[TangerineSDR] EXT: Re: Magnetometer tests

Wed Jun 30 18:17:09 EDT 2021

David, et al,  the values from Dave Witten's software are in microteslas 
so 46.9 to 47.1 uT is a 200nT jump, quite large in comparison to what 
may be no more than +/- 20nT diurnal variation in the absence of 
signficant geomagnetic activity.

I believe you need to interchange your Z and X values (as read from the 
software which assumes the RM3100 PC board is horizontal with connector 
pins pointing down and the white arrow in the left corner of the board 
indicating the magnetic North direction.

But, even considering the large magnitude of those signals, they are 
pretty clearly man made and could relatively easily be removed from the 
data stream.

Regards,
Jules

On 6/30/2021 5:59 PM, David Waugh wrote:
> 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
>
>> On Jun 28, 2021, at 8:33 PM, n5pa <n5pa.dx.341 at gmail.com 
>> <mailto:n5pa.dx.341 at gmail.com>> wrote:
>>
>> Tnx for the info David!
>>
>> /*73,*/
>> /Alan Clark, N5PA
>> /Ellisville, MS
>> Email: n5pa at n5pa.com <mailto:n5pa at n5pa.com>
>> URL: http://www.n5pa.com <http://www.n5pa.com/>
>>
>>> On Jun 28, 2021, at 7:22 PM, David Waugh <dwaugh at kent.edu 
>>> <mailto:dwaugh at kent.edu>> 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
>>>
>>>> On Jun 28, 2021, at 7:16 PM, n5pa <n5pa.dx.341 at gmail.com 
>>>> <mailto:n5pa.dx.341 at gmail.com>> 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: n5pa at n5pa.com <mailto:n5pa at n5pa.com>
>>>> URL: http://www.n5pa.com <http://www.n5pa.com/>
>>>>
>>>>> On Jun 28, 2021, at 5:59 PM, David Waugh via TangerineSDR 
>>>>> <tangerinesdr at lists.tapr.org <mailto:tangerinesdr at lists.tapr.org>> 
>>>>> 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 examine, specifically, 
>>>>> that would be helpful, please let me know. -David -KE8QEP
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> <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
>>>>>
>>>>> -- 
>>>>> TangerineSDR mailing list
>>>>> TangerineSDR at lists.tapr.org <mailto:TangerineSDR at lists.tapr.org>
>>>>> http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org 
>>>>> <http://lists.tapr.org/mailman/listinfo/tangerinesdr_lists.tapr.org>
>>>>
>>>> *CAUTION: *EXTERNAL SENDER**Do not click any links, open any 
>>>> attachments, or REPLY to the message unless you trust the sender 
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>>>>
>>>
>

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