This is a tool for analysing sinusoidal patterns in various xDSL data. for use with both Linux and Windows - and thanks to b*cat for testing the Penguinista version
To start in windows : ButterworthFilters
To start under *nix : mono ButterworthFilters.exe
The button opens a file - and it's most important that the correct file type is used as that's determines how the data is loaded. Supported File Types are CSV (pure data), the next three all access different data from the hybrid repsonse in the Broadcom Diagnostic Tool and finally HLog which reads either QLN or HLog data as produced by DSLStats.
The filtering works by removing sinusoids with a higher (or Lower) frequency than the cutoff therefore allowing patterns to be seen.
A Highpass filter only allows rapid changes in value to be seen and removes underlying trends.
A Lowpass filter allows the underlying trends to be seen without any noise.
Starting at a value of 0 - this will give the original graph. As this is increased, for a low pass filter, the general trend of the line will appear followed by more detail as the cutoff is increased. It's slightly easier to think that the low pass will find things of a short length, and the high pass will find longer things.
HybridResponse_3 is a good example, using a file type of HybridResponse_Response:
A low pass with a cutoff of 0.04 will highlight a length of 97m (approximately where the line guage changes from 0.9mm to 0.5mm)
A high pass with a similar cutoff (~0.07) will highlight a length of ~900m (the low pass filter beyond the DLSAM is about 822m away). Although line noise will affect the high pass filter more and give false very long distances.
It's worth just having a play if you are interested - some test data is provided.
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