DSO203 GCC APP - Community Edition (2.51+SmTech1.8+Fixes)

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Jerson
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by Jerson » Mon Mar 05, 2012 2:25 pm

Hi Pedro

I took the files from the Github latest release 1.12

Always comes back with ERR or NOT

Regards

pmos69
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by pmos69 » Mon Mar 05, 2012 2:28 pm

Jerson wrote:Hi Pedro

I took the files from the Github latest release 1.12

Always comes back with ERR or NOT

Regards
Try extracting from the zip (on the first post).
Github has the nasty habit of messing up binary files...
Image

Jerson
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by Jerson » Mon Mar 05, 2012 2:34 pm

Hi Pedro

Thank you very much. That did the trick. It works now. Surprising since I downloaded even the ZIP from Github

Thanks again

Regards
Jerson

pmos69
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by pmos69 » Mon Mar 05, 2012 2:36 pm

Jerson wrote:Hi Pedro

Thank you very much. That did the trick. It works now. Surprising since I downloaded even the ZIP from Github

Thanks again

Regards
Jerson
Yes, I think it's git that does some sort of conversion right when I upload things.
Would fix it, but my git knowledge is very limited :/
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Jerson
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by Jerson » Mon Mar 05, 2012 2:47 pm

First impressions. FFT seems to lose the ending frequency when going >= 5uS. I love the 2nd button press choosing the trigger levels. Very handy

Regards
Jerson

pmos69
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by pmos69 » Mon Mar 05, 2012 3:16 pm

Jerson wrote:First impressions. FFT seems to lose the ending frequency when going >= 5uS. I love the 2nd button press choosing the trigger levels. Very handy

Regards
Jerson
Yes, the FFT is a bit "crude", but I just wanted to get a working version running. The thing with the ending frequency seems like a question of datatype or datatype conversion, but I didn't really look into it.

I've also used the FFT with 1024 points instead of 256 and it runs without issues and is much more precise, but displaying that involves a bit more work, scaling the output to the display window (and I didn't do that.)

The trigger level presets is all Marco's work :)

PS: oh, and I think I fixed the github binary files corruption thing...
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pmos69
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by pmos69 » Mon Mar 05, 2012 6:29 pm

Code: Select all

v1.13

- Corrections in the FFT calculations
		(was making a mess, as usual)
Image

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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by glt » Tue Mar 06, 2012 2:34 am

Let me take this opportunity and give a big thanks to Pedro, Marco and others that have incrementally contributed to improving the s/w. I think this was the original intend of this product, and gracious individuals have taken upon themselves the task to deliver the s/w. BRAVO!

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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by paf » Tue Mar 06, 2012 5:22 am

Yes, Marco and then Pedro did a great job, thank you very much. And the work of Pedro allows each of us to compile the firmware using a free compiler.

The integration of FFT is very nice but I don't understand what it measures exactly. Look at the following example (230V mains with 10x probe):
IMAG000.jpg
Two things irritate me:
  • why so many harmonics? The mains should be a very good sine, I don't expect anything significant above 50Hz. Is this noise because of the limited resolution of the ADC? Or a "feature" of the FFT? Of because of the vertical logarithmic scale?
  • the rays in the spectrum are not really rays, they are rather blurred - is that a "feature" of the FFT too (e.g. because of the width of the bandpass filter?)
Patrick

pmos69
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Re: DSO Quad GCC port (2.51+SmTech1.8+Fixes)

Post by pmos69 » Tue Mar 06, 2012 7:11 am

I would say the calculations are incorrect...

...or not.
I wouldn't say an 8bit capture of a sine with about 30 samples per cycle like you show is a very good representation of a sine wave.
It's a very poor one actually, and it would be strange to not get a lot of harmonics.

If you increase the time resolution (samples per cycle) you'll start getting better results.

Image Image Image

...but please remember - this is a 256 samples FFT.
It's usefulness is limited.
Had some problems reverting back to the 1024 points FFT I had first implemented, and will probably not be trying to get it running any time soon.
If someone want's to have a go at it... (all the FFT related code in the source is delimited with "// FFT" comments, and is actually very few lines of code)
Image

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