IQ Rate on MIMO OFDM using NI-USRP 2920

[nihay1710]

I have this error
"niUSRP Write Tx Data (2D CDB).vi<ERR>Underflow: the Tx buffer was emptied before new data was provided.  Consider reducing the IQ rate, increasing the Write rate, or increasing the number of samples per Write."
What is the solution for this error? 
After I add some script in mathscript, the programm has error.
Is there any relation with the addition of script on mathcript?

Nihayatus

[GerdW]

Hi nihay,

the Tx buffer was emptied before new data was provided.

So the transmit (output) buffer was empty before you provided new data for transmitting…

After I add some script in mathscript, the programm has error.
Is there any relation with the addition of script on mathcript?

Ok, you made your VI slower by adding more code - and now you wonder because the hardware is complaining about not getting new data fast enough? Might there be a relation between your (slow) code and that error???

Simple solution: provide new data fast enough to avoid this empty Tx buffer!

[nihay1710]

Can this error be solved by setting the IQ rate, number of sample per write?

[GerdW]

Hi nihay,

the error is due to not delivering new data fast enough for transmitting.

You can solve this error by:

- delivering the data fast enough: do you really need this (slow?) mathscript node?

- lowering the sample rate: now you get more time to deliver the same amount of data

- increasing the buffer: now you get more time for calculation, but you need to provide more samples. In the end you don't gain much here…

The best solution is to improve the data generation routine to calculate the samples faster!