> On 2004-08-07 19:34:32 +0200, Jerry Avins <jya@ieee.org> said:
>
>>>> "dfr16RFFT" and "dfr16IFFT". ... "dfr16RIFFT" ...
>>
>>
>> I didn't see existing differences. (Believe me: I looked long and hard.)
>> Later, I found them, but I didn't delete my message in time. Chalk it up
>> to old age if you like, but in reality, I seem to be somewhat dyslexic.
>>
>> Jerry
>
>
> Hi Jerry,
>
> I don't think that your sight or language skills are in question here.
>
> In my opinion, whoever is responsible at Motorola for naming the FFT
> routines thusly should be hanged with his balls on a tree (direct
> translation of the German saying "Er geh�rt an den Eiern aufgeh�ngt").
>
> It's almost as bad as using underscores in function names... ;-)
It probably seebed like a good odea at the time. There's no use nor
agitating over what might have been. "Wenn meine Bubbe Eier hatte ..."
(For those at home: "If by grandmother had balls, she would have been my
grandfather.")
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Stephan M. Bernsee●August 8, 20042004-08-08
On 2004-08-07 19:34:32 +0200, Jerry Avins <jya@ieee.org> said:
>>> "dfr16RFFT" and "dfr16IFFT". ... "dfr16RIFFT" ...
>
> I didn't see existing differences. (Believe me: I looked long and hard.)
> Later, I found them, but I didn't delete my message in time. Chalk it up
> to old age if you like, but in reality, I seem to be somewhat dyslexic.
>
> Jerry
Hi Jerry,
I don't think that your sight or language skills are in question here.
In my opinion, whoever is responsible at Motorola for naming the FFT
routines thusly should be hanged with his balls on a tree (direct
translation of the German saying "Er geh�rt an den Eiern aufgeh�ngt").
It's almost as bad as using underscores in function names... ;-)
--
Stephan M. Bernsee
http://www.dspdimension.com
Reply by Jerry Avins●August 7, 20042004-08-07
Stephan M. Bernsee wrote:
> Jerry Avins <jya@ieee.org> wrote in message news:<4113de94$0$5907$61fed72c@news.rcn.com>...
>
>>Stephan M. Bernsee wrote:
>>
>>
>>>"dfr16RFFT" and "dfr16IFFT". ... "dfr16RIFFT" ...
>>
>>??
>>
>>Jerry
>
>
> Hi Jerry,
>
> what's the part you don't understand?
>
> --smb
I didn't see existing differences. (Believe me: I looked long and hard.)
Later, I found them, but I didn't delete my message in time. Chalk it up
to old age if you like, but in reality, I seem to be somewhat dyslexic.
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Stephan M. Bernsee●August 7, 20042004-08-07
Jerry Avins <jya@ieee.org> wrote in message news:<4113de94$0$5907$61fed72c@news.rcn.com>...
> Stephan M. Bernsee wrote:
>
> > "dfr16RFFT" and "dfr16IFFT". ... "dfr16RIFFT" ...
>
> ??
>
> Jerry
Hi Jerry,
what's the part you don't understand?
--smb
Reply by Shafik●August 6, 20042004-08-06
"Ryan Mitchley" <rmitchle@removethis.worldonline.co.za> wrote in message news:<41137145$0$5465$812600b3@news.nntpaccess.com>...
> Check that your data is aligned to power-of-2 boundaries appropriate to the
> FFT size.
>
> This has caught me more times than I would like to admit.
>
> Ryan
I am in fact using the proper functions for the "real" fft: dfr16rfft
and dfr16rifft.
What exactly do you mean by "data alignment". Do you mean memory
boundary alignment or just the size? Because I am using a 16 size
input data array.
Thanks
--Shafik
Reply by Jerry Avins●August 6, 20042004-08-06
Stephan M. Bernsee wrote:
> "dfr16RFFT" and "dfr16IFFT". ... "dfr16RIFFT" ...
??
Jerry
--
Engineering is the art of making what you want from things you can get.
�����������������������������������������������������������������������
Reply by Stephan M. Bernsee●August 6, 20042004-08-06
On 2004-08-06 19:46:39 +0200, shafik@u.arizona.edu (Shafik) said:
> I am actually using Motorola's built in "Real" FFT and "Real" inverse
> FFT. Even with just observing the output of the FFT stage, I get
> strange results for a simple sine wave (I would expect a single
> spike). I have no control over the implementation of the algorithm
> itself, but I would hope that Motorola doesnt have such a serious bug
> in their 5th version of the SDK.
>
> What's going on?
> --Shafik
You were saying in your original post that you are using the routines
"dfr16RFFT" and "dfr16IFFT". The latter is *not* the inverse real
transform, the inverse real transform is "dfr16RIFFT". Either you
mistyped this in your original message or in your code...
--
Stephan M. Bernsee
http://www.dspdimension.com
Reply by Shafik●August 6, 20042004-08-06
Stephan M. Bernsee <spam@dspdimension.com> wrote in message news:<2ngnvrFmiluU1@uni-berlin.de>...
> Shafik,
>
> as I read your post, you're using a "Real" FFT for the forward
> transform stage and a complex-output version for the inverse. That
> won't work. Try using the real-output inverse transform (dfr16RIFFT)
> and make sure it takes care of the necessary scaling (most probably
> that is already included), then you should get what you expect.
I am actually using Motorola's built in "Real" FFT and "Real" inverse
FFT. Even with just observing the output of the FFT stage, I get
strange results for a simple sine wave (I would expect a single
spike). I have no control over the implementation of the algorithm
itself, but I would hope that Motorola doesnt have such a serious bug
in their 5th version of the SDK.
What's going on?
--Shafik
Reply by Ryan Mitchley●August 6, 20042004-08-06
Check that your data is aligned to power-of-2 boundaries appropriate to the
FFT size.
This has caught me more times than I would like to admit.
Ryan
Reply by Stephan M. Bernsee●August 6, 20042004-08-06
Shafik,
as I read your post, you're using a "Real" FFT for the forward
transform stage and a complex-output version for the inverse. That
won't work. Try using the real-output inverse transform (dfr16RIFFT)
and make sure it takes care of the necessary scaling (most probably
that is already included), then you should get what you expect.
--
Stephan M. Bernsee
http://www.dspdimension.com