Re: [Discuss-gnuradio] A question on gnuradio capacity of handling real time data streaming and signal processing with USRP N210 + gnuradio on host linux computer

[LD Zhang]

I am still learning from on line examples on how to do this in the gnuradio flow graph for testing out the ideas.

 

There seems to be two kinds of approaches to deal with the potential problem of data stream processing choke up:

 

1. Use a filterbank with many outputs. But for each output use a digital downconversion (DDC) block so that the data rates can go way down. Do say 5 streams at a time. Use throttle, or delay (if there is any), or skip head block to delay the processing the rest of the streams (besides the 5).

2. Still use the same filterbank but with no DDC. Phase lock on the first 5 carriers and delay/throttle/skip the rest. When done with the first 5, record the phase and terminate execution. Then move on the rest, so on and so forth.

 

I would like to check if these ideas sound correct. Also since I am a beginner in GRC, I am curious to hear for a seasoned developer which of the two above looks easier to do.

 

Thanks,

 

LD

 

From: address@hidden [mailto:address@hidden On Behalf Of Marcus D. Leech
Sent: Monday, May 13, 2013 4:46 PM
To: address@hidden
Subject: Re: [Discuss-gnuradio] A question on gnuradio capacity of handling real time data streaming and signal processing with USRP N210 + gnuradio on host linux computer

 

Dear Group,

 

I have a need to do real time or near real time tracking (most likely phase-lock loop) of multiple narrow-band carriers/tones in a 1MHz band of signal input using USRP N210 and gnuradio running on a reasonable linux host. Say the carriers/tones are embedded in the band from -500 kHz to +500 kHz. If I want to lock on to 20 carriers in that band using gnuradio PLLs, will this choke up the computer? If there is a problem, I also would like to think how to reduce data rates. But I don’t know whether multiple LO’s are an option.

 

Thanks for reading,

 

LD

The best thing to do is to put together a simulation, and see if your computer is up to the task or not.

Something that we don't have a really good handle on in Gnu Radio is some  estimates for the computational complexity of
  individual blocks in a flow graph.

If we did, one could do some simple arithmetic:

add up all the complexities of all the blocks on your "fast path" (by this I mean blocks that must necessarily operate at the input sample rate)
multiply that by the sample rate

That gives you an idea of the numbers of MFLOPS/GFLOPS required to support your application.

-- 

Marcus Leech

Principal Investigator

Shirleys Bay Radio Astronomy Consortium

http://www.sbrac.org