Re: [Discuss-gnuradio] Problem with USRP!

[huzaifazafar108]

We just removed the throttle blocks and the same problem remains. Please let
us know how to achieve symbol synchronization.



huzaifazafar108 wrote:
> 
> Dear John,
> 
> Thank you for such a prompt reply. Okay, we will remove the throttle
> blocks just now. But can you guide us how to achieve symbol
> synchronization then?
> 
> Best Regards, 
> Huzaifa
> 
> 
> 
> John Malsbury wrote:
>> 
>> You do not need to use throttles when using a UHD sink/source, because 
>> the device provides timing for the flowgraph.
>> 
>> Remove the throttles and try again.  If you still see the failure I'd 
>> say you are not achieving symbol sync.
>> 
>> -John
>> 
>> 
>> 
>> On 04/08/2012 01:58 PM, Huzaifa Zafar wrote:
>>> Dear all,
>>>
>>> I am working with 3 people on a project involving GNU Radio and USRP1. 
>>> We have tried to implement a simple point to point digital 
>>> communication system in GRC involving DQPSK modulation. Using a vector 
>>> source we are sending a finite stream of zeros and ones (the vector 
>>> source has Repeat set to yes). On the receiver side, what we receive 
>>> is really very strange: The same stream of zeros and ones, but with 
>>> extra zeros in between our actual data. For example, we send three 
>>> ones and three zeros, but what we receive is a one followed by seven 
>>> zeros, another one followed by seven zeros, another one followed by 
>>> seven zeros, and then a zero followed by seven zeros e.t.c. We tried 
>>> to experiment more by using the 'KEEP 1 in N' block and the 
>>> 'DECIMATING FIR FILTER', but things are not working out the way they 
>>> should.
>>>
>>> I am also attaching a snapshot of the .grc file for your reference. 
>>> Please tell us the reason why these extra zeros are present between 
>>> our data bits, and the way to combat this effect (remember that the 
>>> decimating fir filter and keep 1 in N block are not showing the 
>>> desired output). Any kind of help is appreciated in advance.
>>>
>>> -- 
>>> Huzaifa Zafar
>>>
>>>
>>> _______________________________________________
>>> Discuss-gnuradio mailing list
>>> address@hidden
>>> https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
>> 
>> 
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>> 
> 

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