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Arduino Based Weather Station


Gina

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Your ally pole get a suitable broom handle or hardwood dowel 2.8m length and push it through the ally tube so it won't bend in the wind and with a good fit allow the pipe to be clamped at the bottom......I have in the passed used plastic pipe with a wooden insert there very stable and cheap...

Edited by Tinker1947
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Your ally pole get a suitable broom handle or hardwood dowel 2.8m length and push it through the ally tube so it won't bend in the wind and with a good fit allow the pipe to be clamped at the bottom......I have in the passed used plastic pipe with a wooden insert there very stable and cheap...

The ali pole will be in two sections of 2" and 1.5" OD I think, not sure now - will have to measure them again (not doing that tonight though :D).  They are 5m lengths.

Here are some photos of the current wind measuring unit.  I have stripped it down for some mods and  improvements.  Now I have a lathe I shall be able to turn some new parts and make it more sturdy.  Also a mod to do on the wiring - direct power to the LEDs and not controlled by the 1-wire switch chip.

Firstly, the anemometer.  Currently the cups are on wooden arms and secured by hot melt glue.  I may have a rethink on this to prevent the cups flying of in a hurricane.

post-13131-0-50934700-1388867013_thumb.j

This is the underside of the stripped down wind vane unit showing the circuitry and blocks of LED/Phototransistor assemblies.  The LEDs are nearest the camera.  The chips are 1-wire components glued to the stripboard and wired to it with fine tinned copper wires.  The connections on these chips are 0.05" apart and the stripboard 0.1" matrix.

post-13131-0-82811300-1388867025_thumb.j  post-13131-0-41795300-1388869143_thumb.j

This is the encoder disc - crudely made but it works :D

post-13131-0-50692000-1388867036_thumb.j

Finally, the 1-wire circuit that reads the photo voltaic emf from the light sensor.

post-13131-0-82090000-1388867018_thumb.j

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First diagram is the current circuit for the wind module.  A mod is required to run the LEDs continuously from wired power.  The DS2413 connects the negative side of the LED circuits to Gnd to turn the LEDs on so this can simply be shorted out.  Then instead of using parasitic power for the circuit using a diode and an electrolytic capacitor, the power will be provided by another wire from the main unit.  See second diagram. 

post-13131-0-36816500-1388872311_thumb.j  post-13131-0-55578800-1388873524_thumb.j

In the photo below the connection from the 2K7 resistors to pin 6 on the DS2413 is the blue wire.

post-13131-0-86903100-1388874239_thumb.j

Edited by Gina
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I've always fancied trying to build an ultrasonic anemometer, but I think may be rather more tricky than it sounds at first.

James

Interesting :)  Does that use Doppler shift to measure the wind speed?

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Interesting :)  Does that use Doppler shift to measure the wind speed?

I believe so.  My understanding of the idea is that you measure the shift in both directions across the diagonals of a square (the system being installed in a horizontal plane).  By comparing the shifts it is then possible to calculate not only the wind speed, but also the direction.

James

Edited by JamesF
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You don't get a frequency shift (doppler) but you do get a phase shift according to wind speed, and correctable errors of coarse due to temperature and humidity.

So when using ultrasonics you need to measure the phase difference between the transmitted and received carrier wave rather than the frequency difference. If you use a Cortex M4F CPU rather than the much slower Atmel 8-bit CPU's you can remove a great deal of hardware and do all your processing in software by directly sampling the ultrasonic carriers (probably 40kHz) and doing some luvly DSP calculations (FFT, correlation etc), which makes it a much more reliable and accurate system.

The reason you don't get a frequency shift is because the transmitter and receiver are fixed relative to each to each other.

As well as having an X/Y ultrasonic arrangement (in a cross) to calculate the horizontal wind direction, you could if you wanted too add a 3rd Z axis (up/down). You'd then be able to calculate a true wind speed/direction in 3D space (vertical component as well as horizontal).

Edited by Cath
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Thank you James and Cath :)  My word, you certainly know your stuff Cath :)  That would certainly be a brilliant way of doing it if you have the knowledge but I guess I'd better stick with what I know for now :D

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I have done the circuit mods :)  Removed DS2413 and soldered the wires that went to pins 4 and 5 together to connect the 2K7 resistors to Gnd.  Then cut out the diode that supplied parasitic power.  The power will now be provided by a seperate wire directly to the Vcc common connection point (red wires).  The power Gnd is provided by the 1-wire twisted pair (the green and green/white wires at the left - green is DQ and green/white is Gnd).

post-13131-0-76985100-1388922237_thumb.j

Edited by Gina
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I did consider changing the optical encoder to use refllective sensors which would make the mechanics easier but OTOH it would need the electronics changing and also the optical sensor mounting - overall more trouble than improving the current optical encoder disc mounting to the wind vane.  I need to improve the vane bearing system anyway but all that is on hold until I get my lathe back together after the repairs and service.

