Re: [Discuss-gnuradio] a little puzzled with setting rx mux...

[George Nychis]

Hi Vincenzo,

I believe that this is because you are now attempting 16MHz total 
bandwidth, 8 from each channel.  If you have a decimation rate of 8, you 
have 8Msps per second on one channel, and 8Msps on the other channel. 
The USB bus cannot handle this... it's not about your host computer.

- George


Vincenzo wrote:
> really thanks George,
>
> I figured it  out and it seems to work..
> now I'm wondering why, if I enable two channels from the usrp with :
>
>         if not self.u.set_nchannels(nchan):
>             sys.stderr.write('set_nchannels(%d) failed\n' % (nchan,))
>             raise SystemExit
>
>
> and attempt to transfer an 8 MHz bandwidth, the signals look and sound
> good (once demodulated) but I keep getting "uOuOuOs.." which are not
> there if the 2 channels are not enabled or the required bandidth is
> below 8 MHz. 
> (processing demand to the host computer is however far below the maximum
> allowed by my machine)
>
> thanks for help 
> vincenzo
>
> On Mon, 2008-02-18 at 10:34 -0500, George Nychis wrote:
> > Hi Vincenzo, 
> >
> > There is a method to the madness!
> > http://gnuradio.org/doc/doxygen/classusrp__standard__rx.html#346488ad15ddefa75900e4d0a63574cc
> >
> > Take a look at how each ddc is mapped.
> >
> > - George
> >
> >
> > -----Original Message-----
> > From: Vincenzo <address@hidden>
> > Sent: Monday, February 18, 2008 9:48 AM
> > To: gnuradio mailing list <address@hidden>
> > Subject: [Discuss-gnuradio] a little puzzled with setting rx mux...
> >
> > Hi,
> > I think I'm a bit confused about the meaning of instructions like
> >
> > self.u.set_mux(gru.hexint(0x01010101))
> > or
> > self.u.set_mux(gru.hexint(0xf3f2f1f0))
> >
> > I mean what exactly do I tell to the set_mux method by each single
> > {0,1,2,3,or f}? 
> >
> > does for exmample a 3 in the 4th position mean that adc3 is connected to
> > the Q channel of DDC 1?
> >
> > if so..
> > how can I obtain two demultiplated gr.complex flows coming from two
> > separate frontends (actually two DBSRX) one on rxA one and rxB side?
> >
> > would 
> >
> >         self.u.set_mux(gru.hexint(0x01230123))
> >         self.connect(self.u,deinterleaver)
> >         self.connect((deinterleaver,0),fft_sink1)
> >         self.connect((deinterleaver,1),fft_sink2)
> >
> > do what I need?
> >
> > really thanks
> > vincenzo
> >
> >
> >
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