On 03/27/2019 03:39 PM, Michael R. Freedman via USRP-users wrote:
Marcus,
I tried a 10MHz LOOffset with no change. I also tried it at 1155.0MHz
and 1160.0MHz. At 1155 the phase rolls... at 1160 it does not.
Mike
Could you give us a dump of uhd_usrp_probe for an X310 that displays
this issue? What version of UHD? Also, to be clear, this is within
a *single* X310, correct?
On 03/27/2019 11:10 AM, Marcus D. Leech via USRP-users wrote:
On 03/27/2019 10:41 AM, Michael R. Freedman via USRP-users wrote:
Any thoughts on this?
Mike
Given that in this case, the incoming carrier will be fighting
DC-offset removal rather hard, I wonder if this is a weird artifact
of DC-offset
removal?
If you use offset tuning on the RX, do you still see a significant
phase roll?
On 03/25/2019 01:04 PM, Michael R. Freedman via USRP-users wrote:
Marcus,
190Hz is what we calculated. I have attached a text file with
the data we used. This is a single UBX40 tuned to 155MHz sampling
at 2MHz.
Mike
On 03/25/2019 12:34 PM, Nick Foster wrote:
Well, according to your description, you could transmit a carrier
from TX to RX (through an attenuator) with both sides set to the
same frequency. Your received signal should look like a sine wave
at the frequency of the offset.
On Mon, Mar 25, 2019 at 9:16 AM Michael R. Freedman via USRP-users
<usrp-users@lists.ettus.com <mailto:usrp-users@lists.ettus.com>>
wrote:
Hello,
Do you have any suggestions as to how to measure the frequency
delta between the transmit channel and the receive channel?
As I sat down to do this, I realized I have no real way to do
that.
Mike
On 03/24/2019 03:23 PM, Marcus D. Leech via USRP-users wrote:
On 03/24/2019 02:39 PM, Freedman, Michael - 1008 - MITLL via
USRP-users wrote:
It is not just a phase offset. It is a frequency offset. The phase drifts
between the two. I can tolerate a phase offset at startup. A freq offset
however is causing problems.
Mike
Sent from my iPhone
On Mar 24, 2019, at 4:28 AM, Marcus Müller<marcus.muel...@ettus.com>
<mailto:marcus.muel...@ettus.com> wrote:
Can you elaborate on what "not coherent" means to you – the relative
phase should be constant after each tune, but if you don't tune
simultaneously, i.e. with timed commands, random at each tune.
Best regards,
Marcus
Also, what version of UHD? What hardware rev of UBX cards?
On Sat, 2019-03-23 at 17:06 -0400, Michael R. Freedman via USRP-users
wrote:
Hello,
I have an issue where I tune both the TX and RX side of a UBX40 card
in
an X310 to the same frequency and find that the transmitted signal
and
what is received are not coherent. I am using an external 10MHz
reference and have tried the documented suggestions.
at 150MHz it is coherent.
at 155MHz it is NOT coherent.
I have tried setting the dboard_clock_rate to 20MHz. This made the
problem appear at 150MHz as well. I've tried integer_n tuning.
I have verified that the ref_lock and lo_lock are both true.
Any suggestions?
Mike
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