Hi Wade,
Thanks for the information. I will try UHD 4.2.
Kind regards,Hongwei
On Wednesday, 12 October 2022 at 14:29:00 BST, Wade Fife
<[email protected]> wrote:
There was a change related to how get_time_now was implemented in UHD 4.0 but
that was improved in UHD 4.2. I would expect the behavior in 4.2 to be more
like 3.15 and earlier.
Wade
On Wed, Oct 12, 2022 at 3:24 AM zhou via USRP-users
<[email protected]> wrote:
Hi Marcus,
Different OS/kernels in the two systems.In old system with UHD 3.10, the
OS/kernel are Ubuntu 16.04.6 LTS (GNU/Linux 4.4.0-176-lowlatency x86_64)In new
system with UHD 4.1.0, the OS/kernel are Ubuntu 18.04.5 LTS (GNU/Linux
5.4.0-80-lowlatency x86_64)
On Tuesday, 11 October 2022 at 23:11:50 BST, Marcus D Leech
<[email protected]> wrote:
Is it the same OS/kernel version in both cases?
Sent from my iPhone
On Oct 11, 2022, at 5:53 PM, zhou <[email protected]> wrote:
Hi Marcus,
I haven't tried UHD 4.2 or 4.3. I see ULLL sometimes in new system, so actually
I am thinking reverting UHD back to the 3.10.
On Tuesday, 11 October 2022 at 21:47:30 BST, Marcus D. Leech
<[email protected]> wrote:
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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