Re: [Discuss-gnuradio] To implement WiMAX with GnuRadio or not?

[Alexander Chemeris]

On Sat, May 28, 2011 at 19:52, Marcus D. Leech <address@hidden> wrote:
>> Problem here is that FIFO's are not very well suited for real-time
>> operation, IIRC. Have you tried a shared memory and shared signals
>> across applications?
>>
> It depends on what you mean by "real time".  Certainly FIFO I/O will be
> slower than
>  intra-flowgraph ring buffers, but not so horribly sluggish and latency
> prone that they
>  can't be used for a large class of real-time applications.

I mean "Soft Real-Time":
http://en.wikipedia.org/wiki/Real-time_computing#Hard.2C_firm.2C_and_soft_real-time

So, I actually do care about two parameters:
1) "Real-timeness" - i.e. whether using of this primitive can
introduce unexpected delays into execution.
2) Latency and throughput - if "real-timeness" requirement is met,
then I want to know how well performance of the primitive is.

> I use them extensively in a radio astronomy application, and they don't seem
> to add any
>  noticable latency above the already-not-spectacular latency within Gnu
> Radio.

Is there information about what is the biggest latency-injector in GnuRadio?

>> Good idea. With only one problem - XML is a bit of overhead for
>> real-time application messaging :)
>
> Are you concerned about parsing overhead?  And what do you mean by "real
> time"??
>  Are you concerned about reacting to stimuli on microsecond timescales? In
> which case,
>  deep thought would certainly be required about the entire architecture, and
> not just
>  the protocol "syntax".

That's what I try to do right now - evaluate whether GnuRadio can
perform well enough in general :)

I probably spent too much time developing VoIP media processing where
you can hear every "non-realtimness" with your ears. But RF processing
should be no less real-time, imho.

-- 
Regards,
Alexander Chemeris.