On 11/22/2020 10:30 AM, Cameron Matson wrote:
Marcus,
Yes it was all coming out of the same uhd_source object. I think I
was able to resolve the issue for now by setting the "Sync" parameter
to "unknown PPS" which I /believe/ is using the White Rabbit Ethernet
based timing synchronization which we have connected at one of the SFP
ports, though I need to dig in a bit more into the API.
I agree 20 ms is *HUGE*; is it unexpected even without an external
timing source? Should I still be concerned?
Thanks,
Cameron
Actually, this isn't unexpected. For architectural reasons, there is a
timstamp clock for each RF chain in th device--those clocks
need to b synchronized, so a "set_time_next_pps" will take care of that.
On Fri, Nov 20, 2020 at 12:43 PM Marcus D. Leech
<patchvonbr...@gmail.com <mailto:patchvonbr...@gmail.com>> wrote:
On 11/20/2020 11:49 AM, Rob Kossler wrote:
Hi Cameron,
Yes, this is possible. I'm not too familiar with gnuradio but in
the end you need to use a "timed start" to the receive streams.
Rob
On Fri, Nov 20, 2020 at 7:34 AM Cameron Matson via USRP-users
<usrp-us...@lists.ettus.com <mailto:usrp-us...@lists.ettus.com>>
wrote:
Hello all,
I'm trying to implement a MIMO receiver using the 4 RF chains
of the N310. To test the timing of the system, at the
transmitter I'm simply sending a short pulse from one
transmit antenna of one USRP. At the receiver it looks like
there is up to a ~20 ms delay/offset between the pairs of
antennas 0/1 and 2/3 and that this delay changes each time I
restart my GNURadio flowgraph. I can see the delay both in
GNURadio GUI Time Sink and in actual samples that I write to
file. I've tried various pulse widths and sampling rates at
both the tx and rx, and it seems invariant to these.
I'd really like to be able to synchronize the 4 RF chains in
time simultaneously. Is that possible?
Thanks
Cameron Matson
_______________________________________________
Cameron:
Can you share a simple Gnu Radio flow-graph that displays this
behavior? A 20ms offset is *HUGE*. Are all 4 streams being
streamed out
of the same uhd_source object?
