On 10/18/2019 03:35 PM, Carlos Bocanegra wrote:
Hi all,
Thanks a lot Sam and Marcus for replying so quickly.
Le me first include Marcus answer in this email chain for a cleaner
communication:
"/Gnu Radio cannot really misalign samples, unless the DSP logic
arranges for that to happen. If you have a block with a bunch of
streams, that blocks "work" function cannot proceed until there is
equal amounts of data available on all streams. In the absence of the
hardware dropping samples, coherence is maintained in that case. What
you are seeing here seems to be a problem with your network stack
losing things. What type of Ethernet adapters do you have? What sample
rates are you running?/"
*The requested extra info:*
- The sampling rates selected are _1Msps_ for the TX and _2Msps_ for
the RX.
- The SFP connector attached to the USRP-X310s: AVAGO, 1.25GBd,
1000BASE-T, ABCU-5730ARZ.
- The NIC: Intel Corporation Gigabit CT Desktop Adapter.
- The Ethernet controller: Intel Corporation 82574L Gigabit Network
Connection.
@Marcus,
good thing that the scheduler in each block handles that correctly.
I'll focus on the network setup then.
@Sam,
it seems reasonable to think that the source of error is the poking
timeout, being the misalignment the aftermath.
When you say flow controls, do you mean the ones handled by the UHD fw
functions? I see a couple of D's (packet drops) right before the
misalignment error, after the UHD raises the last poking exception.
But maybe this is just the natural behavior- to drop misaligned
packets before either getting an alignment or timing out and rising
the exception.
"/Drop the sample rate (what is it, by the way?) and see if there's a
threshold where things start working [3]/":
Should I drop the samples below 1Msps/2Msps? I think these are pretty
low and having lower sampling rates would rise new problems. I can go
ahead and try it if you still thing this is the issue.
"/Keep the original sample rate and try removing a radio or two from
the system. Does this help things?/"/:/
- 4RX/1TX with simplistic flowgraph (usrp_source connected to
file_sinks and analog signal connected to usrp_sink): OK.
- 6RX/1TX with simplistic flowgraph (usrp_source connected to
file_sinks and analog signal connected to usrp_sink): NOK (error
described previously).
- 3RX/1TX with my DSP blocks: OK.
- 4RX/1TX with my DSP blocks: NOK (error described previously).
Regarding an example, I could not find one that sets up a usrp_source
AND a usrp_sink, in the folder {gr_prefix}/gr-uhd/examples/. I created
a simplistic python flowgraph that results in the poking and
misalignment issue, attached in this email. For instance, the 6x1
connections would map to the input argumments --tx_channels 1
--rx_channels 6.
Thanks a lot for your time and I hope to hear back from you soon.
Best,
Carlos
I'll note that some members of the 82574L family of controllers are
known to unnecessarily drop packets *particularly at unexpectedly-low flow
rates*.
This may or may not be contributing to your problem.
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