[JT118]

I wonder if:

This could be read by Weatherduino,

https://www.darrera.com/en/detalle-produ...d=1&id=229

But expensive: http://www.meteo-shop.com/Prodotti/tabid...onico.aspx

it seems to be plug and play for a standard Davis, so assume it would work for Weatherduino. I think I have already put this on this forum some time ago.

More interestingly could this be made to put out a similar signal?

https://developer.sensirion.com/applicat...ing-sdp3x/

http://www.ebay.co.uk/itm/PRESSURE-SENSO...SwU8hY5oDE

Starting point: https://soldernerd.com/2014/11/14/arduin...g-started/

[werk_ag]

I wonder if:

This could be read by Weatherduino,

https://www.darrera.com/en/detalle-produ...d=1&id=229

But expensive: http://www.meteo-shop.com/Prodotti/tabid...onico.aspx

it seems to be plug and play for a standard Davis, so assume it would work for Weatherduino. I think I have already put this on this forum some time ago.

If they are made to work with the Davis, they will also works with the WeatherDuino Pro2.

With the WeatherDuino Pro2, the unit of the first link doesn't even need any additional power supply, as the WIND connector have the 12V to power it.

Electrical specifications
•Power supply voltage: 10 to 30 VDC
•Power consumption: 40 mA (max.)
•Output signal: Davis VP2 compatible

The second one is solar powered, so its just a matter of connecting it as a regular Davis Anemometer / Wind Vane

[JT118]

Yes for the manufactured ones,

I was really thinking about how one might make their own using the Sensirion
SDP3xx to produce a signal that Weatherduino could accept.

https://developer.sensirion.com/applicat...ing-sdp3x/

[AllyCat]

I was really thinking about how one might make their own using the Sensirion
SDP3xx to produce a signal that Weatherduino could accept. I assume the Darrera one uses similar, (if not the same) SDP3xx sensors.

Hi,

I'm rather confused that you seem to be mixing pressure sensors with an "Ultrasonic Time Of Flight" windspeed sensor.

The latter uses two pairs of Ultrasonic "Loudspeakers" and "Miicrophones" (at right angles) to measure how long it takes for sound to travel between one and the other.  The time delay reduces if the sound travels "with" the wind and increases if "against" the wind.  It's quite a difficult measurement as the speed of sound is around 300 metres/second.   The microcontroller then uses fairly simple trigonometry to convert the two windspeed vectors to a combined (linear) speed and direction.

It's quite an "advanced" technique, so the price is not overly surprising (for the claimed accuracy).  I'm more surprised that the Netatmo appears to do it for less than £100.  But that it uses 4 x non-rechargeable AA cells is probably a clue.  

Cheers,  Alan.

[JT118]

Thanks Allycat,

Yes I do realise one is speed of sound and other is pressure differential , ( Bernoulli, Pitot, etc.) and therefore not ultrasonic.

It seems both can be "home made" though the sensirion appears to rely on a rather complex piece of 3D printing to direct the airflow over the sensors. I assume the pair of sensors in the arrangement that sense the highest airflow will decide wind direction.

Also it seems as if the arduino ultrasonic system in the soldernerd link seems to have stalled as a project so perhaps it was difficult to produce a reliably precise measurement.

Just some thoughts for future add ons to Weatherduino (once the AQI project is complete!!)

[AllyCat]

Hi,

I must admit that I hadn't read that Sensiron Application Note, but it does say:

"Other devices ... like vane style ... or ultrasonic anemometers can be used to determine the speed and direction more precisely."

So it appears to be mainly intended for low cost and very small size, rather than accuracy.

An advantage of the cup anemometer and ultrasonic methods is that they have a linear response, so need only one-point calibration.  In fact the "time of flight" method is the only one I know of that can be "calibrated" by design directly from basic physical properties, so potentially doesn't need to be calibrated as such.  Having driven my car around with a GPS and anemometer on the roof and built an indoor "roundabout" for calibration, I can say from experience that even single point calibration is not easy. 

The Netatmo Anemometer is really rather interesting, but sadly appears to be a case of "style" over practicaliity (and perhaps also wild optimism).  The ultrasonic transducers appear to be facing out from a single plane, with the sound waves reflected backwards?  And to have designed it without  a solar panel and rechargeable batteries (which might also have helped keep the rain out) seems crazy.

Another interesting low-cost concept is the "RotoVane", a tagged cup anemometer invented by Derek Weston in the 90's.  It was manufactured and sold successfully under license for ten or more years, but he has now freely released all the (PIC) Source Code for anyone who wants to "play".

Cheers,  Alan.

[tobyportugal]

Hello,

Excuse my bad English, I use a translator.
I am amateur of precision, the sensors of winds " sonic " interests me.
Brand DARRERA is too expensive and construction makes " bad do-it-yourself” (see the necklace to fix the head!).
Brand LCJ definitely less expensive and in the beginning is developed for the boats.

http://www.lcjcapteurs.com/?lang=en
http://www.lcjcapteurs.com/wp-content/up...140617.pdf

If the speed of measurement of the WeatherDuino software is faster (2,5sec->Davis), it is a solution top.
Here comparative with the same step of measurement (2.5sec) on a VP2.
http://www.lcjcapteurs.com/impressions-o...2/?lang=en
http://www.rainwise.com/ultrasonicwind/
To imagine what that can give with a speed of measurement faster.

WeatherDuino + LCJ no weather stations compete!
I can try to obtain a price if several people are interested.

[JT118]

It needs to be able to use the Davis protocol. It appears that the LCJ is compatible.

http://www.lcjcapteurs.com/product/sonic...c/?lang=en

A price would be interesting, though possibly expensive. It seems approximately £600.00 .

https://www.svb24.com/en/lcj-capteurs-cv...ensor.html

New Davis ones run to £160+.

http://www.ebay.co.uk/itm/ANEMOMETER-WIN...SwECZUpBoL

[tobyportugal]

Version DVC is 100% compatible Davis.
This system is interesting for the short gusts of wind.

Good Sunday.

[AllyCat]

This system is interesting for the short gusts of wind.

Hi,

Yes it is a very interesting product, particularly for "extreme" weather conditions.  But the apparent price of 575 Euros + VAT is rather high.  It would be interesting to know how accurately it (or the Davis) can measure when there is  both wind and rain at the same time.

However, it is possible to achieve much shorter measurement intervals (or in very low windspeeds) by timing the period between two consecutive pulses from a cup anemometer (instead of counting the number of pulses in a fixed time).  But normally for meteorological purposes, a value over a "standard" time period (2 - 3 seconds for gust, 10 minutes for average) is required.

OT:  That a cup anemometer can respond quickly is demonstrated by the "Raymarine RotaVecta" principle which must change speed (and measure the time) within a small fraction of a single revolution of the cups.  See for example post#10 in another forum.

Cheers,  Alan.