Re: [Discuss-gnuradio] tx_time tag accuraccy

[Martin Braun]

On 06/09/2014 06:05 AM, bob wole wrote:
> Can I have  a comment on it?

Bob,

we've given you a lot of information on this (see Tom's posts as a
start). If you still have questions, I recommend you start a new thread
and post exactly what you need to know and what your requirements are.

M
> 
> 
> --
> Bob
> 
> On Thu, Jun 5, 2014 at 11:02 AM, bob wole <address@hidden
> <mailto:address@hidden>> wrote:
> 
>     Sorry for not stating the hardware earlier. I am using USRP N210,
>     with RFX2400 and WBX boards.
>      
>     --
>     Bob
> 
>     On Wed, Jun 4, 2014 at 11:07 PM, Marcus Leech <address@hidden
>     <mailto:address@hidden>> wrote:
> 
>         I don't know the detailed answer, but any such answer will
>         depend very much on which USRP hardware you're talking about.
>          
>         One of the R&D people who deals with the FPGA codebase may be
>         able to give a precise answer, given stated hardware.
>          
>          
>          
>         on Jun 04, 2014, *bob wole* <address@hidden
>         <mailto:address@hidden>> wrote:
> 
>             Marcus! Thanks for you comment.
>              
>             I think that USRP transmit FIFO is at the start of the DSP
>             chain in FPGA i.e it is prior to both of the interpolation
>             filters? right?  I am not talking about when the burst will
>             be over the air, I want to know when the first sample of the
>             burst will leave the transmit FIFO if it has been tagged as
>             tx_time=X.
>              
>              
>              
>             --
>             Bob
> 
> 
>             On Wed, Jun 4, 2014 at 10:51 PM, Marcus Leech
>             <address@hidden <mailto:address@hidden>> wrote:
> 
>                 It will depend some on the effective group delay of both
>                 the interpolation filters in the the FPGA and the analog
>                 group delay of the analog bits of whatever daughtercard
>                 you're using.
>                  
>                 The only way to be sure is to measure...
>                  
>                  
>                 on Jun 04, 2014, *bob wole via USRP-users*
>                 <address@hidden
>                 <mailto:address@hidden>> wrote:
> 
>                     I am using stream tags for the transmission control.
>                     I want to know what is the accuracy/precision of the
>                     tx_time tag? E.g if I tag a burst A with tx_time=X,
>                     then the burst A will come out of the USRP transmit
>                     FIFO at X+delta, how large the value of delta could
>                     be? 
>                      
>                      
>                     --
>                     Bob
>                     
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