On Fri, 4 Feb 2022 at 07:08, Morag Brown wrote:
> Hey Nikhail,
>
> The FFT is a Hermitian function, which means that it has the property:
>
> [image: Screenshot from 2022-02-04 08-34-24.png]
>
> This principle is used in the real wideband FFT to compute 2 real FFTs
> using one complex FFT core -
On Fri, 4 Feb 2022 at 10:41, Jack Hickish wrote:
>
>
> On Fri, 4 Feb 2022 at 07:08, Morag Brown wrote:
>
>> Hey Nikhail,
>>
>> The FFT is a Hermitian function, which means that it has the property:
>>
>> [image: Screenshot from 2022-02-04 08-34-24.png]
>>
>> This principle is used in the real wi
Hi Morag and Jack,
Thank you for the prompt response. It was great to learn about the
Hermitian trick to combine 2 real FFTs - that's very interesting.
So, unless I am wrong, perfect reconstruction / inversion is not possible
because the information in the Nyquist bin is thrown away? (I hope I am
On Fri, 4 Feb 2022 at 15:04, Nikhil Mahajan
wrote:
> Hi Morag and Jack,
>
> Thank you for the prompt response. It was great to learn about the
> Hermitian trick to combine 2 real FFTs - that's very interesting.
>
> So, unless I am wrong, perfect reconstruction / inversion is not possible
> becaus
On Fri, Feb 4, 2022 at 10:10 AM Jack Hickish wrote:
>
>
> On Fri, 4 Feb 2022 at 15:04, Nikhil Mahajan
> wrote:
>
>> Hi Morag and Jack,
>>
>> Thank you for the prompt response. It was great to learn about the
>> Hermitian trick to combine 2 real FFTs - that's very interesting.
>>
>> So, unless I
Hi Nikhil,
>> perfect reconstruction / inversion is not possible because the information
>> in the Nyquist bin is thrown away?
Correct, but imperfect reconstruction should work.
A real-valued signal has a Hermitian spectrum, and an FFT has a cyclic
response. That results in two things;
*
Hi Dave,
That sounds like the best solution here. In my case, I am lucky that the
analog bandpass is a lot smaller than the overall bandwidth - so the
Nyquist bin contained mostly noise and assuming it is zero shouldn't hurt
reconstruction efforts too much.
> If you want to Google the terminology
Hi Nikhil,
>> I find DSP terminology confusingly named for newcomers
I think engineers do this on purpose …
Several good books:
Classic text (this is where a PFB is called a Weighted Over-Lap Add = WOLA)
Multi-rate Digital Signal Processing, Crochiere and Rabiner, 1983 (you can find
PDFs of th
Hi Nikhil,
What you want to look for is non-critically-sampled PFBs and their inverses.
Unfortunately they go by many names, such as PFBs, analysis/synthesis filter
banks, WOLA filters, Channelizers, FFT Filter Banks, etc.
The issues that Jon and Matt raised are specific to critically-sampled
Hi Jon,
This would be great to have if you are willing to share the draft. I am
fairly certain the PFB used in PUPPI is also critically-sampled and so this
work would be applicable.
Cheers,
Nikhil
On Fri, 4 Feb 2022 at 11:54, Jonathan Le Roy Sievers, Prof <
jonathan.siev...@mcgill.ca> wrote:
>
Hi Nikhil,
The type of PFB used in the casper library falls in the category of uniform
critically sampled PFBs. Uniform because all the filters in the PFB (you
can think of a PFB as passing your signal through a set of narrow filters
at different frequencies) are derived from the same prototype lo
Thanks Kaj,
Good luck. Our Alveo tool flow will use Ubuntu 18.04.5 LTS and Matlab
R2021a for now.
Kind regards,
Adam
On Thu, 03 Feb 2022, 12:34 PM Kaj Wiik, wrote:
> Hi Adam,
>
> Yes, indeed wheel stuff does not seem to affect anything. I made a pull
> request
> and it was merged.
>
> I am cu
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