into the filter and the second column is the power output of the filter (relative to the input power, in dB). The data covers the entire passband of the filter, but since not all of this is available to the user (7935/8192 bins reported) a little bit of the range is discarded.
The simulation clearly shows the ~0.06dB Gibbs phenomenon ripple in the filter.
The data should very closely match the performance of the hardware. The plot below superimposes the filter data (red line) with values measured by integrating a noise source for a long time on real hardware (white line).