Re: [Discuss-gnuradio] Locking USRP2 to external 10MHz reference in the UHD/GRC universe

[Josh Blum]

The capability is already there. If you need an example, take a look at 
the generated python code when you enable the ref clock for the uhd 
source or sink block in GRC. -Josh

On 11/21/2010 05:44 PM, Thomas Hobiger wrote:
> Hi Josh,
>
>
> I understand that the mimo blocks use the external ref automatically,
> but how to get this done with the UHD Single source block? In one of the
> prior mails you mentioned some Python code together with the XML wrapper
> changes. Can you tell me explicitly where to put that code?
>
> Regards,
> Thomas
>
> On 08/27/2010 01:28 AM, Josh Blum wrote:
> > The locking to external ref in the uhd mimo blocks is automatic. If
> > you are receiving samples, then the individual channels are aligned to
> > their timestamps. Otherwise gnuradio gets a 404 samples not found.
> >
> > You can also see the alignment if you look at magnitude of ch0 vs ch1
> > on a scope sink (assuming the RF input is identical). I have tested
> > this with Basic RX boards; what daughterboards are you using?
> >
> > -Josh
> >
> > On 08/26/2010 07:40 AM, Johannes Wenzel wrote:
> > > Hi,
> > >
> > > I'm using a mimo (2x2) USRP2 system. Both of the receiver USRP2
> > > receive a PPS- and a Clock-Signal provided by one GPS card. In grc I
> > > use the uhd_mimo_source block and two file_sink to receive and save
> > > the data sent. After starting RX the USRP2 mimo system seems to lock
> > > to the reference clock and reset the timer on PPS. Is this true? Or
> > > do I have to configure the block to do so? If I test the data with
> > > correlation it fails, which seems to be an indicator that at least
> > > the reference clock is not locked on.
> > >
> > > Is the uhd_mimo_source block automatically locked to external
> > > reference clock if used or do I have to configure it?
> > >
> > > Thanks
> > >
> > > Johannes.
> > >
> > > Am 23.08.2010 um 05:02 schrieb Josh Blum:
> > >
> > > > Swig brings in the clock config struct into python. The python code
> > > > looks like:
> > > >
> > > > > > > from gnuradio import uhd
> > > > > > > ccfg = uhd.clock_config_t()
> > > > > > > ccfg.ref_source = ccfg.REF_SMA
> > > > > > > ccfg.pps_source = ccfg.PPS_SMA
> > > > > > > ccfg.pps_polarity = ccfg.PPS_POS
> > > >
> > > > so the the grc xml wrapper you need that bit of code along with
> > > >
> > > > $(id).set_clock_config(ccfg)
> > > >
> > > > -Josh
> > > >
> > > > On 08/22/2010 04:52 PM, Marcus D. Leech wrote:
> > > > > How do I arrange to lock the USRP2 to an external 10MHz reference
> > > > > in the
> > > > > UHD+GRC world? Is there an "arg" I can pass when I
> > > > > create the UHD USRP2 simple source in GRC?
> > > > >
> > > > > This is for some pulsar research, where an external stable reference
> > > > > makes life soooo much easier.
> >
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