<div dir="ltr"><div>NB:</div><div><br></div>Even the Simple Magnetometer Magnetometer Support Boards (SMSBs) should be able to avoid this problem if attached using the <a href="https://www.sparkfun.com/products/14429">Qwiic Cable - 500mm</a>, the <a href="https://www.sparkfun.com/products/14428">Qwiic Cable - 200mm</a>, or their equivalents from AdaFruit. I believe that I provided one or the other of these with any of the boards I sent out for testing. Care in positioning is left up to the user.<div><br></div><div>The problem probably only applies to upcoming raspberry-pi hats in local mode (with the magnetometer sitting on top of the pi). But in some non-professional cases, convenience may outweigh the loss of sensitivity, esp functional testing.</div><div>People in the Drone community claim to have used uMetal for shielding to good effect (from PM motors, etc) but this does not sound like good practice for sensitive instruments.<br><div><br></div><div>And anyone using these boards in the remote extender configuration will find it difficult to place the far end board that close with any amount of shielded Cat-6 in between.</div><div><br></div><div>Dave</div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, May 28, 2020 at 11:00 AM <<a href="mailto:tangerinesdr-request@lists.tapr.org">tangerinesdr-request@lists.tapr.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Send TangerineSDR mailing list submissions to<br>
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Today's Topics:<br>
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1. Raspberry Pi connectors produce magnetic interference<br>
(Phil Erickson)<br>
<br><br><br>---------- Forwarded message ----------<br>From: Phil Erickson <<a href="mailto:phil.erickson@gmail.com" target="_blank">phil.erickson@gmail.com</a>><br>To: TAPR TangerineSDR Modular Software Defined Radio <<a href="mailto:tangerinesdr@lists.tapr.org" target="_blank">tangerinesdr@lists.tapr.org</a>><br>Cc: <br>Bcc: <br>Date: Thu, 28 May 2020 08:45:18 -0400<br>Subject: [TangerineSDR] Raspberry Pi connectors produce magnetic interference<br><div dir="ltr">Hi all,<div><br></div><div> For those working on the PSWS magnetometer project, I'd like to pass along some findings made by Nick Belsten (MIT student) on our AERO/VISTA cube satellite team. As background, AERO/VISTA is a twin cubesat mission with the goal of investigating the radio aurora at 400 kHz to 5 MHz in low Earth orbit, and will fly in 2022 through the NASA Heliophysics small satellite explorer program. MIT Haystack is the lead with MIT Lincoln Laboratory providing the advanced electromagnetic vector sensor package. Other participants include Dartmouth, Merrimack College, Morehead State University, and MIT AeroAstro.</div><div><br></div><div> Each of the two cubesats will have an Auxiliary Sensor Package for coincidence detection of the aurora (other than radio) that includes a magnetometer. Nick has been in charge of some of the magnetometer package development, and reports that stock Raspberry Pi connectors contain steel that is magnetized and that causes deflections on the order of 2 uT at 3 cm distance. Given scaling laws, it is therefore recommended to keep the magnetometer at least 8-10 cm away from Raspberry Pi hardware to avoid systematic bias or possible degradation in uncertainty if you are targeting 50 nT type measurement capabilities.</div><div><br></div><div> Nick is writing a memo on his findings and procedure so please contact me off-list if you would like to hear from him directly.</div><div><br></div><div> Just an caveat / advisory note (perhaps not relevant) if anyone is running a test configuration with magnetometers next to a R-Pi, rather than at the end of a long cable. Perhaps it's also prudent to examine the magnetic characteristics of connectors on the TangerineSDR?</div><div><br></div><div>73</div><div>Phil W1PJE</div><div><div><br></div>-- <br><div dir="ltr">----<br>Phil Erickson<br><a href="mailto:phil.erickson@gmail.com" target="_blank">phil.erickson@gmail.com</a><br></div></div></div>
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