Ultrasonic snow depth gauge

Really super, as says MikeyM, for my case it works correctly.
Serge

Here’s the latest graph being produced with GraphWeather. This is a graph of today’s current level of snowfall. Currently reading 26.6 - 26.7 inches under an indoor test setup. I’m still having problems getting the weekly, monthly and yearly graphs to display correctly, but with some help from the GraphWeather forum I hope to get those working also. At least we’re making progress and have gotten rid of the spikes that plagued eongibier and I last year.

http://home.ptd.net/~mikeym/graphsnow1.jpg

Cheers

:smiley:

MikeyM

Very nice. I hope it does well.

Mark

MikeyM,

Great project. I have worked to develop a system using the Senscomp Sensor and their 6500 Ranging module. You can see some details from our www.ohararp.com/blog.html

Recently a climatologist in Norway has asked us to add a Senscomp Ultrasonic Sensor and a simple temperature sensor to our SD GPS Data Logger to track snow depth measurement and glacial velocity movement on glaciers in the North Atlantic Region of the world. Using our skills we developed a quick prototype for initial testing at a fraction of the cost of traditional weather stations ($6K vs $400). We included a 10AH lithium ion battery and solar charging to boot! Let us know if you have a custom app that you would like us to look into! In the meantime enjoy the photos!

This was our intial version, but we are going to be adding some long range radio modules that are similar to the XBEE devices to your units. We then intend to serve this information to the ethernet with a simple serial to ethernet converter or possibly an FTP connection.

Some time ago (8/2008) I posted a long message about my attempts to use an ultrasonic sensor and a Basic Stamp programmable logic controller to build a snow depth sensor.

Much of it works fine. It is solar powered, using 2 12 volt panels to charge 2 alarm system batteries providing both 12 volt and 24 volt DC power. The sensor is a SensComp mini ae, and the output is an analog voltage (0-10VDC) which the analog-to-digital converter in the Stamp PLC converts. The data is then sent by radio modem to a nearby (indoor) PC where I can access it via FTP over the internet.

All the above works fine EXCEPT:

The SensComp sensor ( Mini-AE # 616100) works perfectly when presented with pieces of plywood at differing heights. All are reported correctly. When the snow started, it immediately reported 9.99 volts. In other words, it reports maximum range voltage, which I interpret to mean the echo from the snow surface is not being “heard” so the assumtion is it is beyond maximum range. There is a sensitivity adjustment on the sensor itself which is currently set to maximum. The sensor is about 8 feet from ground level, and the snow depth is currently about 2 feet.

I have visited one website for a somewhat similar system employing a senscomp Mini-AE and remarks there suggest that the sensitivity may be set too high.

see: http://voksenlia.net/met/snow.php

Does anyone have any experience with this sensor? Its very difficult to get to the sensitivity set screw on the sensor as mounted, and I was hoping to avoid doing this too many times if possible.

Thanks, Warpdrive

Hi Warpdrive

I’m using the Mini-AE # 616105 sensor which is the .5 - 20 ft sensor and I have the sensitivity set to about 2/3 or 66 % like Steinar suggested and mine has worked fine this Winter. I do get occasional spike in the data, but WD will filter them out.

Here’s the link to my snow depth sensor readings.

http://home.ptd.net/~mikeym/extrarealtimegraphmore.gif

And this is a link to a different graph. I need to incorporate some filter to eliminate the occasional spikes.

http://home.ptd.net/~mikeym/graphsnow1.jpg

Of course the spikes aren’t showing up today - go figure.

And yes it is a real pain to set the sensitivity once the unit is mounted. Good luck.

Cheers

:smiley:

MikeyM

Many Thanks MikeyM. I’ll give it a try. I am located in upstate NY, and we have about 26 inches on the ground right now.

Warpdrive

I am thinking of using a Mini-AE myself and tried to get SensComp to send me a quote for shipping to Canada. They couldn’t tell me how much it would cost and whether they can use UPS standard or express, until I put an order in. :?

mikeym, when you say occasional spikes, is that like several times a day? Also, from what I have read, the sensor does not reliably report depths until there is a build up of snow that’s at least several inches from the base?

