River water level

[B J]

WATER HEIGHT ?   ---   Looking at using an ultrasonic system  (WINGONEER DC 5V Waterproof Ultrasonic Distance Sensor system  ) and mounting the sensor on a post overlooking the river.  I will use the waterproof sensor.  Take the echo return time signal and use it to start and stop a counter.  (Digiten 4 digit LED counter panel meter.  )   Looking at the LTC6900 to create about a 5.6 KC  time base for measuring the distance in feet.  ---   A couple questions:  Can I extend the cable between the control module and the sensor to 250 feet?  If so can I use multi conductor cable, or would the sensor need to have coax?  What kind of stability is reasonable to expect using these parts and overall method?     Any thoughts and/or other ideas?  How about a better way?    Comments ?  –  Thanks

[NivagSwerdna]

 :box:I've been considering measuring the water level in a tank and thinking about a similar approach... I was thinking about putting the sensor at a top of a bit of pipe, vented at the top, so that the sensor is only measuring inside the pipe.
I was going to use either RFM69W or WiFi to get the readings back.

How often do you want to take readings?

PS
If wired maybe RS485?  I am not familiar with 4-20mA but it is possible that there might be an off the shelf solution in that arena?

[B J]

Thanks for the come back.  I was going to use wireless, but the water is over a high bank and would be rough to get line of site for low power RF.  If I can put the sensor on 250 feet of wire, great.  Also if that doesn't work, I will put the controller down at the river and just send the timing pulse back up the hill.  I don't think getting a wire from the river to the house will be to bad.      ( I know, but sometimes old tech is still the best.  )

[jmelson]

Can I extend the cable between the control module and the sensor to 250 feet?

Without any other considerations, if you have lightning strike within 1000 feet, it will likely damage the equipment at both ends of the cable.  Lightning produces an intense electromagnetic wave, and especially any long wires parallel to the lightning bolt will pick up hundreds of Volts.  I've had lots of stuff blown out around here such as Ethernet interfaces and various computer and home alarm system parts, all related to long runs of wire.

So, just a suggestion to think about.

Jon

[soldar]

  Comments ?  –  Thanks

What range are you trying to measure?  I doubt that sensor would work well in the open and against water. Maybe if you build a solid well and have a flat floating surface which would reflect good echo.

Depending on the range and location there may be other solutions.What are you trying to control with this?

[badman]

Could use optical cable. For wireless I guess LoRa?

[Etesla]

Ultrasonic sensors will work with reasonable accuracy with water as the target (+- 1 inch, probably within the motion of the waves in the water anyways). Having a data line, and more notably a power cable that long IS an issue. The edges of the pulse the sensor sends back need to be sharp (a slow rising edge would shorten the recorded time for example). Also, noise could be an issue with cables that long.
The bigger issue, however, is with power. Those ultrasonic sensors draw upwards of 2 amps when they take a measurement. Because of this, the resistance between the power supply and the sensor must be minimized. To solve this, a 'huge' decoupling capacitor (probably hundreds of micro farads with smaller caps in parallel) could be used near the sensor, and it would have to not sample too often. If you want to improve the signal integrity, and solve the power issue, it might be smart to have a separate power supply at the sensor, as well as a second microcontroller. This microcontroller would control and read the sensor, and communicate with the original microcontroller either wirelessly, or with a UART or something.

[B J]

Sodar, the range will be between eight and two feet.

[B J]

Etesla, the duty factor is very low.  Several seconds, if not even minutes.  River level changes very slowly.  Plan on putting a regulator at the control module.  The unit I am looking at puts out eight pulses at 40 KC.    Very low average power required.

 

[ptricks]

I live in an area on the east coast that has lots of rivers and they have quite a few water level sensors deployed  and they appear to use solar to charge batteries then relay the data using lower frequencies which lets them send it long ways through trees, etc. I'm not sure of what radios are used but the antennas look like something for sub 1Ghz band.  I don't know about lightning risks , etc but they don't appear grounded other than just to the pole they are mounted on at bridges. 

I would probably do solar then send the signal back using a 900Mhz radio since the range is going to better than wifi. 
Another option if you want to do wired is the maxim one wire line of products. One wire, really two wires, lets you run power+data on one wire and another wire for ground and put sensors anywhere along those two wires and 250 feet is not an issue, it is also cheap to implement.

