Re: [Discuss-gnuradio] USRP continues to transmit after usrp_siggen.py stopped

[Eric Blossom]

On Mon, Jan 26, 2009 at 09:03:32PM -0800, Johnathan Corgan wrote:
> On Sun, Jan 25, 2009 at 9:21 PM, Kimminau Jr., Leo F. <address@hidden> wrote:
> 
> > Using a PowerMac G5 to control the USRP, if I stop usrp_siggen.py, the USRP
> > continues to transmit.  Is this expected?
> 
> No.
> 
> > This behavior is different than on a PowerBook G4, where the USRP stops
> > transmitting when usrp_siggen.py is stopped.
> 
> Can you elaborate on any other differences between the configurations?
>  OS version, GNU Radio version, developer tools (GCC, swig, Python),
> etc.?
> 
> Thanks
> 
> -Johnathan

I think this is a known problem (not sure there's a ticket on it).  I
believe that what is happening is that on the faster machine, the Tx
pipeline in the FPGA is getting disabled before it has a chance to
drain.  The result of this is that the pipeline is halted with a
non-zero constant value getting clocked into the DACs resulting in a
carrier for all daughterboards that contain an LO.

Eric