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<font face="Arial">Don't forget, Dave W's software output is in
microteslas and mapping from the standard RM3100 board horizontal
with pins down and the white arrow in the upper left hand corner
of the PC board indicating magnetic north orientation, is the
responsibility of the user. <br>
<br>
The RM3100 is capable of better than 10nT resolution with the
proper polling settings and post processing in a relatively quiet
environment.<br>
Jules-K2KGJ<br>
</font><br>
<div class="moz-cite-prefix">On 6/30/2021 6:00 PM,
<a class="moz-txt-link-abbreviated" href="mailto:tangerinesdr-request@lists.tapr.org">tangerinesdr-request@lists.tapr.org</a> wrote:<br>
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Today's Topics:
1. Re: [EXTERNAL] Re: Getting rid of magnetometer-related RF
noise (Bill Engelke)
2. Re: EXT: Re: Magnetometer tests (David Waugh)
----------------------------------------------------------------------
Message: 1
Date: Wed, 30 Jun 2021 20:42:21 +0000
From: Bill Engelke <a class="moz-txt-link-rfc2396E" href="mailto:bill.engelke@ua.edu"><bill.engelke@ua.edu></a>
To: TAPR TangerineSDR Modular Software Defined Radio
<a class="moz-txt-link-rfc2396E" href="mailto:tangerinesdr@lists.tapr.org"><tangerinesdr@lists.tapr.org></a>
Subject: Re: [TangerineSDR] [EXTERNAL] Re: Getting rid of
magnetometer-related RF noise
Message-ID:
<a class="moz-txt-link-rfc2396E" href="mailto:BN8PR15MB318505EBE7AD76C337B80001FA019@BN8PR15MB3185.namprd15.prod.outlook.com"><BN8PR15MB318505EBE7AD76C337B80001FA019@BN8PR15MB3185.namprd15.prod.outlook.com></a>
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Alan ? with
* The magnetometer buried at 2 feet depth
* Running shielded CAT6 cable grounded at the R-Pi
I have tested (with the magnetometer running at recommended parameters) on 160 M through 10 M (at 1 KW), on 6M (at 500W) and on 2M (at 50 W) and so far I have not seen any perturbations of the magnetometer from carriers at these bands & power levels.
It has been suggested to me that I try doing some modulation and see if that makes a difference; I still have to run that s of tests. -73- Bill, AB4EJ
From: TangerineSDR <a class="moz-txt-link-rfc2396E" href="mailto:tangerinesdr-bounces@lists.tapr.org"><tangerinesdr-bounces@lists.tapr.org></a> On Behalf Of n5pa via TangerineSDR
Sent: Wednesday, June 30, 2021 2:39 PM
To: TAPR TangerineSDR Modular Software Defined Radio <a class="moz-txt-link-rfc2396E" href="mailto:tangerinesdr@lists.tapr.org"><tangerinesdr@lists.tapr.org></a>
Cc: n5pa <a class="moz-txt-link-rfc2396E" href="mailto:n5pa.dx.341@gmail.com"><n5pa.dx.341@gmail.com></a>; Bill Engelke <a class="moz-txt-link-rfc2396E" href="mailto:bill.engelke@ua.edu"><bill.engelke@ua.edu></a>
Subject: [EXTERNAL] Re: [TangerineSDR] Getting rid of magnetometer-related RF noise
Good info to know Bill! I run QRO on most bands and I am concerned about getting into the magnetometer, also.
73,
Alan Clark, N5PA
Ellisville, MS
Email: <a class="moz-txt-link-abbreviated" href="mailto:n5pa@n5pa.com">n5pa@n5pa.com</a><a class="moz-txt-link-rfc2396E" href="mailto:n5pa@n5pa.com"><mailto:n5pa@n5pa.com></a>
URL: <a class="moz-txt-link-freetext" href="http://www.n5pa.com">http://www.n5pa.com</a><a class="moz-txt-link-rfc2396E" href="https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.n5pa.com%2F&data=04%7C01%7Cbill.engelke%40ua.edu%7C6b803b5bdba9466007b308d93bfee3a9%7C2a00728ef0d040b4a4e8ce433f3fbca7%7C0%7C0%7C637606788214030979%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=IiYe6jSmasEixXVMkrtZN5syd81aSudnMee2jYMfr8g%3D&reserved=0"><https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.n5pa.com%2F&data=04%7C01%7Cbill.engelke%40ua.edu%7C6b803b5bdba9466007b308d93bfee3a9%7C2a00728ef0d040b4a4e8ce433f3fbca7%7C0%7C0%7C637606788214030979%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=IiYe6jSmasEixXVMkrtZN5syd81aSudnMee2jYMfr8g%3D&reserved=0></a>
On Jun 30, 2021, at 1:25 PM, Bill Engelke via TangerineSDR <<a class="moz-txt-link-abbreviated" href="mailto:tangerinesdr@lists.tapr.org">tangerinesdr@lists.tapr.org</a><a class="moz-txt-link-rfc2396E" href="mailto:tangerinesdr@lists.tapr.org"><mailto:tangerinesdr@lists.tapr.org></a>> wrote:
?
