[TangerineSDR] may have spoken too soon

[Julius Madey]

re_previous 'problem' report:
Further testing confirmed problem due to voltage sag at end of CAT5 
cable; in retrospect, a 'classic' example .... oops.

I did not take time to measure dropout voltage on this unit before 
installation as I did on the first board used in a weather proof above 
ground box install.  Changing to an SPX1117M3-L-3-3 LDO regulator with 
250mV additional dropout margin as well as larger filter caps.

 From a voltage drop viewpoint, 400 feet of CAT5 or CAT6 24Ga solid 
copper wire and a well regulated 5 volt supply for the microcomputer 
represents about the practical limit in cable length.  Standard  i2c 
signalling rate of 100KHz presents no problem at that length.

Jules Madey K2KGJ

On 8/12/2020 3:14 PM, David Witten wrote:
> Jules,
>
> Very interesting!
>
> I'm curious what effect we might see burying the sensor completely, 
> say below the frostline:
>
> Frostline Map <https://www.hammerpedia.com/frost-line-map/>
>
> This would make deployment more difficult, but would surely provide 
> significant stability.
>
> But what does it do to magnetic field lines?  - one more experiment 
> that I would like to try sometime: place several sensors in a vertical 
> column at, say 500 cm intervals in a fairly uniform deposit of soil.
>
> Seismic interaction is something I hadn't considered.
>
> Dave
>
>
> On Wed, Aug 12, 2020 at 1:21 PM Julius Madey <hillfox at fairpoint.net 
> <mailto:hillfox at fairpoint.net>> wrote:
>
>     Dave,
>     Did a 13 hour run from 2300edt yesterday to noon today and then
>     started a second run to complete 24 hours.  Seeing a slight 0.3
>     degree upward shift in temp over the 13 hours. The sensor results
>     are not flat line and still show some drift with an initial
>     relatively rapid change after starting the run ... have to see if
>     the same thing happens on the run in progress now.
>     Some activity around 0400edt to 0900edt which I can't explain as
>     magnetic field shifts, at least according to the data from
>     Intermag.  Might be seismic activity related as any movement of
>     the sensor could also create a 'signal' in the low nT range  (~50nT).
>     Jules
>
>
>     On 8/12/2020 10:26 AM, David Witten wrote:
>>     Jules,
>>
>>     I will look closely at this when I get back from my appointment
>>     this am.  THere are definitely some untested 'features' here.
>>
>>     Dave
>>
>>     On Tue, Aug 11, 2020 at 9:49 PM Julius Madey
>>     <hillfox at fairpoint.net <mailto:hillfox at fairpoint.net>> wrote:
>>
>>         Dave,
>>         I think we're OK   operator error here with parameter formats
>>         ....
>>         Sorry for the false alarm
>>         Jules
>>
>

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