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    <div class="moz-cite-prefix">On 03/12/2019 10:26 AM, Ivan Zahartchuk
      wrote:<br>
    </div>
    <blockquote
cite="mid:CAPRRyxs36fC7Y7yUJBPd_jLhMMn7G6mCbfRTk5_5j4ZK=ku24Q@mail.gmail.com"
      type="cite">
      <div dir="ltr"><span class="gmail-tlid-translation
          gmail-translation"><span title="" class="gmail-">Sorry, but I
            do not fully understand how to work with frequency offset.</span>
          <span title="" class="gmail-">For example, I have an
            instantaneous bandwidth of 25 MHz.</span> <span title="">Then
            I set the frequency offset to 13 MHz?</span> <span title=""
            class="gmail-">Because my amplitude decreases, but the peak
            still remains with a large amplitude.</span></span></div>
    </blockquote>
    Here is the API documentation for tuning:<br>
    <br>
    <a class="moz-txt-link-freetext" href="https://files.ettus.com/manual/structuhd_1_1tune__request__t.html">https://files.ettus.com/manual/structuhd_1_1tune__request__t.html</a><br>
    <br>
    If you are using an offset, with that API, and you still have a peak
    at the notional center frequency, then it is NOT DC offset, but
    coming<br>
      from somewhere else.<br>
    <br>
    <br>
    <blockquote
cite="mid:CAPRRyxs36fC7Y7yUJBPd_jLhMMn7G6mCbfRTk5_5j4ZK=ku24Q@mail.gmail.com"
      type="cite"><br>
      <div class="gmail_quote">
        <div dir="ltr" class="gmail_attr">вт, 12 мар. 2019 г. в 15:13,
          Marcus D. Leech via USRP-users <<a moz-do-not-send="true"
            href="mailto:usrp-users@lists.ettus.com">usrp-users@lists.ettus.com</a>>:<br>
        </div>
        <blockquote class="gmail_quote" style="margin:0px 0px 0px
          0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
          <div bgcolor="#FFFFFF">
            <div class="gmail-m_2556126236602897378moz-cite-prefix">On
              03/12/2019 05:13 AM, Ivan Zahartchuk via USRP-users wrote:<br>
            </div>
            <blockquote type="cite">
              <div dir="ltr"><span
                  class="gmail-m_2556126236602897378gmail-tlid-translation
                  gmail-m_2556126236602897378gmail-translation"><span
                    title="">Thanks for the information.</span> <span
                    title="">But do not tell me why then in N 210 with
                    sbx there is no such problem?</span> <span title=""
                    class="gmail-m_2556126236602897378gmail-">Just in
                    the N 210 I am not satisfied with the large central
                    frequency. As I understand this is a surge in direct
                    current.</span> <span title=""
                    class="gmail-m_2556126236602897378gmail-">But I
                    can't get rid of him.</span> <span title="">And
                    sometimes there are problems with the mirror
                    channel.</span> <span title=""
                    class="gmail-m_2556126236602897378gmail-">If you
                    have any advice on this, I will be extremely
                    grateful.</span></span></div>
            </blockquote>
            Because the SBX is a different piece of hardware, with
            different architecture.  It happens to tune a lot faster.<br>
            <br>
            The DC offset can be dealt with using offset tuning:<br>
            <br>
            <a moz-do-not-send="true"
              class="gmail-m_2556126236602897378moz-txt-link-freetext"
              href="https://files.ettus.com/manual/page_general.html"
              target="_blank">https://files.ettus.com/manual/page_general.html</a><br>
            <br>
            If you are seeing image frequencies, then use the <br>
            <br>
            uhd_cal_rx_iq_balance<br>
            <br>
            Utility on your N210 to caclulate and record calibration
            parameters that will help to reduce I/Q imbalance.  DC
            offset and I/Q imbalance are<br>
              inherent in a direct-conversion receiver design.  These
            imbalances need to be calibrated out.  In the N210/SBX,
            host-side software does<br>
              "static' measurement of these (using the above mentioned
            tooling) and records a calibrations file.  Those
            calibrations are then applied<br>
              at run-time to compensate.<br>
            <br>
            In the B210, the AD9361 chip does I/Q correction (and other
            corrections) dynamically, which can cause it to be slower in
            tuning--because it<br>
