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On 05/08/2013 04:33 PM, LD Zhang wrote:
Sorry for the
confusion. I have been using USRP in a rather micky-mouse
way. For the longest time, I was just capturing data on host
computer disk and do brute force processing in MATLAB. It’s
time for me to think about speed up. And the first thing is
to consider the USRP processing capability. The PLL may
still be the right solution if the PLL faithfully replicates
the original signal, which I think it should. But having the
gnu-radio doing the PLL, I am not sure there is much of a
speed gain. Maybe there are intelligent ways of organizing
this so that it can be sped up? Maybe the Gnuradio is faster
than Matlab. But these days the matlab has been awful fast,
not much slower than C. Still my matlab is not organized as
nicely as the gnuradio. Right now I don’t have any
streamlined processing. The suggestion on using the PFB
filterbanks and PLLs in parallel and streaming operation may
have significant speed up? Your opinion is appreciated.
I can't tell you if your application will run in real-time, but the
polyphase filterbank is the most CPU-efficient way to extract
multiple (usually, more than four) signals from a sample stream in
Gnuradio. You will probably find Gnuradio much faster than offline
processing in Matlab.
If the relative phase offset of multiple carriers is important, then
you really only want to run a single PLL on one of the carriers, and
use the frequency estimate to apply to all the carriers -- i.e., the
entire bank of signals -- so that phase is preserved relative to the
"reference" carrier.
--n
LD
From:
Marcus D. Leech [mailto:address@hidden]
Sent: Wednesday, May 08, 2013 4:03 PM
To: LD Zhang; address@hidden
Subject: Re: [Discuss-gnuradio] How many
multiple/simultaneous PLLs can I have running on USRP2?
Or am I wrong
that the resource is in the computer and not in the USRP?
LD
It's all in the computer,
unless you do an FPGA-based implementation. Gnu Radio
blocks run on the host machine, not the USRP hardware.
I admit to being a little bit surprised that you don't know
that already, given how long you've been posting things to
this list,
and using USRP hardware.
--
Marcus Leech
Principal Investigator
Shirleys Bay Radio Astronomy Consortium
http://www.sbrac.org
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