Finally! Cheap TOF Laser Rangefinders are here :)

Niko,
Keep some notes, or some photos of what you did so those of us who wish to dabble can learn from your work, or just plain copy it to get some experience.

Is there anything about the duty cycle of the sensor? I know the folks who were working so hard on the Fluke/Porcupine combination that was so accurate were saying that the Fluke was sensitive to duty cycle and were only firing up the laser occasionally to try to maximize the expensive rangefinder. That just adds to the complexity of the programming and some degree the hardware.

I know these things are breath-takingly cheap but still to fry one to just pop another in seems wasteful.

Anything you’ve seen in the spec sheets on whether these can just be made, placed and then powered up to run?

Thanks for the update. Your reports are encouraging.
Dale

hi

amazing
still waiting for the post man ,
cannot wait to get this hooked up to Cloud IR sky temperature Project + addon uv - solar - rain plus snow sensor
this Project was only possible by Niko
thank you
http://www.weather-above.com/skyirtemp.html

It waits for a command and replies with an acknowledgement (if it was a setup command) or data (if it was a measurement command) so the user is in control of how hard it works.

Anything you've seen in the spec sheets on whether these can just be made, placed and then powered up to run?

There are so many possibilities I’m not sure how to answer that :dontknow: It doesn’t match any of the devices that WD currently supports for snow if that’s what you are thinking of. Probably the simplest would be an interface to make it look like the MB7354 ultrasonic sensor that WD does support. Anyone wanting to do their own thing can connect it to a PC with a cheap serial module and a simple program (Python?) can collect the data and upload to a website.

MichaelPT’s multi-instrument has a processor that is already collecting data from several sensors so hopefully we can just poll this sensor and add the data to packet it is sending to the PC.

One issue is that it is only sure to be good for about 1 meter/3 feet of snow, so I could see needing to build a unit with two sensors at different heights to extend the range.

Having this in test running on RasPi and measuring snow.
Gives OK values only when its dark outside. During daylight are the values (depending on temperature-fix) ca 195 cm.
This occurs only on snow, on soil, water etc is it OK.

weatherc:
Is the chip that doesn’t do well in the sunlight the Parallax chip, or the one that Niko is testing? I take it there are two different ones, from the links and not just a re-packaging of the same one.

I was worried about that, I’ll find some fake snow and test it later when the sun is up. The sensor chip datasheet claims "The VL53L0X

The Parallax one

It’s the same sensor component so it’s no surprise that I confirm weatherc’s results. Styrofoam sheet in bright shade is fine, but in full sun results in an FF error value in the serial data. Not unexpected from such a tiny micropower laser.

I guess a snow sensor that only measures overnight is probably still worthwhile considering the very low cost? At least it would show daily totals…

At least up here north at 60

Hi
this is probably going to be a silly suggestion, have you tried putting a sunglasses lens that are mainly clear then as the sun get brighter they go darker
some kind of reactive plastic lens

Just wondering if the laser sensor will go through such a thing but could help eliminate the bright light
mick

The reflected solar radiation from a white target is many, many times stronger than the reflected signal from the tiny micropower laser. (When you receive yours you will see just how tiny it is.) Anything we do to optically reduce the reflection will also reduce the laser reflection so it doesn’t change the situation, and it has to be out in the open otherwise the snow will be obstructed. Short of automating a sunshade when taking a measurement I don’t see any way out of this one :frowning:

Sounds like a job for a narrow bandpass filter - if you can find one at the correct frequency.

Agreed, the chip has one already, and one hopes the laser signal is modulated to separate it from the “DC” sunlight. However it’s a 940 nm laser and there’s a LOT of IR energy in sunlight at that wavelength :frowning:

I suspect the inbuilt filter isn’t very narrow or even a low pass, a good narrow band interference filter tends to be a bit pricey - going by my astro imaging experience. Though I guess the filter they use will be tiny.

It doesn’t need direct sunlight to show off.
During cloudy weather + resonable snowfall today did it show off whole day too.
Shade made with a piece of cardboard all the way from the sensor to the snow during sunshine do not help either.
From my and one other finnish tester tests have we figured out it shows correct from ca 30 min after sunset to ca 30 min before sunrise.
Once it gets lighter do it start to slowly rise the value until its close to 2 m. In the evening when it gets darker the oher way, it slowly drops the value until its correct.

On the good side, it measured correct todays new snow amount of ca 10 cm once it got dark. The values made with avergae of 15 readings are quite stable too (inside maybe 0.5 cm or so).

The datasheet admits that the outdoor performance is quite limited, max range is reduced to 50%. The outdoor test condition is:

"Outdoor overcast corresponds to a parasitic noise of 10kcps/SPAD for VL53L0X module. For reference, this corresponds to a 1.2W/m

multiply lux by 0.0079 to get wm/2 rough estimate

39.5 W/m2 - pretty shady.

Thanks.

Here it starts to work properly at 0w/m2.
Attached roadcam-pic some 5 km away, to give a glue about how dark/light it is at that point, is from 45 min before sunrise.


Hi

Just an update on my progress
please see images of the laser Control board

Circuit board design based on diagram from Niko Pic programme

I’m currently doing some tests , will update my website on how to make the circuit board and how to put the project together ,this was only possible with the help of Niko

thank you
mick


LASER1.gif