[aprssig] Flood Sensors (again)
steve at dimse.com
Mon Jun 13 15:20:14 CDT 2016
> On Jun 13, 2016, at 2:41 PM, Robert Bruninga via aprssig <aprssig at tapr.org> wrote:
> OK, how cheaply could we build highly reproducible APRS flood sensors?. [To keep idiots in SUV’s from thinking they can drive through it]
I'll leave the radio part to others, but the sensor is trivial
Less than $8. These need two IO pins, one triggers the reading, the second returns a pulse whose length is the time the sound took for two-way travel. Time the pulse, do the calculation. Any microcontroller works, Arduino library available.
There is a commercial device that was not very cheap called Flood Advisor that put everything in a nice PVC setup, a two inch PVC conduit pipe, open with copper screen (prevents organism growth and fouling) at bottom and a pinhole near the top; this gave a stable water level even in the presence of chop. The sensor went in the top cap, and then a junction box with the electronics on top with the antenna mounted to that. Ran for more than a year on a 6 volt lantern battery.
I have one in my canal but have not bothered to replace the battery for a few years because the APRS network died in the Keys so the data never went anywhere. At one point there were nearly a dozen on APRS, only two left now:
Using the same protocol means support already exists, the protocol included temp (in F), water level (-99.9 - +99.9 feet), and battery voltage.
K2GE-7>APFG21,K2GE-13*,WIDE2-1,qAR,N2MH-15:=4026.04N/07421.51Ww>T+079F-012V058 FloodAdvisor -81
findU also supports comparing the reports to tidal predictions, in this example the floodadvisor station is well upriver from the prediction point so there is a great deal of variance, but when it was set up at my house it worked well and did a good job illustrating wind effect on water level.
> Bob, Wb4aPR
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