Hi,
I'm planning to build a simple ceilometer
the ideia is to measure the time of flight between a laser and the clouds, reading its backscatter
the distance of measure should be between 100 and 5000 feet , with a low accuracy, around 20 feet
what type of sensor should I use to detect backscatter? LDR Photoresistor?
I think
LDRs are impossibly slow and insensitive for such an application. PIN diodes and APDs (avalanche photodiodes) are fast, and are commonly used to detect weak light signals.
Hint: there is nothing simple about your project.
jremington:
Hint: there is nothing simple about your project.
Sure it is. You send a pulse to an IR emitter and time the reflected pulse. I think the biggest problem will be the speed of an Arduino being too slow to get good results.
Hi,
Have you googled
ceilometer arduino
Tom... 
TomGeorge:
Hi,
Have you googled ceilometer arduino
Tom...
Hi Tom, yes, nothing like that on the internet
LDRs are impossibly slow and insensitive for such an application. PIN diodes and APDs (avalanche photodiodes) are fast, and are commonly used to detect weak light signals.
jremington, ive spoke with a friend that provides support to a real ceilometer and he told me that it uses a 905nm IR laser and a 905nm photodiode with a 905nm filter.
I dont think ill be able to build this with a simple arduino =(
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maybe a Infrared Thermometer - MLX90614 to measure the sky temperature and then calculate the distance?
MLX90614 to measure the sky temperature and then calculate the distance
That is an easy experiment to try! It is trivial to determine whether there is cloud cover or not, using that technique, but see if you can find a relationship between temperature and distance to cloud cover.
Please ask your friend about the power output of the IR laser used in the ceilometer. I would be very interested to know.
jremington:
Please ask your friend about the power output of the IR laser used in the ceilometer. I would be very interested to know.
He told me that is a 19W IR 905nm laser!
rgusso:
He told me that is a 19W IR 905nm laser!
Doesn't that just punch holes in the clouds?
TheMemberFormerlyKnownAsAWOL:
Doesn't that just punch holes in the clouds?
Hehe, as a matter of fact, it can detect up to three or four layers of clouds!
thats why it costs up to €300.000 ....
I'm building a personal weather station for experimental aviation with temperature, rain rate, humidity, pressure and my next step is to detect cloud height and coverage...
any ideas are welcome
19W is certainly impressive, thanks. The efficiency is probably less than 25%, so you would need to put 80-100W in.
Do try the MLX90614. It is easy to detect cloud coverage, due to the IR radiation reflected from the Earth's surface, but if it were easy to measure distance, someone would have done it already.
i'll try this guy project!
https://create.arduino.cc/projecthub/KFMAKR/ceilometer-3339f0
rgusso:
i'll try this guy project!
That code is awful.
If you can make sense of that project posting and manage to get something running, let us know if it actually works. There are obvious problems.
This five part project, using the MLX90614 to detect cloud cover, is actually useful and practical.
jremington:
This five part project, using the MLX90614 to detect cloud cover, is actually useful and practical.
Yes, that one I posted is based on this one!
