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<meta name="author" content="Keith Packard, Bdale Garbee">
-<meta name="copyright" content="Bdale Garbee and Keith Packard 2018">
+<meta name="copyright" content="Bdale Garbee and Keith Packard 2020">
<title>MicroPeak Owner’s Manual</title>
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</head>
<span id="email" class="email"><a href="mailto:keithp@keithp.com">keithp@keithp.com</a></span><br>
<span id="author2" class="author">Bdale Garbee</span><br>
<span id="email2" class="email"><a href="mailto:bdale@gag.com">bdale@gag.com</a></span><br>
-<span id="revnumber">version v1.9,</span>
-<span id="revdate">8 Oct 2018</span>
+<span id="revnumber">version v1.9.2,</span>
+<span id="revdate">26 Feb 2020</span>
</div>
<div id="toc" class="toc">
<div id="toctitle">Table of Contents</div>
<li><a href="#_setting_micropeak_preferences">2.4. Setting MicroPeak Preferences</a></li>
</ul>
</li>
+<li><a href="#_protecting_micropeak_from_sunlight">3. Protecting MicroPeak from Sunlight</a></li>
<li><a href="#_handling_precautions">Appendix A: Handling Precautions</a></li>
<li><a href="#_technical_information">Appendix B: Technical Information</a>
<ul class="sectlevel2">
</div>
</div>
<div class="sect1">
+<h2 id="_protecting_micropeak_from_sunlight">3. Protecting MicroPeak from Sunlight</h2>
+<div class="sectionbody">
+<div class="paragraph">
+<p>The MS5607 barometric sensor is sensitive to direct light. When light
+shines through the holes in the cover to the components inside, the
+reported pressure can vary wildly from the actual pressure. This
+causes the reported altitude to have errors of thousands of
+feet.</p>
+</div>
+<div class="paragraph">
+<p>MicroPeak should be installed in an opaque compartment in the airframe
+and not subjected to sunlight. Alternatively, a small piece of
+adhesive-backed open-cell foam can be attached to the device so that
+it covers the barometric sensor and protects it from direct light.</p>
+</div>
+<div class="paragraph">
+<p>Here’s what happens when MicroPeak is exposed to sunlight. At apogee,
+I exposed MicroPeak to varying amounts of sunlight and you can see the
+wild swings in altitude resulting from that:</p>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-flight-nofoam.png" alt="micropeak flight nofoam" width="430">
+</div>
+<div class="title">Figure 13. MicroPeak in Sunlight</div>
+</div>
+<div class="paragraph">
+<p>You can carefully cutting a piece of adhesive-backed open-cell foam
+and attach it to MicroPeak. It’s important to press the adhesive to
+the circuit board and not to the top of the barometric sensor or the
+sensor may become blocked and not operate at all. Once you’ve attached
+the foam, you should test MicroPeak on the ground to make sure it’s
+still working.</p>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-foam.jpg" alt="micropeak foam" width="430">
+</div>
+<div class="title">Figure 14. MicroPeak with Foam</div>
+</div>
+<div class="paragraph">
+<p>That MicroPeak was in the same barometric chamber as the one which
+generated the above results and the resulting flight data looks
+correct:</p>
+</div>
+<div class="imageblock">
+<div class="content">
+<img src="micropeak-flight-foam.png" alt="micropeak flight foam" width="430">
+</div>
+<div class="title">Figure 15. MicroPeak in Sunlight with Foam</div>
+</div>
+</div>
+</div>
+<div class="sect1">
<h2 id="_handling_precautions">Appendix A: Handling Precautions</h2>
<div class="sectionbody">
<div class="paragraph">
</div>
<div class="paragraph">
<p>The barometric sensor sampling ports must be able to
-"breathe", both by not being covered by foam or tape or other
-materials that might directly block the hole on the top of the
-sensor, and also by having a suitable static vent to outside
-air.</p>
+"breathe", both by not being covered by solid foam or tape or
+other materials that might directly block the hole on the top
+of the sensor, and also by having a suitable static vent to
+outside air.</p>
+</div>
+<div class="paragraph">
+<p>One good solution is to use a small rectangle of Poron
+50-30031-12X12P or equivalent to cover the sensor. This is an
+open cell foam in 1/32" thickness with an adhesive backing. It
+seems to do a good job of blocking sun while still allowing
+airflow to and from the sensor internals.</p>
</div>
<div class="paragraph">
<p>As with all other rocketry electronics, Altus Metrum
</div>
<div id="footer">
<div id="footer-text">
-Version v1.9<br>
-Last updated 2019-02-21 16:40:42 -0700
+Version v1.9.2<br>
+Last updated 2020-02-26 00:13:45 -0700
</div>
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