Re: [Discuss-gnuradio] HELP! - Problem with radio application deploy

[bob wole]

Thanks Tom and Marcus for taking time out and explaining things on the list.

--

Bob

 

> How do you determine the size of taps? How much of a difference does
> setting the transition width from 1MHz to 10MHz make?
>
Generally, the wider the transition width, the fewer taps.

You can use the "firdes" functions, which is what the low-pass filter
blocks call in gnuradio, then take their output into a variable and
   have another variable be len(filter).


>
> On Tue, Nov 19, 2013 at 6:40 PM, Marcus D. Leech <address@hidden
> <mailto:address@hidden>> wrote:
>
>         I really appreciate the detailed explanation. I tried running
>         gr_filter_design last night and it asked me to install SciPy,
>         which I did not feel like doing at that time. I will try using
>         1MHz for my band, which may help get rid of the real-time
>         running issue.
>
>         Again, I appreciate your help with this matter.
>
>     Let's say you get a filter that's, oh, I dunno, 100 taps long.
>     That filter has to process every sample, so, that's 5e7 X 100 taps, or
>       roughly 5e9 FLOP/second.  Just for that one filter.  And your
>     flow-graph is likely doing other things *and* it's having to get
>     samples
>       all the way through your network or USB stacks into the
>     application layer as well, call that 100 instructions/sample.  So,
>     that's
>       5e7 x 100 = 5e9 OPS/second just to get your samples into the
>     application.  You're going to burn-up the cycles on your CPU pretty
>       quickly at 50Msps, even for doing "trivial" things.
>
>
>
>
>
>     --
>     Marcus Leech
>     Principal Investigator
>     Shirleys Bay Radio Astronomy Consortium
>     http://www.sbrac.org