[aprssig] water level gauge for APRS
steve at dimse.com
Tue Aug 16 19:02:58 EDT 2016
I think you will have much more interest from FEMA and other Emergency Managers if you offer water level readings, not just FLOOD/OK. And really, if you are going to this much effort, there is not much reason not to do this. An ultrasonic sensor is not more expensive than a float switch.
Just today I ordered a new PIC, the first of the new PIC32MM line. An interesting mix of the PIC32 core with 16F style peripherals. It is optimized for low power with built in RTCC, sips a few microamps sleeping with the clock running. Easy to set the RTCC to wake up the computer at whatever interval you want. With that you can leave it on all the time, just power up any old HH radio thru a MosFET. Probably get the DAC to handle the output if you didn't want to spend the money for an MX-604. Way cheaper than what you propose.
If you want to go a more hobbyist way and avoid PICs and low-power mode, use one float switch to turn on everything and an arduino, it would take an hour to graft the ultrasonic code onto the AX-25 code that is already out there.
But whatever you do, don't waste time and money with an FLOOD/OK two state kludge.
> On Aug 16, 2016, at 5:19 PM, Robert Bruninga via aprssig <aprssig at tapr.org> wrote:
> Revisiting the Flood gauge for APRS idea... due to some interest at FEMA
> I found some sealed float switches $10 that will fit along with 4 D cells
> and a 2 Watt Tinytracker from Byonics in a 1.5" PVC pipe.
> We use two switches, the first one just above normal water to turn the
> thing on, and then the second switch at a level that changes the beacon
> from GAUGE ACTIVTED to FLOOD ALLERT or something like that. It is
> tempting to include actual height, once it is on, but this two swtich idea
> is a starting point.
> Will also include a magnetic microswitch so that it can be tested by
> holding a magnet to the right spot on the outside. Batteries should last
> a year or more, since they are never on except during flood events.
> If we can get FEMA to buy a bunch of switches and other parts, how many
> people might invest $X to complete them? The Microtrack is going to be
> probably in the $150 to $250 range, and I doubt I can get FMEA to buy them
> in bulk. Though, that is going to be my going in position...
> (Or any other TRACKER product on the market that will fit in a PVC pipe
> and have at least two configuration beacons that are switch selectable.
> Bob, WB4aPR
> -----Original Message-----
> From: Steve Dimse [mailto:steve at dimse.com]
> Sent: Sunday, October 04, 2015 11:54 PM
> To: Robert Bruninga; TAPR APRS Mailing List
> Subject: Re: [aprssig] water level gauge for APRS
> On Oct 4, 2015, at 8:03 PM, Robert Bruninga via aprssig <aprssig at tapr.org>
>> TO make a flood gage, it would seem that a simply pressure sensor like
> we use for atomosphere for balloon payloads would work.
>> Just put it inside a pipe with a cap on the top and open on the bottom.
> Then the pressure will vary with the height of the water. Connect this to
> the analog input of an APRS tracker and you have a flood gage. Calibate
> it with some testing and done...
> you'd have to worry about temperature, and the chamber would have to be
> perfectly and permanently sealed. There is an easier way.
> It never got much traction, but there is a commercial product
> that is apparently still for sale, and includes integrated TNC and radio,
> runs for a year on a lantern battery. Their non-ham product uses satellite
> reporting. At this time there are just two stations still using the ham
> version, you can see the data at
> I have one at my house, but never did replace the battery when it died.
> This uses an ultrasonic sensor that measures the water level inside a PVC
> pipe, open (copper screen) at the bottom and with a tiny vent hole at the
> top. I don't know what sensor it uses, but in other projects I've used
> this sensor with good results,
> send it a 5v trigger signal, and get back a pulse whose length is
> proportional to distance, easy to measure with a pic or arduino. There is
> a non-waterproof version for less than $2 for inside use too.
> If you develop something, please consider sending with the flood advisor
> protocol so it is parsed by findU, then you will have graphing available
> for no extra effort.
> 030V062 FloodAdvisor -30
> the data is temp, height*10, voltage*10, and at the end an optional
> sequence number.
> Steve K4HG
> aprssig mailing list
> aprssig at tapr.org
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