Hi Franco, I sent you an invite to join slack casper-astro.slack.com. I hope it works. Let me know.
Kind regards, Adam Isaacson South African Radio Astronomy Observatory (SARAO) Hardware Manager Cell: (+27) 825639602 Tel: (+27) 215067300 email: [email protected] On Mon, Dec 30, 2019 at 8:30 PM Franco <[email protected]> wrote: > Hi Dan, > > I was unaware that the compiler was able to remove unused logic, that's > pretty useful. > What I need is one real input to one complex output, so I'll check Nitish > model and import it to ROACH2 if I need to, thanks for the info. > > On a sidenote: It is possible still to join the slack? I remember > something was mentioned about sending an email earlier this year. > > Thanks, > > Franco > > On Mon, Dec 30, 2019 at 3:10 PM Dan Werthimer <[email protected]> > wrote: > >> >> hi franco, >> >> are you looking for an FFT with a real input and complex output? >> >> you mentioned you are connected the unused inputs of the the >> biplex_real-4x to ground. >> this is useful, as the compiler should remove all the unused parts of the >> FFT, >> although it's probably not as resource efficient as a dedicated single >> input real to complex FFT. >> >> if you need further reduction in resources, >> nitish recently developed a single stream complex to complex fft. >> nitish's posting on casper's snap slack channel is appended below . >> >> you could modify nitish's design to compute two reals in one complex >> FFT, >> or a single real of N points in an N/2 complex FFT. >> >> best wishes, >> >> dan >> >> ------------------------------ >> new messages >> Nitish <https://app.slack.com/team/UMWDNQD7W> 10:54 PM >> <https://casper-astro.slack.com/archives/CMNK6V19Q/p1576911266004700> >> Hi, in reference to our previous discussion concerning the complex FFT of >> a single stream of samples, we wanted to share the piece of the design >> which worked, might prove useful to someone. So, we clock the SNAP at 250 >> MHz and ADC is done at 250 MSps, thus one sample per clock cycle. We wished >> to perform complex FFT, which would require a block taking 1 stream at 1 >> sample per clock. The blocks available could only take powers of 2 samples >> in parallel from a given stream, thus we had to find another way. Thanks to >> Jack Hickish, we managed to make a small design with the FFT internal >> blocks which performs the job. Please find attached. Channels 1 and 2 are >> two separate streams (two distinct signals) coming from the mixer and they >> contain 1 complex sample per clock cycle. The example shows a 2048 points >> FFT. The unscrambler block is needed to put some order in the frequency >> channels output. The channels from any one output have to be put in order >> using this small code for example: >> >> for i in range(0, 1024): >> spectrum1.append(channels1[i]) >> spectrum1.append(channels1[2047 - i]) >> >> (edited) >> Single_stream_complex_FFT.jpg >> [image: Single_stream_complex_FFT.jpg] >> >> <https://files.slack.com/files-pri/THU1J9JDC-FRYDQAY5S/single_stream_complex_fft.jpg> >> >> >> >> >> >> On Mon, Dec 30, 2019 at 9:31 AM Franco <[email protected]> wrote: >> >>> Hello everyone, >>> >>> Is there an FFT block in the CASPER library (ROACH2) that can be used as >>> 1 input -> 1 output? The closest thing I've found is the 'fft' block which >>> has a minimum of 2 inputs. >>> >>> For now I'm using the fft_biplex_real-4x and zeroing 3 of the 4 inputs, >>> but that's wasteful. I've also tried the Xilinx FFT block, but it has a >>> strange problem where the noise floor increase considerably when injecting >>> a tone at the middle point between two FFT bins. >>> >>> Thanks, >>> >>> Franco Curotto >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "[email protected]" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion on the web visit >>> https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CACBfcEnPcxk-k4oFTD__%2BVYkTsGTSc%2B85uiLqejdEUthdGXwLA%40mail.gmail.com >>> <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CACBfcEnPcxk-k4oFTD__%2BVYkTsGTSc%2B85uiLqejdEUthdGXwLA%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> You received this message because you are subscribed to the Google Groups >> "[email protected]" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vFeEcLgYhcYLfL8KuYM4%3DzcDkmk4yC%2BgWWqc%2BttDi40pA%40mail.gmail.com >> <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CAGHS_vFeEcLgYhcYLfL8KuYM4%3DzcDkmk4yC%2BgWWqc%2BttDi40pA%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups " > [email protected]" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CACBfcEn1O-RhKbRhpo2XDDgWhSpshQUadpMkq3KZ%3Dnstsgzwtw%40mail.gmail.com > <https://groups.google.com/a/lists.berkeley.edu/d/msgid/casper/CACBfcEn1O-RhKbRhpo2XDDgWhSpshQUadpMkq3KZ%3Dnstsgzwtw%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "[email protected]" group. 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