[aprssig] Flood Sensors (again)
Brian D Heaton
ky9k-lists at ky9k.org
Mon Jun 13 20:24:47 EDT 2016
It seems easy enough to replicate the sensor side using the ultrasonic
sensor or small float switch inside a piece of PVC.
If buying radios new, something like a Friendcom FC-301 and j-pole
encased in PVC would do the trick on the radio side. If going used, any
number of surplus HTs fit the bill. The electronics/TNC package should
probably keep the radio powered down except when it comes up to transmit
status. A dual-profile TNC/tracker setup that beaconed a very few times
a day with no flood and that flipped to a second profile and beaconed
more rapidly when flooding is detected would seem to accomplish the
mission well. Power could come from a small battery charged by the size
of solar panel usually used for automatic gate openers.
Perhaps local ham groups could assemble units from a specified design or
kits and then "adopt" several low water crossings in their area. The two
biggest problems would likely be the government interaction for
permission to install and damage due to vandalism.
On 6/13/2016 13:20, Steve Dimse via aprssig wrote:
>> 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.
> Steve K4HG
>> Bob, Wb4aPR
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