To all:
You might recall that a few weeks ago I discovered some RF noise appearing on 160 M and 80 M when the magnetometer was hooked up. This was wideband noise on 80M and a birdie on 160M.
Note that I have been using shielded CAT6 cable between the magnetometer base (a Pi-Hat) and the in-ground magnetometer. The noise could be seen clearly in the waterfall on my FlexRadio 6600 connected to my 80M dipole; it was only 1 to 2 s-units, but this might be an issue for DXing.
It required 2 steps to eliminate this noise:
1. The ground plane of the R-Pi needs to be connected to an earth ground. This eliminates the birdie on 160M and cuts the 80M noise about in half. Do this by grounding the sleeve of the R-Pi audio jack.
2. The remaining 80M noise is due to the Canakit switching power supply that comes in a Raspberry Pi kit. To eliminate that, you must replace the switching power supply with a linear power supply. I found a 4.5 amp linear supply (Pyramid brand, on Amazon $55.79) that has 2 USB jacks (each able to supply 2 amps) plus 13.8 V terminals.*
-73- Bill, AB4EJ
* There are cheaper linear power supplies, but R-Pi recommends a supply able to provide 3 amps. Linear power supplies able to provide 3 a are not plentiful or cheap. I measured the actual current pulled by a R-Pi 4 B+, and it is around 1 amp. With the Pyramid supply I am powering two R-Pi 4 B+ computers with power to spare, and the switching noise is gone.
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Message: 2
Date: Wed, 30 Jun 2021 17:59:54 -0400
From: David Waugh <a class="moz-txt-link-rfc2396E" href="mailto:dwaugh@kent.edu"><dwaugh@kent.edu></a>
To: TAPR TangerineSDR Modular Software Defined Radio
<a class="moz-txt-link-rfc2396E" href="mailto:tangerinesdr@lists.tapr.org"><tangerinesdr@lists.tapr.org></a>
Cc: n5pa <a class="moz-txt-link-rfc2396E" href="mailto:n5pa.dx.341@gmail.com"><n5pa.dx.341@gmail.com></a>, Julius Madey <a class="moz-txt-link-rfc2396E" href="mailto:hillfox@fairpoint.net"><hillfox@fairpoint.net></a>
Subject: Re: [TangerineSDR] EXT: Re: Magnetometer tests
Message-ID: <a class="moz-txt-link-rfc2396E" href="mailto:9A246DC1-D5B3-4A13-81FC-18AFD7E62444@kent.edu"><9A246DC1-D5B3-4A13-81FC-18AFD7E62444@kent.edu></a>
Content-Type: text/plain; charset="utf-8"
N5PA was interested in the what the lawnmower would do, and I had a chance to look at that. The image below (I?m not positive the list can take attachments) is a crude and not proofread illustration of the data. My mower is just a steal deck battery powered self-propelled mower that looks like a normal gas push mower. The times indicated by the vertical red lines were inserted into the timeline based on timestamps of photos from my cell phone, so for the two ?big? events there is a lag between me fumbling with the phone and getting the photo. Below the first panel of graphs is all the data I have for that day to provide some context. So it?s clear that when the mower was really close to the magnetometer (and stationary), it produced a large signal, but when examined in context of the day it was just a very minor spike that I?m guessing could be easily ignored. By the time I was working on the central part of the yard, the signal hardly shows up.
I?ve got more data on parked cars which seem to have a larger, or at least more persistent signal, although in an initial test a car about 70 feet away produced very little, if any signal, I would like to narrow down what that distance really is. Cars within ~32 feet still create a signal, although I don?t know to what extent that would degrade the usefulness of the data (that would be an interesting conversation to have with those using the data). -David KE8QEP
David A. Waugh, Ph.D.
