Re: [Discuss-gnuradio] Syncronising multiple USRP2 boards

[MarcW]

Sorry im new at this - replied to message in wrong way.

Basically asked Tom whether he made any modifications to the firmware at all
and said I am interested in splitting the MIMO expansion signal from the
master 3+ ways possibly.

-Marc.




Tom Gross-3 wrote:
> 
> actually with our configuration we simply synchronize using the MIMO
> cable and setting one of the USRP2s to slave its clock to whatever the
> other one is using (I forget exactly how this is done but we do pretty
> much everything with GRC, so I think it's just in the source block for
> the USRP2 - I am not at the location with our system at the moment so
> I can't give you a better answer).
> 
> I'm pretty sure we are not using an external clock at all.  of course
> our configuration is specific to our application requirements - we use
> the second (slave) usrp2 to read a signal which is a function of the
> master's receive signal and its transmit signal (I am being
> deliberately vague).  I know that if I transmit from the master our
> system doesn't work (because I tried it).
> 
> -Tom
> 
> 
> On Wed, Jan 27, 2010 at 9:21 AM, MarcW <address@hidden> wrote:
>>
>> I would like to synchronise multiple USRP2 boards together. I know I need
>> a
>> 10Mhz reference clock and a synchronous 1PPS signal but have a few
>> questions
>> regarding the specifics of this,
>>
>> 1.) The USRP2 FAQ suggests to use a GPS clock but has anybody managed to
>> successfully use anything else such as a function generator or other
>> common
>> lab equipment?
>> 2.) Does the reference clock need to be a sine wave or can it be square
>> etc...?
>> 3.) What function should the PPS signal be?
>> 4.) Do I need to modify the FPGA firmware to enable locking from the
>> external signal?
>> 4.) Is an active splitter absolutely necessary to use or can i get by
>> with
>> passive?
>> 5.) Is there a good way to test whether I have correct synchronisation?
>>
>> Marc.
>> --
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>>
>>
>>
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