Re: [Discuss-gnuradio] reconfigure flow graph with scope app

[Larry Wagner]

Hi Eric -

Thank you for your reply. I incorrectly used the wording offset 
between the 2 daughter cards where I meant to say that the absolute 
offset (of the 2 daughter cards) is unknown at the start of a run. 
This has been observed after many experiments so far with my 
interferometer like project and causes a run to run inconsistency.

I have worked out a calibration procedure where I begin with a known 
geometry (transmitter to receiver placement) and observe the scope; 
and then reconfigure the flow graph by a keypress without stopping 
the app. This will be accomplished by use of "app.set_volume()"  in 
the main program and a "def set_volume(self, volume):" in the flow 
graph that includes the scope as a sink.

The modifications to the main part of multi_scope.py that I have 
tried are below. When I run this I get a scope but do not get the 
prompt in the terminal window. When I click on the close window of 
the scope window I do get the prompt.

def main ():
    app = stdgui2.stdapp (test_top_block, "O'Scope Test App")
    app.MainLoop ()
    raw_input ('Press Enter to end CALIBRATE and start RUN (amplify x now):')
    raw_input ('Press Enter to stop: ')
    app.stop()

if __name__ == '__main__':
    main ()

# ----------------------------------------------------------------

Take care,
  - Larry

At 03:40 PM 1/26/2009, Eric Blossom wrote:
> On Sun, Jan 25, 2009 at 11:34:34PM -0800, Larry Wagner wrote:
> > Hi -
> >
> > I have a USRP with 2 RFX2400 daughter cards and need to calibrate the
> > local oscillator (LO) offset between them. To do this I want to modify
> > the multi_scope.py example to allow me to reconfigure the flow graph
> > without stopping. This is based on some external measurement I will do
> > followed by a keypress and possibly an input using raw_input().
>
> Larry,
>
> If the 2 RFX2400 cards are attached to the same USRP, there will be no
> LO offset between them. They are driven by a common ref clock provided
> by the USRP motherboard.
>
> Eric