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Author Topic: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters  (Read 1118 times)

boozy

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Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« on: August 15, 2018, 10:54:48 PM »

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.

« Last Edit: August 16, 2018, 10:25:10 PM by boozy »
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boozy

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Re: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« Reply #1 on: August 15, 2018, 10:58:18 PM »

Placeholder for File Format documentation

CSV - simply a list of values separated by commas.  May have multiple lines.

HybridResponse_Response - this will ignore the first line in the file and then read space separated values to an empty line or the end of the file.  Also reads other files produced by the Broadcom Diagnostics tool e.g. QLN
HybridResponse_Impulse - finds the impulse section of the Hybrid response output and then reads the space separated values
HybridResponse_Phasese - as above but for the phasese section of the file

HLog - reads the file until it finds a line starting with "Tone" and then reads the subsequent values (ignoring the tone).  Values less than or equal to -96 will be averaged out to the previous and next values.  This can be messy dependent on how the Hlog for your line looks.

For anything else I would recommend using the CSV format and creating the file yourself.
« Last Edit: August 16, 2018, 10:31:41 PM by boozy »
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Weaver

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Re: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« Reply #2 on: August 15, 2018, 11:56:08 PM »

So nice to see CLR (is it? .Net?) being used on *nix with Mono!
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boozy

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Re: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« Reply #3 on: August 16, 2018, 10:37:20 PM »

It's .Net CLR (C#) - although I have to admit I've never put a UI on one before for Mono.  The first component I used for graphing didn't work on Mono, so must have went to native code at some point and the current MonoDev wouldn't build from git... or I didn't have the patience to build it (was only one bad project reference, so likely a bad check-in as the compiled version was present).  So took a few tries to get it working.
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roseway

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Re: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« Reply #4 on: August 19, 2018, 10:21:50 AM »

I've had a play with this, although I confess that it's way over my head. It all seems to work on my Debian system, although running it did throw up one error message:

Quote
Gtk-Message: 10:13:54.881: Failed to load module "atk-bridge"

I've checked, and I do have libatk-bridge v2.22.0 installed.
« Last Edit: August 19, 2018, 10:25:06 AM by roseway »
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  Eric

boozy

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Re: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« Reply #5 on: August 20, 2018, 08:27:46 PM »

That error seems to crop up occasionally in Mono and I don't see any solutions to it (or at least any well documented ones).  It's way below the level of my code, so I'm not sure there's anything I can do about it.  At least it still works.
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roseway

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Re: Analysing HLog/QLN/Hybrid Reponses using Butterworth Filters
« Reply #6 on: August 20, 2018, 10:35:29 PM »

Yes, I thought that might be the case.
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  Eric