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<div class="document" id="uhd-calibration-application-notes">
<h1 class="title">UHD - Calibration Application Notes</h1>
<div class="contents topic" id="table-of-contents">
<p class="topic-title first">Table of Contents</p>
<ul class="simple">
<li><a class="reference internal" href="#self-calibration" id="id1">Self-Calibration</a><ul>
<li><a class="reference internal" href="#calibration-utilities" id="id2">Calibration Utilities</a></li>
<li><a class="reference internal" href="#calibration-data" id="id3">Calibration Data</a></li>
</ul>
</li>
</ul>
</div>
<div class="section" id="self-calibration">
<h1>Self-Calibration</h1>
<p>UHD software comes with several self-calibration utilities for minimizing IQ
imbalance and DC offset. These utilities perform calibration sweeps using
transmit leakage into the receive path (special equipment is not required).
The results from a calibration are written to a CSV file in the user's home
directory. UHD software will automatically apply corrections at runtime when
the user re-tunes the daughterboard LO. Calibration results are specific to an
individual RF board.</p>
<p><strong>Note:</strong>
When a calibration table is present,
and the user wishes to override the calibration settings through the API:
the user should re-apply the desired setting every time the LO is re-tuned.</p>
<p>UHD software comes with the following calibration utilities:</p>
<blockquote>
<ul class="simple">
<li><strong>uhd_cal_rx_iq_balance:</strong> - mimimizes RX IQ imbalance vs. LO frequency</li>
<li><strong>uhd_cal_tx_dc_offset:</strong> - mimimizes TX DC offset vs. LO frequency</li>
<li><strong>uhd_cal_tx_iq_balance:</strong> - mimimizes TX IQ imbalance vs. LO frequency</li>
</ul>
</blockquote>
<p>The following RF frontends are supported by the self-calibration utilities:</p>
<blockquote>
<ul class="simple">
<li>RFX Series transceiver boards</li>
<li>WBX Series transceiver boards</li>
<li>SBX Series transceiver boards</li>
<li>CBX Series transceiver boards</li>
</ul>
</blockquote>
<div class="section" id="calibration-utilities">
<h2>Calibration Utilities</h2>
<p>UHD software installs the calibration utilities into <strong><install-path>/bin</strong>.
<strong>Disconnect</strong> any external hardware from the RF antenna ports,
and run the following from the command line.
Each utility will take several minutes to complete.</p>
<pre class="literal-block">
uhd_cal_rx_iq_balance --verbose --args=<optional device args>
uhd_cal_tx_iq_balance --verbose --args=<optional device args>
uhd_cal_tx_dc_offset --verbose --args=<optional device args>
</pre>
<p>See the output given by --help for more advanced options, such as:
manually choosing the frequency range and step size for the sweeps.</p>
<p><strong>Note:</strong>
Your daughterboard needs a serial number to run a calibration utility. Some older daughterboards
may not have a serial number. If this is the case, run the following command to burn a serial number
into the daughterboard's EEPROM:</p>
<pre class="literal-block">
<install dir>/lib/uhd/utils/usrp_burn_db_eeprom --ser=<desired serial> --args=<optional device args>
</pre>
</div>
<div class="section" id="calibration-data">
<h2>Calibration Data</h2>
<p>Calibration files are stored in the user's home/application directory.
They can easily be moved from machine to another by copying the "cal" directory.
Re-running a calibration utility will replace the existing calibration file.
The old calibration file will be renamed so it may be recovered by the user.</p>
<blockquote>
<ul class="simple">
<li><strong>Linux:</strong> ${HOME}/.uhd/cal/</li>
<li><strong>Windows:</strong> %APPDATA%\.uhd\cal\</li>
</ul>
</blockquote>
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