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Re: [Discuss-gnuradio] Newbie wonders about latency
From: |
Matt Ettus |
Subject: |
Re: [Discuss-gnuradio] Newbie wonders about latency |
Date: |
Tue, 28 Dec 2004 15:32:01 -0800 |
User-agent: |
Internet Messaging Program (IMP) 4.0-cvs |
Quoting John Sidles <address@hidden>:
> Dear GnuRadio folks
>
> We at the University of Washington are quite interested
> to apply the Gnu Universal Software Radio Peripheral (USRP)
> as a nanomechanical device controller:
>
> http://www.gnu.org/software/gnuradio/doc/exploring-gnuradio.html#usrp
>
> Basically, our task is to observe the complex amplitude
> of a MHz-carrier nanomechanical oscillator, then apply a
> controlling force that damps thermal oscillations.
Very interesting application!
> For this to work, the phase lag of the USRP processing
> chain
>
>
> analog in ->
> Rx daughterboard ->
> linear filter ->
> Tx daughterboard ->
> analog out
>
>
> should be no more than about 100 microseconds.
> Is this kind of latency achievable?
Since you don't have a round-trip over the USB bus, there isn't much latency at
all.
I don't know how complex your "linear filter" is, but the rest of the stuff
should have a latency of significantly less than 1us. More like in the 20-50
ns range.
The FPGA itself can be clocked at 128 MHz (or even 192MHz for small
computations), so that is what you should use to figure out the filtering
speed.
> Any advice you folks can give us would be *very* welcome.
>
> Sincerely
> John Sidles
> http://courses.washington.edu/goodall/MRFM/
Thanks for your interest,
Matt