Re: [Discuss-gnuradio] Test-bed application: how to control GUI app and gr_vector_source

[Tom Rondeau]

On Wed, Nov 10, 2010 at 12:52 PM, Andis Dembovskis
<address@hidden> wrote:
> Hello, dear GNU-Radio community,
> Some last weeks I am coping with how to run and reconfigure gr.top_block on
> the fly, didn't manage, so I thought, maybe someone out there could give me
> some hint.
>
> I am writing an application which is expected to send different test signal
> through USRP2 - to test some other embedded receivers. So I need to
> reconfigure top_block an different parameters on the fly.
> I can do the nonGUI case, its OK. I just use wait() to identify when vector
> with test data is empty, to generate a new one and restart the flowgraph.
> But I can't wrap around how to involve the wxPython GUI - after starting
> MainLoop() I've no control any more on the top_block.
> What is needed:
> 1) during software run, change gr.vector_source data (get some notification,
> when its empty, then fill with new test-case-data, start again)
> 2) on each test-case, be able to adjust frequency, and gain of USRP2
> 3) give some graphical output of signal, for example, FFT.
>
> Q1)Is there some callback, when vector is empty (I didn't find one) or
> flowgraph is stopped due finished-data-stream? Or at least parameter? (the
> gr_vector_source.detail().done() just rises an error)
> Q2)Is there some callback from MainLoop() which "usually" is used?
> Q3)does it in general make sense to reconfigure and readjust flowgraph
> "fluently" or it is recommended some sleep time inbetween. Like, maybe, the
> gain of USRP2 just impossible to switch from 0 to 35 within 1ms. Or
> notification done() can be issued between data samples are really sent out
> by USRP, thus changing frequency at that time would be wrong.
>
> I also tried to start the grc_wxgui.top_block_gui in new thread and after
> run() tried to adjust parameters, without efforts. Also MainLoop() in
> different thread, no luck.
>
> Here down some very basic sample - if somebody can give hint to attach Scope
> to it, I would appreciate it a lot.
>
> Best regards from Bremen,
> diehortusxana
>
> ==================
> #!/usr/bin/env python
>
> from gnuradio import audio
> from gnuradio import eng_notation
> from gnuradio import gr
> from gnuradio.eng_option import eng_option
> from gnuradio.gr import firdes
> from optparse import OptionParser
> import time
> import math
>
> class my_basic_tb(gr.top_block):
>  def __init__(self):
>    gr.top_block.__init__(self)
>    self.samp_rate = samp_rate = 32000
>    self.audio_sink_0 = audio.sink(48000, "", True)
>    self.gr_vector_source_x_0 = gr.vector_source_f(gen_freq(41,1), False, 1)
>    self.connect((self.gr_vector_source_x_0, 0), (self.audio_sink_0, 0))
>
> def gen_freq(freq,len_s):
>    nv = []
>    for i in range(1,48000*len_s):
>      if math.fmod(i,freq) == 0:
>        nv.append(1)
>      else:
>        nv.append(0)
>    return nv
>
>
> if __name__ == '__main__':
>  parser = OptionParser(option_class=eng_option, usage="%prog: [options]")
>  (options, args) = parser.parse_args()
>
>  tb = my_basic_tb()
>  tb.start()
>  tb.wait()
>  print("done_part_1")
>  tb.lock()
>  tb.disconnect(tb.gr_vector_source_x_0)
>  tb.gr_vector_source_x_0 = gr.vector_source_f(gen_freq(11,1), False, 1)
>  tb.connect((tb.gr_vector_source_x_0, 0), (tb.audio_sink_0, 0))
>  tb.unlock()
>  tb.start()
>  print("reconfigured")
>  tb.wait()
>
>  print("Done")
> ===================


Instead of disconnecting the source, rebuilding it, and reconnecting
it, try to use the rewind() function on the source.

Also, yes, you'll want to put in some pause time when you update the
frequency/gain of the USRP.

Tom