FFT for Quad?

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G7psz
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FFT for Quad?

Post by G7psz » Thu Jun 16, 2011 1:19 am

Is there any interest in a Specrtum analysis function on the Quad? There was a thread about this for the DSO Nano, but this seems to have dried up now.

A full screen spectrum analysis display extending to 20mhz (should be possible with 72mhz sampling) would be impressive, but the processor might not have the capacity and the dynamic range would be limited to 40db by the 8 bit sampling limitation.

I must confess my development skills for this project are zero, but I could certainly use the results of such an effort.

G7PSZ

tgo
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Re: FFT for Quad?

Post by tgo » Thu Jun 16, 2011 2:06 am

Is it possible? Sure, there's an FPGA there so the integer discrete cosine transform is completely feasible.

What would it take to implement it? Please throw your weight behind this: DSO Quad source code. The more people who ask for it, the more likely this project will be open sourced. It's not as of right now.

Without the source code, there's no way to make this kind of dramatic change to the device.

With the source code, we could even tell those who think there are major bugs to get in and help fix them. Or go recruit someone to fix it. As it is, only two guys can really move this project forward. (In case you can't tell, I think that's a tragedy.)

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Re: FFT for Quad?

Post by gabonator1 » Thu Sep 15, 2011 8:34 pm

It is possible, I don't know whether there is enough space on the FPGA for the FFT algorithm, but the transformation can be done on the processor without any problem:

Here is a simple application (keep holding the fourth button to start it)
http://valky.eu/data/hardware/ds203_ffthex.zip
First button switches display mode
Second button starts and stops scanning

http://www.seeedstudio.com/forum/viewto ... =22&t=2352

paf
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Re: FFT for Quad?

Post by paf » Thu Jan 12, 2012 12:55 am

Hello

Nice application, thank you!

Three questions:

1) when installing the application (on marcosin's sys25116), the USB disk does not disconnect automatically and I get a timeout error on the PC - but after that the application is installed anyways and seems to work. Incompatible systemversion?

2) are there any further developments to this application (like a nicer GUI)?

3) is it possible to install it as 2nd or 3rd application (as 4th application I already have a frequency response analyser)? I have no chance of recompling it, as I haven't compiled anything for 20 years now...

Thanks
Patrick

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Re: FFT for Quad?

Post by kb1gtt » Sun Jan 22, 2012 9:37 pm

I got a spread sheet FFT working. I saved as .csv from the DSO, then copied the data into another spread sheet, and got FFT graph. I found this xls as a starting point. http://gozips.uakron.edu/~dorfi/fft256.xls which I modified to be specific for the DSO QUAD data and posted that modified version of it at this link. http://daecu.googlecode.com/svn/misc/DS ... t_4095.xls

See attached picture as a snap shot of the results.

[edit]Updated broken link above.[/edit]
Last edited by kb1gtt on Fri Apr 12, 2013 6:49 am, edited 1 time in total.

stuartfreynolds
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Re: FFT for Quad?

Post by stuartfreynolds » Wed Apr 10, 2013 5:17 am

That spreadsheet looks really handy right now. I cannot open the modified spreadsheet with the link though. Is it still available anywhere?

kb1gtt
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Re: FFT for Quad?

Post by kb1gtt » Fri Apr 12, 2013 6:54 am

I just updated the link. The link broke when a moderator (Mark aka mk_e) over in the open5xxxecu stuff decided to be malicious and mangled the stuff I had posted. So I moved to a repo where I'm the admin, such that I can avoid such issues. The link that is now posted should work. I hope you find it useful.

Also it might be worth noting, the community firmware of the QUAD now includes the FFT, which is what I now use as opposed to the xls dumps.

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tamuccuser
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Re: FFT for Quad?

Post by tamuccuser » Fri Jun 14, 2019 9:09 pm

The link with the modified data is not working. Where else can I find it? I know it's quite an old thread, but I'm looking for the valid FFT graph.

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