[aprssig] Flood Sensors (again)

[Steve Dimse]

> 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

http://www.ebay.com/itm/Ultrasonic-Module-Distance-Measuring-Transducer-Sensor-Waterproof-/381374561353?hash=item58cbb1fc49:g:GvcAAOSw6BtVUbL4

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:

http://www.findu.com/cgi-bin/floodadvisor.cgi

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. 

http://www.findu.com/cgi-bin/water-list.cgi?call=k2ge-7&tide=705&floodoffset=5.5

Steve K4HG


> Bob, Wb4aPR
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