Research Assistant
Department of Anatomy and Neurobiology
NEOMED
4209 State Route 44
Rootstown, OH 44272
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">On Jun 28, 2021, at 8:33 PM, n5pa <a class="moz-txt-link-rfc2396E" href="mailto:n5pa.dx.341@gmail.com"><n5pa.dx.341@gmail.com></a> wrote:
Tnx for the info David!
73,
Alan Clark, N5PA
Ellisville, MS
Email: <a class="moz-txt-link-abbreviated" href="mailto:n5pa@n5pa.com">n5pa@n5pa.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:n5pa@n5pa.com"><mailto:n5pa@n5pa.com></a>
URL: <a class="moz-txt-link-freetext" href="http://www.n5pa.com">http://www.n5pa.com</a> <a class="moz-txt-link-rfc2396E" href="http://www.n5pa.com/"><http://www.n5pa.com/></a>
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">On Jun 28, 2021, at 7:22 PM, David Waugh <a class="moz-txt-link-rfc2396E" href="mailto:dwaugh@kent.edu"><dwaugh@kent.edu></a> wrote:
?Alan, I?m new to the project and can?t answer your question. I think there was some theoretical limit for the cable length, but I can?t remember the number. My understanding with is that with a distributed network of sensors, local noise can be filtered out (or maybe in some cases corrected), so your lawn mower (and mine) will show up as a momentary spike and could either be ?smoothed" or cut from the dataset. I would assume some of this early data will help the end users (of the data) figure out what sorts of setups are usable, and come up with strategies to filter the data as needed. The more sensors available the more can be done, even if each sensor location has some occasional temporal issues. One can never have enough data, and data is never perfect. -David KE8QEP
David A. Waugh, Ph.D.
Research Assistant
Department of Anatomy and Neurobiology
NEOMED
4209 State Route 44
Rootstown, OH 44272
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">On Jun 28, 2021, at 7:16 PM, n5pa <<a class="moz-txt-link-abbreviated" href="mailto:n5pa.dx.341@gmail.com">n5pa.dx.341@gmail.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:n5pa.dx.341@gmail.com"><mailto:n5pa.dx.341@gmail.com></a>> wrote:
David:
Good info on the Magnetometer tests! I wonder what effect my zero turn mower would have running over it when it is buried or my heat pump running. What would be the maximum distance you can run the cable?
73,
Alan Clark, N5PA
Ellisville, MS
Email: <a class="moz-txt-link-abbreviated" href="mailto:n5pa@n5pa.com">n5pa@n5pa.com</a> <a class="moz-txt-link-rfc2396E" href="mailto:n5pa@n5pa.com"><mailto:n5pa@n5pa.com></a>
URL: <a class="moz-txt-link-freetext" href="http://www.n5pa.com">http://www.n5pa.com</a> <a class="moz-txt-link-rfc2396E" href="http://www.n5pa.com/"><http://www.n5pa.com/></a>
</pre>
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">On Jun 28, 2021, at 5:59 PM, David Waugh via TangerineSDR <<a class="moz-txt-link-abbreviated" href="mailto:tangerinesdr@lists.tapr.org">tangerinesdr@lists.tapr.org</a> <a class="moz-txt-link-rfc2396E" href="mailto:tangerinesdr@lists.tapr.org"><mailto:tangerinesdr@lists.tapr.org></a>> wrote:
?Tangerine list folks, with the help of Jules for suppling the boards (and help along the way), I was able to get the magnetometer running. Currently the magnetometer is buried about 2.5 feet in the ground under my deck. I have plans to to move it farther away from the house and driveways if needed. Attached is a short run (not perfect graphs) I made this morning with some notes about moving the cars around (purposefully to record the influence). The cars were parked maybe 30 feet from the magnetometer. Clearly they show up (moving the cars around), but it seems as if might be easy to correct, or recognize and ignore the disruptions. I can do some more tests, and a better ?write up? to try and come with a distance for which periodically moved parked cars show up in the data if people in the group think that might be useful. I?m excited about the project and look forward to collecting more data. I will post again once I have some longer runs, but if there is anything that I can e
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<pre class="moz-quote-pre" wrap=""> xamine, specifically, that would be helpful, please let me know. -David -KE8QEP
</pre>
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<blockquote type="cite">
<blockquote type="cite">
<blockquote type="cite">
<pre class="moz-quote-pre" wrap="">
<cars_moving_June_28.pdf>
David A. Waugh, Ph.D.
Research Assistant
Department of Anatomy and Neurobiology
NEOMED
4209 State Route 44
Rootstown, OH 44272
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