On 2022-10-11 16:23, zhou wrote:
Thanks Marcus. Yes, I use the get_time_now function to read time
inside USRPs.
I also think the newer UHD versions should be better, but the
measurements tell differently. The queries to USRPs are sequential.
There are 16 USRPs using UHD 4.1.0. I query them sequentially and the
time intervals one example is as follows (unit: ms):
1.683691
1.606288
1.629145
1.790804
1.685894
1.736507
1.471674
1.424962
1.460004
1.403206
1.435221
1.394569
2.043707
1.509543
1.853792
In old system, 24 USRPs use UHD 3.10. The time intervals in one
example is (unit: ms):
0.385173
0.296745
0.284212
0.273682
0.278543
0.274327
0.279519
0.274441
0.276693
0.296875
0.275212
0.307623
0.309554
0.28233
0.28234
0.275119
0.283057
0.277138
0.279357
0.276074
0.277696
0.276335
0.280675
Though there is some variance in intervals in both systems, the
difference between old and new systems are significant and reliable.
Could you please pass my case to the R&D team to confirm?
Thanks,
Hongwei
On Tuesday, 11 October 2022 at 18:35:24 BST, Marcus D. Leech
<[email protected]> wrote:
On 2022-10-11 12:15, zhou via USRP-users wrote:
Hi,
Some of our USRPs are using UHD 3.10 because they are in old systems.
and I am also using UHD 4.1.0 in some other USRPs in new system. The
USRP products are all NI USRP 2944 (X310).
In my applications, I need to use PPS signal to synchronize multiple
USRPs. After applying PPS signals, I read back the time in USRPs one
by one. Because of network delay, there is some difference between the
readings. However, the difference is much bigger in UHD 4.1.0.
The interval between two USRPs using UHD 3.10 is about 0.2ms while it
is about 1.4ms in UHD 4.1.0
Does this mean that UHD 4.1.0 is slower than UHD 3.10?
Thanks for any suggestion,
Hongwei
Have you tried UHD 4.2 or UHD 4.3?
I'll point out that the performance-critical aspect is the streaming
performance. The latency on get_time_now() shouldn't matter
that much, unless you're trying to use it for synchronization, and
you really should be doing that. That's what set_time_next_pps()
and friends are for.
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