It is really dependent on what parameters you are trying to change. Some of them can change without stopping generation and others cannot.
As for changing the signal in real time, it is also dependent on a lot of things. There are always delays, no matter what hardware and software you are using, but it usually comes down to what is an acceptable amount of delay. If a couple of seconds is alright then the USRP 2900 should be able to serve all of your needs, if you need it to be on the order on microseconds or less then it might not do everything you need.
Either way you should check out the example: niUSRP EX Tx Continuous Async Reconfig on the Fly.vi, you can find it at the following location on your computer. Just replace LabVIEW 2017 with the version of LabVIEW you have. You also need to have NI-USRP installed.
C:\Program Files (x86)\National Instruments\LabVIEW 2017\examples\instr\niUSRP\niUSRP EX Tx Continuous Async Reconfig on the Fly.vi
This example shows some of the parameters that can be updated while generating. You will also notice that we write an array of complex doubles using the niUSRP Write Data VI. You could update this to write different data on each loop.
Again, the efficacy of this method to generate a real time signal is going to depend on what your constraints are. It will also depend on the performance of your computer.
Cheers
Michael Bilyk
Former NI Software Engineer (IT)