              does the measurements whenever you re-tune.<br>
            <br>
            See:<br>
            <br>
            <a moz-do-not-send="true"
              class="gmail-m_2556126236602897378moz-txt-link-freetext"
href="https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms1-ebz/iq_correction"
              target="_blank">https://wiki.analog.com/resources/eval/user-guides/ad-fmcomms1-ebz/iq_correction</a><br>
            <br>
            For a discussion<br>
            <br>
            <blockquote type="cite"><br>
              <div class="gmail_quote">
                <div dir="ltr" class="gmail_attr">пн, 11 мар. 2019 г. в
                  17:17, Ian Buckley <<a moz-do-not-send="true"
                    href="mailto:ianb@ionconcepts.com" target="_blank">ianb@ionconcepts.com</a>>:<br>
                </div>
                <blockquote class="gmail_quote" style="margin:0px 0px
                  0px 0.8ex;border-left:1px solid
                  rgb(204,204,204);padding-left:1ex">Ivan,<br>
                  When the AD9361 is retuned, recalibration of various
                  RF circuits may (need to) reoccur. The device driver
                  looks how far you have retuned from a previous
                  frequency, and if it exceeds a certain distance
                  rerun’s this calibration, which takes time.<br>
                  Since Analog devices envisaged that this chip might
                  need to be used in applications where fast hopping is
                  required, it does have the ability to store multiple
                  calibration settings locally in the radio and switch
                  between them quickly, but this is not functionality
                  that is used in basic operation under UHD. We may well
                  have put API hook’s in there so you can manually call
                  this functionality under UHD, but I can’t recall. Take
                  a look at ADI’s documentation for more info.<br>
                  <br>
                  -Ian<br>
                  <br>
                  > On Mar 11, 2019, at 7:49 AM, Ivan Zahartchuk via
                  USRP-users <<a moz-do-not-send="true"
                    href="mailto:usrp-users@lists.ettus.com"
                    target="_blank">usrp-users@lists.ettus.com</a>>
                  wrote:<br>
                  > <br>
                  > Hello. I have a problem with the usrp b200 board.
                  I need a fast frequency tuning for spectrum analysis.
                  But when I increase the band over 200 MHz, that is,
                  more than 8 frequency adjustments, I have problems
                  with time. It increases dramatically.<br>
                  > Here is the code section where I measure the
                  execution time of the frequency setting function:<br>
                  > for i, freqq in enumerate (freq):<br>
                  > <br>
                  >             recv_samps = 0<br>
                  >             self.usrp.set_rx_rate (bandwich [i])<br>
                  >             start = time.time ()<br>
                  >             self.usrp.set_rx_freq
                  (lib.types.tune_request (freqq))<br>
                  > <br>
                  >             print (time.time () - start)<br>
                  > And I get the following results:<br>
                  > 0.154153108597<br>
                  > 0.00300002098083<br>
                  > 0.0029628276825<br>
                  > 0.00299215316772<br>
                  > 0.00298380851746<br>
                  > 0.153974056244<br>
                  > 0.153841018677<br>
                  > 0.00304222106934<br>
                  > 0.00305104255676<br>
                  > 0.0030951499939<br>
                  > 0.0030038356781<br>
                  > 0.153944015503<br>
                  > 0.153861045837<br>
                  > 0.00292587280273<br>
                  > 0.00306510925293<br>
                  > 0.00301003456116<br>
                  > 0.0029399394989<br>
                  > With USRP N 210 there is no such problem. Tell me
                  why this problem occurs and how can it be solved?<br>
                  > Thanks in advance. Ivan<br>
                  > _______________________________________________<br>
                  > USRP-users mailing list<br>
                  > <a moz-do-not-send="true"
                    href="mailto:USRP-users@lists.ettus.com"
                    target="_blank">USRP-users@lists.ettus.com</a><br>
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