OboeTester loopback latency test needs more low freq noise immunity

[philburk]

When I run the test on a GBus it has low confidence, 0.32, because of all the low frequency energy. So we should try a high-pass filter with a 100 Hz cutoff.

Also we should try not using a Peak Detector and then looking for the narrow spike in the correlation results. The spike may not be where the peak correlation is.