Re: [Discuss-gnuradio] Problem with USRP!

[huzaifazafar108]

Dear Marcus,

I truly appreciate your prompt reply. However, I am not sure what should I
put in the 'modulus' field of the block. By hit and trial, wrong outputs are
emerging. Please guide.

Best Regards,
Huzaifa



Marcus D. Leech wrote:
> 
>> We just removed the throttle blocks and the same problem remains. Please
>> let
>> us know how to achieve symbol synchronization.
>>
>>
> Well, you're using DPSK, but not using a differential encoder on the TX 
> side, nor a differential decoder on the RX side.
> 
>> 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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>>>>
>>>>
> 
> 
> -- 
> Marcus Leech
> Principal Investigator
> Shirleys Bay Radio Astronomy Consortium
> http://www.sbrac.org
> 
> 
> 
> _______________________________________________
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> address@hidden
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> 
> 

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