On 13/04/2023 17:02, Jim Schatzman wrote:
Even with all the recommended settings, and a very fast computer that is doing
nothing except sending the data, it is maybe 50/50 that a 2 hour simulation can
be conducted without an underrun. The longest run I have been able to do
without an underrun is about 2.5 hours.
The sample rate is 12.5 Msamp/sec at 16 bit I + 16 bit Q or 400 Mbit/sec.
For our application, that is unacceptable. I need to be able to run for days
without data loss.
It is a mystery to me why a 10 Gbit connection cannot support 400 Mbit/sec UDP
reliably.
Any ideas about how we can completely eliminate underruns?
At the moment, I am uncertain whether the problem is occurring on the host or
on the radio. I suspect the radio, but I will do some testing of the host to
see what UDP data rate it can support without loss.
Thanks!
With respect, it's unlikely to be the radio, per se (unless something is
BROKEN). Streaming is handled entirely by the
FPGA machinery, and unlike a general-purpose computer, running a
general-purpose OS, performance is utterly
deterministic. It doesn't have "other things" going on that might
preempt what it's doing, etc.
I think you'd mentioned that the hardware involved is a USRP N310?
While it does have a built-in LInux machine, since you're
using it from another host, the Linux machine is basically
uninvolved in streaming, other than session set-up and tear-down
via MPM.
Check the logs on your host machine--does the network interface go
up/down during your streaming? If so, that could
indicate a wiring problem.
Are you running in a native hardware machine, or in a VM? Windows or
Linux?
If you simply use the "tx_waveforms" example at your desired sample
rate, do you eventually get underruns or not?
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