Yes, I’d say occasional spike - some days none and other days quite a few. Brian has WD filtering the data so that rarely a spike will show up in the WD extra sensor graph. The GraphWeather graphing program that I’m using doesn’t have any filtering so that’s where my occasional spikes show up. I haven’t had time to go out and tweak the sensitivity setting and that might fix the problem. So far this Winter it has been very reliable and I’m happy with the performance. The Sensor that I’m using measure from .5 feet to 20 feet, but sensor allows the max and min distance to be set at either the high (5 volts ) or low (0 volts ). I have my sensor set up for 50 inches so 0 volts is no snow and and 5 volts is 50 inches. With this setup the sensor will start sensing the snow almost immediately. With that said it does depend on the density of the snow. Very light fluffy snow is much harder for the sensor to detect that heavy wet snow. I would say that dry fluffy snow will take a couple of tenths before it starts to get reported. Hope that helps. I also think that the spikes are a 1-wire problem and not a Senscomp sensor problem. I haven’t had time to hook an oscilloscope up and monitor the line. Like friend told me “I’m so busy since I retired that I don’t know how I found time to go to work”. Guess I’m just good at wasting time.

Cheers

:smiley:

MikeyM

I have a silly question: how do you connect your non standard sensors to a VantagePro, i.e. what inputs are you using?
I couldn’t find any spec about the input signal.
E.g. the leaf wetness sensor or ground temperature sensor inputs: are they 4…20mA, or 0…10V or what?
How do you calibrate and convert? Externally in your weatherstation software?

Before even thinking about a solution for snow height measurement I’d like to get a better understanding about how to interface and input/convert the data.

And then I might try some of your suggestions or others (like something based on laser distance metering)

Thanks
Hans

Hans

The snow sensor is interfaced to WD using 1-wire. Basically the analog output from the ultrasonic sensor is applied to the Vad input of a HobbyBoards humidity board minus the humidity sensor and the the signal is fed to a 1-wire adapter that can either be a serial (RS232) adapter or a USB 1-wire adapter then WD will read the input. There is no interface or anything connected to the Davis Vantage Pro.

Hope that helps.

Cheers

:smiley:

MikeyM

Just a quick question… Is this system available in kit form for sale and if so how much is it? I would be interested in possibly obtaining this if it works well with a Lacrosse WS2310 setup.

Mike,
now that I searched a bit in the forum I understand what hobbyboard, WD, WDL and 1-wire means…
I do not use WD but Davis’ standard software (Weatherlink) and a German program (Wetterstation).
My intention is, do connect/interface some kind of sensor to the remote sensor units I’m already using. There are available inputs (e.g. leaf wetness sensor, ground temperature, …).
But I do not know the specification of that (non serial, non 1-wire) analog interface.
I hoped somebody could help me and did something similar already.

Thanks for the feed back anyhow; helped me to learn something new :wink:
Regards
Hans

http://www.hsn.de/my-weather/WS-Win/start.html

Hi John

No this is not available in a kit. You have to round up the parts and put it together yourself. The best source of info is Steinar’s site in Norway. Here’s the link: http://voksenlia.net/met/snow.php
Basically the sensor is from Senscomp and the board is the temp/humidity board from HobbyBoards minus the humidity sensor. Eric is more than happy to supply the board minus the humidity sensor.
Hope that helps.

Cheers

:smiley:

MikeyM

Hello,
(Sorry for my English, it is about a translator)

Like MikeyM, from time to time but really seldom of the discharges on my graph. But that functions correctly.

Good day
Serge

MikeyM;

Thanks for the info. Any idea of a ball park cost for the required parts?

Hi John

Here’s the link to Senscomp and you can request prices from them. I think the last one I bought was $78.50. All total you’re probably looking at about $150.

http://www.senscomp.com/

Here’s the link to the Hobbyboards interface. http://www.hobby-boards.com/catalog/product_info.php?cPath=22&products_id=46
With that said the interface board is less than that because the humidity sensor is not used. You’ll have to email Eric for a quote on that.

You’ll also need the 1-wire adapter. A Google search should find that for you. Here’s a couple of links that I found.
http://thediysite.com/index.php?main_page=product_info&products_id=11&zenid=768a3160748a2b23dc4b9f59dfa66ee5
http://pachicount.tammarproducts.com/Products/Serial_Order.htm
http://www.maxim-ic.com/products/ibutton/products/1wire_adapters.cfm
http://www.aagelectronica.com/aag/index.html?target=p_33.html&lang=en-us

Cheers

:smiley:

MikeyM

I’m back with more information about my misfiring depth gauge.

