Re: [Discuss-gnuradio] Gettin data out from GRC to C++ or java?

[John Malsbury]

You could use XML-RPC, which is widely supported across many languages, to pull a buffer of data from a flowgraph.  See screenshot for an example.  I've include some data reduction just so the XML-RPC output in the python terminal is more illustrative [a large array would displace the import/connect instructions above the get_data() call).

 

This method falls apart when you try to sink anything at a rate higher than 500e3 into the vector.  malloc errors....   More ideally, you'd use a vector probe instead of a vector sink so you don't have to worry about resetting data periodically.  I just don't have the stock vector probe in my universe right now. 

Still, I think a finite acquisition is the way to go for your application.

-John


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On Fri, Oct 17, 2014 at 8:41 AM, John Malsbury <address@hidden> wrote:

Ernest - here's an example of how to connect other stuff to GNU Radio via pipes - granted at much lower sample rates.  Higher sample rates shouldn't effect the pipe, but Matlab may not keep up with a typical 802.11 sample rate.

http://youtu.be/GBmli8Vflig?t=2m33s

If you *could* get this 3k sample snapshot, how do you make sure a useful signal will be present?  

If you're doing processing in another framework, why don't you just use UHD directly w/out GNU Radio?  There are finite acquisition calls in UHD IIRC...

-John

On Fri, Oct 17, 2014 at 5:15 AM, Martin Braun <address@hidden> wrote:

On 10/17/2014 12:40 PM, Ernest Szczepaniak wrote:
> So i if would like to create a simple flow graph, with USRP source and file
> sink only, is there any way to control file buffer size (i.e i want that any
> file consist of 3k 32complex samples every write)?

You can't control how many samples the USRP source will produce per run.
And I'm not sure that's really what you want.

> Any 3.7 compatibile pipe pack? tried gr-pipe but typical "gnuradio-core"
> error :(

I was suggesting you create a named pipe instead of a regular file. If
you don't know what that means, I suggest looking it up, it's a basic
concept of most OSes, and Google will have all the info you need.

You don't need any addons for that.

M


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