Re: [Discuss-gnuradio] Packet Decoder block malfunction after demodulation!

[Vlad Stoianovici]

John,
I did the simulation of the receive - transmit flow, bypassing the Usrp sink
and source and putting in their place a Channel Model block and it works,
meaning that you were right.
This probably means that there is a problem with my USRP sink and source
parameters, probably the sample rate, which I am currently investigating.

Vlad.

John Andrews-5 wrote:
> 
> On Wed, Jun 15, 2011 at 9:53 AM, Vlad Stoianovici <
> address@hidden> wrote:
> 
>>
>> Dear list,
>> I'm using a typical UHD USRP source (USRP2) --> Low-Pass filter --> GMSK
>> Demod --> Packet Decoder --> File Sink receiver flow-graph in GnuRadio to
>> receive the signal I'm transmitting with a mirrored transmitting flow.
>> The problem is that the Packet Decoder (Output type - "byte"; Access Code
>> -
>> field left blank; Threshold -" -1") doesn't really do anything, the
>> signal
>> streams blocks there, and the file that the File Sink should create with
>> the
>> data from Packet Decoder is always empty.
>> The rest of the flow-graph seems to be working properly, I can visualize
>> the
>> received signal, that seems to be the same as the transmitted one.
>>
> 
> Are you sure its not doing what its supposed to do? Look at the work()
> function
> in your packet decoder. If the input doesn't fit the requirement of the
> algorithm to
> produce the output then it won't produce anything at its output. Think of
> it
> this way.
> Suppose the packet decoder block produces output items only when the input
> is greater
> than the threshold = T. If the input is constantly under T then there is
> nothing produced.
> 
> 
> If I take out the Packet Decoder, the file that results form the File Sink
>> has a size larger than 0 bytes, which leads me to believe that the
>> problem
>> is with this block.
>> Any ideas or similar problems?
>> Thanks,
>>
>> Vlad.
>>
> 
> 

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