As you might have found in my prior posts, I am using a SensComp Mini-AE sensor reporting to a BasiStamp PLC with A/D converter. This then radios results to a PC that allows me access via FTP to the results.

The problem has been: The SensComp Min-AE is producing a 10 volt signal regardless of distance to target. Adjusting the sensitivity doesn’t seem to alter that.

Facts relating to this:

The Mini-AE is mounted approximately 8 feet above the earth’s surface. On the ground directly under it is a white 4x4 foot sheet of plywood. The Mini-AE is mounted in a Davis weather instruments pagoda and mounted on a 3 foot arm from a pole. The area around it is fenced so that an area of snow more than 4 x4 feet directly below the sensor is undisturbed.

The Mini-AE has been leveled in all directions with a spirit level. The reflective surface on the ground has been leveled with a spirit level.

The snow is now 2 feet deep and has a hard crusty smooth surface. It is level as well. Approximate distance from the snow surface to the sensor is 6 feet.

No attempt was made to use the zero setting switches on the Mini-AE. It is a model #616105 which is powered by batteries and a solar charger producing 24 volts and the sensor produces a 0 - 10 VDC analog signal proportional to distance - 0 volts at 6 inches from the sensor (7.5 feet of snow), +10 VDC at 20 feet from the sensor. Of course with no snow on the ground, the sensor is about 8 feet from the ground, so the 10 volt depth signal voltage should never be seen.

Depth calculations are done by the Basic Stamp PLC based on the analog signal voltage and operator entered constants for sensor distance from bare gound.

The system was set up during the summer and worked perfectly on hard “targets.” The sensor would correctly read the distance to the plywood target base, and would read correctly the height of a stack of cardboard cartons used to simulate surfaces of varying heights.

Current state:
There is about two feet of very firm crusty snow with a smooth level surface under the sensor.
I just concluded some adjustment test in which I adjusted the sensitvity of the Min-AE as follows:
adjustment potentiometer position desired sensitivity my result
fully counterclockwise minimum 10 VDC
mid range mid range 10 VDC
fully clockwise maximum 10 VDC
These voltages were measured with a VOM at the connection to the Stamp PLC, so the bad readins are definitely the result of a high sensor reading, not a PLC software issue. When the sensor is powered off, the signal voltage is 0 VDC according to the VOM (normal expected result).

Discussion:

I don’t know what 10 VDC “means.” Obviously it means that the target is at or beyond 20 feet, but clearly that’s not the case here. Does it also mean the sensor is confused by false readings produced by a too sensitive setting? Could the sensor have gone bad? The bad signals began at the moment we received our first snowfall. The ground has not been bare since.

Hey - maybe I could test this simply by putting a “hard target” on top of the snow, like a piece of plywood! It should read correctly if the sneor is good, given it could do exactly that in September.

Thanks for any suggestions

Warpdrive

That is exactly what I would suggest. A question, have you measured the 10 volts directly? Or is that just what the BS is telling you it is?

Thanks Niko

I did measure the 10 VDC signal voltage from the Mini_AE directly using a VOM just so I could be sure there is no PLC software confusion. In each case, changing the setting of the gain potentiometer had no effect on the VOM reading - it was always 10 VDC.

A problem for me is that to change the setting I have to disassemble and reassemble the SensComp blue box inside a weather instrument pagoda, make an adjustment, then reassemble and align using a spirit level, all the while perched on a ladder in 25 degree weather trying not to disturb the snow on the target below or drop parts. Each adjustment requires about 15 - 20 minutes. So I only did a “min”, “middle”, and “max” gain test.

Somewhat off topic but curious - when I was in graduate school, I discovered while taking a computer simulation course that the best way for me to correct programming errors was not to sit in front of a terminal pounding keys, but rather to write a statement about the program and perhaps why it was going wrong. Inevitably I found the error, but only when I was NOT at the terminal, but writing a statement about the problem in English. Sure enough, while writing the last post to the group, I came up with a simple test which might at least verify the functioning of the sensor. We all have different ways to get to solving problems. Thanks for bearing with me.

But I am still curious what 10 VDC means. The SensComp literature is not much help, other than 10 VDC should equate to maximum distance, and “Excessive gain may result in false target detection.”

Warpdrive