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    <p>Marcus,</p>
    <p><br>
    </p>
    <p>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.</p>
    <p><br>
    </p>
    <p>Mike<br>
    </p>
    <br>
    <div class="moz-cite-prefix">On 03/27/2019 11:10 AM, Marcus D. Leech
      via USRP-users wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:5C9B9249.4090709@gmail.com">
      <meta http-equiv="Content-Type" content="text/html;
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      <div class="moz-cite-prefix">On 03/27/2019 10:41 AM, Michael R.
        Freedman via USRP-users wrote:<br>
      </div>
      <blockquote
        cite="mid:9e9c3223-beab-df2a-18c0-3993caccb52c@ll.mit.edu"
        type="cite">
        <p>Any thoughts on this?</p>
        <p><br>
        </p>
        <p>Mike<br>
        </p>
      </blockquote>
      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<br>
        removal?  <br>
      <br>
      If you use offset tuning on the RX, do you still see a significant
      phase roll?<br>
      <br>
      <br>
      <blockquote
        cite="mid:9e9c3223-beab-df2a-18c0-3993caccb52c@ll.mit.edu"
        type="cite">
        <p> </p>
        <br>
        <div class="moz-cite-prefix">On 03/25/2019 01:04 PM, Michael R.
          Freedman via USRP-users wrote:<br>
        </div>
        <blockquote type="cite"
          cite="mid:20a82229-e454-707b-9dc7-ccc0b2a3b138@ll.mit.edu">
          <p>Marcus,</p>
          <p>   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.</p>
          <p><br>
          </p>
          <p>Mike<br>
          </p>
          <br>
          <div class="moz-cite-prefix">On 03/25/2019 12:34 PM, Nick
            Foster wrote:<br>
          </div>
          <blockquote type="cite"
cite="mid:CA+JMMq8i9R03HDe=5f+EjLs=DS3nnAJ4khOZvd9cNeqHbWsSZw@mail.gmail.com">
            <div dir="ltr">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.<br>
            </div>
            <br>
            <div class="gmail_quote">
              <div dir="ltr" class="gmail_attr">On Mon, Mar 25, 2019 at
                9:16 AM Michael R. Freedman via USRP-users <<a
                  href="mailto:usrp-users@lists.ettus.com"
                  moz-do-not-send="true">usrp-users@lists.ettus.com</a>>
                wrote:<br>
              </div>
              <blockquote class="gmail_quote" style="margin:0 0 0
                .8ex;border-left:1px #ccc solid;padding-left:1ex">
                <div text="#000000" bgcolor="#FFFFFF"> Hello,<br>
                  <br>
                  Do you have any suggestions as to how to measure the
                  frequency delta between the transmit channel and the
                  receive channel?<br>
                  <br>
                  As I sat down to do this, I realized I have no real
                  way to do that.</div>
                <div text="#000000" bgcolor="#FFFFFF"><br>
                  <br>
                  Mike<br>
                  <br>
                  <br>
                  <br>
                  <br>
                  <br>
                  <div class="m_-5534880283109296825moz-cite-prefix">On
                    03/24/2019 03:23 PM, Marcus D. Leech via USRP-users
                    wrote:<br>
                  </div>
                </div>
                <div text="#000000" bgcolor="#FFFFFF">
                  <blockquote type="cite">
                    <div class="m_-5534880283109296825moz-cite-prefix">On
                      03/24/2019 02:39 PM, Freedman, Michael - 1008 -
                      MITLL via USRP-users wrote:<br>
                    </div>
                    <blockquote type="cite">
                      <pre>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 <a class="m_-5534880283109296825moz-txt-link-rfc2396E" href="mailto:marcus.mueller@ettus.com" target="_blank" moz-do-not-send="true"><marcus.mueller@ettus.com></a> 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</pre>
                    </blockquote>
                    Also, what version of UHD?  What hardware rev of UBX
                    cards?<br>
                    <br>
                    <br>
                    <blockquote type="cite">
                      <pre>On Sat, 2019-03-23 at 17:06 -0400, Michael R. Freedman via USRP-users
wrote:
</pre>
                      <blockquote type="cite">
                        <pre>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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