Re: [USRP-users] doubts about burst tranmission using tag SOB and EOB

[Marcus D. Leech via USRP-users]

I'll note that the "Message Burst Source" is now deprecated.  Not sure 
what it has been replaced with.   I've taken the liberty of cross-posting to

  discuss-gnuradio.


On 08/02/2017 02:05 PM, Yang Liu via USRP-users wrote:

Dear all,

I tried to achieve burst transmission on usrp X310, the brief tx 
flowgraph is in the below:


message_burst_source -> signal processing blocks --> usrp_sink

New message will be inserted into the message queue of 
message_burst_source.


Since message_burst_source will attach SOB and EOB tag to the data 
stream, usrp will know the start and end of each burst. After reading 
'Busrt Transmission' section in this link: 
https://gnuradio.org/doc/doxygen/classgr_1_1uhd_1_1usrp__sink.html, my 
understanding is that because of these two tags, even the two message 
arrives at usrp at a different time, usrp will not complain about 
underrun. However, according to results from my experiments, as the 
time difference between two contiguous message increases, underflow 
will show up and become more and more severe. For a real burst 
transmission, time gap between two message should be expected. 
Therefore, I feel confused about the using of SOB and EOB tags here. 
Can they help to remove "underrun" under burst transmission? If not, 
is there any other methods that can make burst transmission with usrp 
possible without triggering underrun?


Thanks a lot for your help,
Yang



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[USRP-users] doubts about burst tranmission using tag SOB and EOB

[Yang Liu via USRP-users]

Dear all,

I tried to achieve burst transmission on usrp X310, the brief tx flowgraph
is in the below:

message_burst_source -> signal processing blocks --> usrp_sink

New message will be inserted into the message queue of message_burst_source.

Since message_burst_source will attach SOB and EOB tag to the data stream,
usrp will know the start and end of each burst. After reading 'Busrt
Transmission' section in this link:
https://gnuradio.org/doc/doxygen/classgr_1_1uhd_1_1usrp__sink.html, my
understanding is that because of these two tags, even the two message
arrives at usrp at a different time, usrp will not complain about underrun.
However, according to results from my experiments, as the time difference
between two contiguous message increases, underflow will show up and become
more and more severe. For a real burst transmission, time gap between two
message should be expected. Therefore, I feel confused about the using of
SOB and EOB tags here. Can they help to remove "underrun" under burst
transmission? If not, is there any other methods that can make burst
transmission with usrp possible without triggering underrun?

Thanks a lot for your help,
Yang
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