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Thank you James and Cath :)  My word, you certainly know your stuff Cath :)  That would certainly be a brilliant way of doing it if you have the knowledge but I guess I'd better stick with what I know for now :D

I have to admit that it never for a moment occurred to me that it wouldn't be within your capabilities, Gina :)

James

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Hello gina 

i followed your DSLR Homebrew thread and found it very interesting.

i have just stumbled upon this thread and its sounds wicked what you are doing.

i also have a couple questions, 

i have a Multiwii flight controller. ( it is a arduino with a 10 DOF module ( 3 axis accel - 3 axis gyro, barometer, 3 axis magnetic compass )

this also sends pwm to four electronic speed controllers. these  are very small 45mm x45mm squared

GeKWeqHl.jpg

its an ATmega 328 ,  as you can see its just a small arduinio. 

without a reset button. this model does not have an I2C pin out, but using the ciruit on the top left 

you can gain I2C ( gps module ublox is what we tend to run here) at either 3.5v or 5v  using the curcuit 

just below it. 

now i was thinking of using this to control a couple DC motors via PWM as my  RA/DEC.

i then thought about using the baro as a hi/low pressure gauge, and the mag compass to be used with the

RA/DEC ( mixing it to give an alt dec reading ).

as you have and are tinkering with the same sort of idea, just not driving a scope mount with it.

what are your opinions on my idea, and have think about using breakout boards but dumped the idea for reasons ?

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The compas readings are unlikely to be anywhere near accurate enough for RA/Dec values.  You could use DC motors but then you would need some form of very accurate encoder to give the direction.  Better way and as used by all the commercial mounts I know of is to use stepper motors.  I would suggest you do that and drive them with EQASTRO or design your own Arduino sketch if you have the ability.

Edited by Gina
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Thank you James and Cath :)  My word, you certainly know your stuff Cath :)  That would certainly be a brilliant way of doing it if you have the knowledge but I guess I'd better stick with what I know for now :D

:)

It might be an interesting project for you then at a later date. Here's a couple who have already done the hard work ..

http://trekker.customer.netspace.net.au/wind.htm

http://www.technik.dhbw-ravensburg.de/~lau/ultrasonic-anemometer.html

It's quite interesting in that you can also measure air temperature at the same time using the system. You just extract the speed of sound from the data and their you have it - pretty much air temperature. Assuming that you send the sonic pulses in both directions (back and forth) to compensate for air temperature (without knowing it), which also happens to give you the required data to calculate the speed of sound/air temperature.

.

Edited by Cath
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:)

It might be an interesting project for you then at a later date. Here's a couple who have already done the hard work ..

http://trekker.customer.netspace.net.au/wind.htm

http://www.technik.dhbw-ravensburg.de/~lau/ultrasonic-anemometer.html

It's quite interesting in that you can also measure air temperature at the same time using the system. You just extract the speed of sound from the data and their you have it - pretty much air temperature. Assuming that you send the sonic pulses in both directions (back and forth) to compensate for air temperature (without knowing it), which also happens to give you the required data to calculate the speed of sound/air temperature.

.

Thank youvery much Cath - I'll study the info in those links and see if I could use it :)  One question will be the availablilty and cost of components (or is that two :D).

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  • 1 month later...

Now I have a 3D printer pretty much working (and it will be working properly once I've finished the various modifications, I'm sure :D) I shall be printing new parts for the weather station, particularly wind vane parts.  These will be designed in Google SketchUp which has the STL import/export plugin added for producing 3D printable output files.  I'll post the Sketch\up models and photos in due course.

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  • 2 months later...

Just something some may find interesting (or not as the case may be).

The VLT's in Chile (and no doubt most others) use ultrasonic wind speed/direction (in 3D) sensors. Here's a snapshot of one of Bradys videos showing a couple of the sensors.

post-20192-0-41192000-1398345059_thumb.j

Edited by Cath
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  • 1 month later...

With the 3D printer working well enough (just about) for printing plastic frames and other parts, I am redesigning the wind vane optical encoder using reflective IR optical sensors.  This will make the design simpler and easier to put together.  I have some cheap opto sensors on order and the exact details depend on these.  Meanwhile, I shall be designing the encoder in broad terms.

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  • 2 weeks later...

Here is a photo of the reflective encoder using a printed Gray code mask and an unwanted CD as the reflective surface.  These will be bolted directly to the wind vane hub.  The second photo shows one of the reflective opto sensors, simply consisting of an IR emitting LED and a phototransistor, side by side in a plastic holder.  These will be connected as before.  The specified distance of reflector from module is 12mm which will be easy to achieve.  I will be separating the tracks with partitions printed with the base plate.

post-13131-0-17757100-1402688619_thumb.jpost-13131-0-85797400-1402688625_thumb.j

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Model of the new base plate.  The opto sensor positions are just marked with holes for now.  I have added the separators though.

post-13131-0-26716800-1402699135_thumb.j

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I don't get a chance to read much if the forum these days but your threads are always fantastic. I love your designs and the way you think things through.

Keep up the good work gina your an inspiration.

How's your roof automated? I've forgotton what you did on that, I'm about to put a gate ooener on mine.

Sent from my GT-N5110 using Tapatalk

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