[engolling]

Thank you for your interest.
During the last years - unfortunately winter and snow is only at a limited period I tried to get a working snow depth measurement.

1. "Optical measurement" with an array of photo diodes. 
   My first try was to bulid an vertically aligned array of photo diodes in order to get an changement of the brightness when under snow. The test device was 1m high with 50 diodes every 2cm. Because I did not get suitable readings i added an array of IR LEDs in a distance of about 2m to illuminate the diodes.I'm still thinking this should have worked, but it's now about 5 years ago. Maybe I made some other mistake in multiplexing the diodes...
   So, first try: failed
   
   
2. Optical measurement with a scale like a flood marker, every 2cm black and white marks.
   I built a scale and pointed with a (IR) camera on it to make a picture in order to analyze it with a python script. Here I faced the problem with different gray scales during day and night. Since I am not as deep in image processing than in hardware I didn't it get to work properly...
   Second try: failed
   
   
3. Ultrasonic measurement. I built a ultrasonic measurement device in a case and set it up on my own built station.
   Mounted in 150cm height it generated a noise between -4cm and 24cm shown height. Lowered to about 100cm height the noise lowered to about 5cm. Left outside at the Station I soon got wrong readings maybe due to rain or wetness. The electronic part even was mounted in a water proof housing but the ultrasonic Generator and Receiver necessarily were exposed to the environment.
    At some Point I did not get any longer (wrong) readings. I think the sensor has been destroyed due to environmental influence.Third try: failed
   
   
   
4. So I did some investigation how weather services do a snow height measurement and I found out that it is done by a laser ranging system. With this knowledge I searched a supplier of commercial laser ranging systemes, used for example at construction sites. Here I found the company were I could sample a device which allowes to be read over a serial Interface. The supplier even gave me the comunication protocol and all information I needed to read it with my arduino. Mounted in a waterproof housing I can achieve very precise readings (see pictures).
   
   
   
   
   

I still have a quotation from the supplier, but I would have to take 100pcs which cost about 20 EUR per Piece including VAT.
So if there is a huge demand we could think of a collective order, but I don't want to have 100 laser ranging devices liying at home. 


Since I'm tired in working and debugging alone in my weather station software I'm planning to switch to WeatherDuino and to contribute with some sensor development.