Constant Q transform spectrum analyzer

Andrey Demenev

I have been asked many times about this piece of code. And today I have got a comment at my Youtube page saying I am cheating about this. Here is the code and schematic. I do not have time to prepare English language documentation. Anyone who is really interested, and equipped with theoretical knowledge about constant-Q transform, can get how this all works. The simplest way to get this working is to use VGA output - although the code supports many other display types. Schematic and board layout in Eagle CAD format are included. The firmware should be compiled with BSTC. You can get the idea about options to use from the code and build_all script

Judith_B.zip

Andrey Demenev

Here is a spectrum analyzer made by someone else, using my board and firmware

Mike Green

Lovely workmanship.

Publison

Mike Green wrote: »

Lovely workmanship.

+1

richaj45

Andrew, so what is your algorithm?

Were can i get a tech look at the board of yours?

How many props does it use.

Does it use biquad digital filters?

What AD do you use?

What kind of tubes are those being driven?

Beautiful workmanship!!

Rich

Phil Pilgrim (PhiPi)

Andrey,

Very, very nice! For those interested, here's a paper that talks about constant Q transforms:

http://www.imamu.edu.sa/Scientific_selections/abstracts/Math/Calculation%20of%20a%20constant%20Q%20spectral%20transform.pdf

-Phil

Rayman

Very cool and interesting stuff...

You could have a Propeller do something when you whistle a tune, like in that James Bond movie...

Toby Seckshund

There was an article, about a year back I believe, in Elektor, that used neon tubes like that for VU meters on a Valve amplifier. They said that they had to come from Russia.

It is good to see some of the old technology still being made, and used in this case so beautifully used.

Alan

Phil Pilgrim (PhiPi)

The same effect can be obtained with the EL tubes that Parallax sells -- or used to sell, viz:

http://forums.parallax.com/showthread.php/117022-Electroluminescent-wire-something-you-would-buy-from-Parallax?p=851938&viewfull=1#post851938

-Phil

Andrey Demenev

richaj45 wrote: »

Andrew, so what is your algorithm?
Were can i get a tech look at the board of yours?
How many props does it use.
Does it use biquad digital filters?
What AD do you use?

The answers can be found by looking inside the archive attached to the first post

richaj45 wrote: »

What kind of tubes are those being driven?

IN-13. Sellers from Russia and Ukraine have lots of them on Ebay,


The spectrum analyzer was named after Professor Judith C. Brown from MIT. She published some papers on signal analysis, and about CQT in particular.