Re: [Discuss-gnuradio] GSoC: Filter design enhancements progress

[Tom Rondeau]

On Tue, Jun 26, 2012 at 1:50 PM, sreeraj r <address@hidden> wrote:
> Hi John,
> As Marcus already mentioned you can use design functions from firdes module
> (gr_filter_design also uses these modules).
>
> Martin, Josh and Tom gave me many suggestions regarding adding the designer
> to GRC, so that users can launch the designer from GRC itself (something
> like this http://www.youtube.com/watch?v=aqLIPHXCM1M&feature=plcp). This
> feature will be added to GRC once the design tool is complete.
>
> Thank you for your suggestions.
>
> ---
> Regards
> Sreeraj Rajendran
> http://home.iitb.ac.in/~rsreeraj
>
> ________________________________
> From: John Malsbury <address@hidden>
> To: address@hidden
> Sent: Tuesday, 26 June 2012 10:51 PM
> Subject: Re: [Discuss-gnuradio] GSoC: Filter design enhancements progress
>
> That is pretty awesome, Sreeraj.  Is the output of the program a set of
> co-efficients to be copy-pasted, a compilable block, or something else?  It
> might be useful to have a feature where the user can call a custom python
> script with the co-efficients passed as arguments.  This would allow users
> to easily generate formatted files, like those used by Xilinx coregen or
> some custom format that might be poked to the FPGA, for example.  It would
> be neat to make some updates to GRC to allow the user to open the utility
> and re-generate co-efficients as they do in MATLAB.
>
> This is making me think of some other potential projects, like a similar
> 'digital modulation designer'.  For example, we might use a single block for
> all modulation types, select the modulation type and parameters, run
> simulations to determine BER vs. Eb/N0, theoretical discrete constellations,
> ACPR, PAR, etc.  Or perhaps, a "packet designer" where you can graphically
> configure FEC, interleaving, sync words, etc.  Obviously, the complexity on
> this one could grow real fast.
>
> Just ideas... Hopefully you'll have a chance to present your approach to
> this at the GNU Radio conference.
>
> -John


Yeah, I agree with John, it would be nice to be able to get the taps
from the filter design tool into a Python program easily. As Sreeraj
said, this tool uses firdes and optfir from GNU Radio, so you could
just transfer the numbers from one to the other once you're satisfied
with your filter design, but that seems inefficient.

Before handing this off to Sreeraj for the GSoC, I had implemented a
"save as" feature in the tool that saves the coefficients to a CSV
file, so you could, like to said, John, read in these taps. There's no
helper for it, yet, though, so you have to open and read the CSV file
from the basics, but it could easily be rolled into a single function.

On the other hand, since the gr_filter_design tool is PyQT based, we
could create a set of signals and slots to be able to change things
programmatically. With a "get_taps" function, we could have this
program be launched as a dialog box, create the taps, and then
directly import them all from a single Python GNU Radio app. You
wouldn't want to do this all the time, but it could be a nice feature
(for instance, you first check if there is a CSV file of taps, and if
not, launch the design tool to create them and save them for the next
time).

Tom