Depth finder transducer

jeffjohnvol

I have a dock on a lake that the water drops during the winter, and sometimes I have to move it.· I was thinking about setting up a PINK or Simple Lan to be able to track if the dock needs to be moved or not.

I know I can get sonar transducers, or digital depthfinders.· Has anyone successfully interfaced one of these devices to a Propeller or a Stamp?

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MSDTech

If you can mount a transducer in a fixed location to monitor the water level, that should give you the same information. Although the PINK is not water proof, it can be protected and used to monitor the waterline. The following link describes using an ultrasonic transducer to monitor the freeboard on a vessel.
http://www.cocoontech.com/index.php?showtopic=4419

jeffjohnvol

The water level fluctuates as much as 25 feet and the dock floats (no fixed piers or anything) so the transducer might be hard to do.· I can check the water level· from the TVA website, but sometimes when it is close to the "move time" the water can drop a few feet a day, so I thought a fun project would be to have a system send me an email daily or an alert if it gets too close.

Also, each year when the water is down, I try to dig down and remove rocks to get my dock more clearance, but when the water fills up in the spring, silt and shale fills up (the picture is my last digging effort).· So it would nice to have an actual measurement rather than checking the lake level each day.· When I dug it out last time the dock was moved away from its normal position.· I wasn't even sure if I dug back far enough (toward the shore).· A depth finder alert would help me with that.



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kelvin james

I would tend to think a sonar unit with a serial output to be a little costly. What about a float switch device?

jeffjohnvol

Its more of an intellectual exercise at this point, I don't know if I will go through with it, I was more curious if it was possible (of course,·anything is possible [noparse]:)[/noparse] ). I wasn't sure if a sonar transducer would have an analog output and if so, it would perfect for a $20 zigbee.

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Post Edited (jeffjohnvol) : 7/21/2008 1:42:24 PM GMT

Phil Pilgrim (PhiPi)

Digital depth finders comprise a market where consumer electronics rule in price and performance. For example, the Garmin Intelliducer is a no-frills, compact unit with an NMEA 0183 output. NMEA 0183 is a serial protocol, like RS232, which is easy to interface to a micro. From there, you can do whatever you want with the depth data.

-Phil

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jeffjohnvol

Thanks Phil.·

I wonder if it would be possible though to hack one of these:· http://www.amazon.com/Uniden-QT-206WHP-Digital-Adjustable-Transducer/dp/B0000AXS0G.·

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Phil Pilgrim (PhiPi)

It doesn't have an NMEA interface, so you'd have to dig into the guts to isolate the ping and echo pulses and bring them out. It's not the cleanest solution and may violate the gauge's watertight integrity.

-Phil

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Searider

I live near a non-constant level lake that goes up and down throughout the year. There are people who make a living at adjusting docks as needed. Does your dock use a couple of anchors and wenches to move it out and back as the water level changes? If so you could posibly control the wenches with the propeller based on the depth finding. This would make it a fully automatic system.· Another approach besides a sonor would be to use a physical depth test. This could be as simple as a PVC pipe that goes down a foot or two below the shallow end of the Dock. When it hits ground it closes a swith at the top (out of the water) and tells you that it is time to move the dock.··

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Searider

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jeffjohnvol

Right now the bridge is attached to the shore on a concrete block and there are cables that hold the corners (see attached when water is high).· The corners have manual winches to tighten/loosen the cables.· When it drops, I have to pay to have it detached and a guy (not a wench [noparse]:)[/noparse]) moves it down to the shore with the help of about 3 other guys.· I'm building a ramp so that the base of the "swivol-pivot" bridge can be lowered by myself.· I don't want to automate it though, given the risk of getting some one's foot caught or not knowing what may be in the way.

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StarMan

An accelerometer on that bridge can sense an angle of incline.· Then use a little trig to figure the drop in water level.

Chris I.

jeffjohnvol

When the dock gets waked, it rocks side to side (and front to back), and the bridge is hinged so it swings up and down (maybe a foot or less). On average that would probably give a decent value (throw out the high/low). Its not a bad thought, but it would be best if I could get the depth finder working. That way, it would tell me how much room I have underneath the dock no matter what position it is in (sometimes I have to lower the base to the shore, pushing the dock out 15 feet, and sometimes have to move it further). If a large log sinks underneath it would tell me, or if a big rock slid down. Of course I would need one for each corner of the shore side (the lake side is 15 feet deeper due to the rapidly sloping lake bottom).

I was hoping there was a way to take a $100 depthfinder, cut the transducer wire and figure out out to issue a pulse and read to get a value. I understand the principal the way the parallax unit works, I was hoping i could do something similar with a sonar transducer I could buy or even cut off of of a boat in a junkyard.

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Post Edited (jeffjohnvol) : 7/24/2008 7:10:04 PM GMT

Phil Pilgrim (PhiPi)

You'd be better off keeping the electronics, too, and hacking into them for the signals you need, so you don't have to redesign and build your own transducer driver/receiver. The latter would be a difficult and unnecessary undertaking.

-Phil

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SRLM

What about using some shore based solution? From your pictures, it looks like you have a stable platform nearby. If you were to put a BS2 on the porch and one on the dock, you could measure the difference in the distance between them to find how low your dock is. If this doesn't work, consider a gyroscope. Unlike the accelerometer, it is much less affected by a wave or a log, and can more accurately tell you if the dock is tilted.