[Neomys Sapiens]

Those people seem to know a lot about it, especially metering of flow in open, irregularely shaped channels:

https://www.usbr.gov/tsc/techreferences/mands/wmm/index.htm

[Stray Electron]

  You might want to read this also. http://www.itrc.org/reports/pdf/sensorsummary.pdf

[B J]

Thanks for all the feedback you've sent.   –  I have been experimenting with the Wingoneer and just not satisfied with it.  The echo time pulse output seems to get confused very easily and is not consistent.  It does a good job of putting out the pulse, but I am now looking at making my own receiver.  I have  a Murato MA40A35 which does a fair job of picking up the echo.  On the shorter distances, great, but on the longer distance, not quite.  The signal is down in the noise too far.  This device is peaked at 50 KC so my question is, can it be tuned to a lower frequency?  ( 40 KC )   Any one try this?    ---   How about another mic that is peaked at 40KC?   I want to stay away from the large expensive microphones.       Anybody know anything about the SiSonic Spu0410LR5H-QB ?   Looks good on paper but have not had a chance to check it out.    ---   At this time I am just working on getting the data.  Once I have it I will see about getting it up out of the canyon to the shop.  There are several workable ways to do this, I hope.

[mkschreder]

Not wifi, but LoRa may be what you are looking for.

Sent from my SM-G960F using Tapatalk

[MarkF]

Here is a nice comparison of RF modules.

   

[coppercone2]

keep in mind the old ways, where you put a stick with a rule on it into the water. You can have a camera just take pictures of it.

Kind of fool proof

question being, what is your calibration procedure on sensors? A stick you can just look at. You would need to go out there once in a while and measure it manually to compare. And for official data gathering you might need to know effects of temperature and humidity on your sensors, and the effects of age, wheras a stick stays pretty convincing so long it does not sink.

I.e. you need to know that in 5 years time your sensor won't suddenly start giving incorrect readings at night when humidity is high or something like that. If your data is for someone important i.e. weather studies/global warming related etc, or a game commission for fishing. Sounds like the type of data that might end up in court one day.

[todd_fuller]

You may want to check out envirodiy.org. They’re doing exactly what you want. Lots of good information on sensors, communications, stilling wells, etc to read stream levels.

[Sparky49]

Sorry, I have little to offer other than it reminded me of this thread from a short while ago which may have some useful info for you:

https://www.eevblog.com/forum/chat/measuring-river-depth-water-level-and-flow-speed-(houszxcty-flooded)/msg2300583/#msg2300583

All the best.

[B J]

RE:    (WINGONEER DC 5V Waterproof Ultrasonic Distance Sensor system  )           I have one and it is looking very good.  Had to give it a little extra time and help, but now appears to be very solid.    Wondering if anyone may know what the adjustment on the board is for?      Is it critical or can I play with it without messing it up?  If I know what it is for, would be a great help.

[Gregg]

How about an aquarium air pump, a pressure transducer and a small tube to the bottom of the water.  The pressure is directly proportional to the depth of the water.  The pump and transducer can be located wherever convenient to power and the whole setup is quite foolproof.   

[langwadt]

How about an aquarium air pump, a pressure transducer and a small tube to the bottom of the water.  The pressure is directly proportional to the depth of the water.  The pump and transducer can be located wherever convenient to power and the whole setup is quite foolproof.   

just use a differential pressure transducer, one side to atmosphere other to bottom of water

[max_torque]

How about an aquarium air pump, a pressure transducer and a small tube to the bottom of the water.  The pressure is directly proportional to the depth of the water.  The pump and transducer can be located wherever convenient to power and the whole setup is quite foolproof.   

just use a differential pressure transducer, one side to atmosphere other to bottom of water

The pumped system does have the advantage that it clears any blockages in the pipework or entry point, although the diff pressure could be easily achieved via some form of "hydraulic" transfer, ie, a silicon / mineral oil filled "void" around the pressure sensor, with some form of flexible diaphragm separating the water and oil, so that oil transfers the pressure straight to the sensor! 

[Rerouter]

The river level sensors used in rural areas of australia use a piezoelectric resonator connected to a finger of metal, the more water pressure, the more resistance to the vibration, and you measure the frequency output to know your pressure,

They tend to be oscillating in the 44-150Hz range to keep power low, but swing things up with a high power ultrasonic driver every few days as a cleaning cycle.