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By nikomas
#94969
Hello all. This is my first post :)

I am working on an university project which involves wind speed measurement.
For that purpose i have to use an ultrasonic anemometer, with small dimensions and low power consumption because i intend to use it in wireless sensor network array.

As an example i found theese two:
http://www.fttech.co.uk/ft702lm.html
and
http://emeraldinsight.com/Insight/ViewC ... 20304.html


But prices for these are much too high, much more than i can aford for this project.
Are there any other ultrasonic anemometers similar to these (maybe less accurate) and where can i find them?

Thanx in advance!
By MichaelN
#94973
Does it have to be an "off the shelf" solution? If so, then you'll be paying quite a bit. You might be able to pick one up "cheaply", such as this:
http://cgi.ebay.com/New-Vaisala-WINDCAP ... 3efd3f4780
http://cgi.ebay.com/New-Vaisala-WINDCAP ... 2c532bdc32
http://cgi.ebay.com/New-Naval-AGI-80896 ... 3efd0a4862

If you're looking to make your own, then you'll need to spend a lot of time and effort getting it right. To get decent accuracy requires significant signal processing. Here is one guy in Germany who did it:
http://www.technik.ba-ravensburg.de/~la ... meter.html

PS: can you give us more info on your project? Sounds interesting!
By nikomas
#95115
Thank you for quick answering.

I am working on a project that is in cooperation with masliNet ( http://www.maslinet.com/eng/main.html ), a project that aims to apply wireless network sensors in agriculture (specifically olive growing). Its mainly a student project (Croatia university)...

My project is to make a compact meteorological station, which implements temperature, moisture, humidity and wind sensoring and reporting. At first, the plan was to use ultrasonic sensor for wind speed measurement, but i cant find one that fits our budget.
There is not really enough time or resources to make such a sensor from scratch, and it exceeds the range of this project. So if i cant find a cheap ultrasonic sensor, i will have to come up with alternative solution, bearing in mind low power consuption requirement.
So if anyone knows any cheap ultrasonic sensor, please tell me.. If not, it would be great if we could brainstorm for some alternative solutions...


Thank you!
By MichaelN
#95154
Sounds like a great project. There's a number of people doing similar things here in Australia to control irrigation systems, since we need to use water very carefully.

As for a wind / direction sensor, I wouldn't worry too much that you can't use ultrasonic because of budget. I think everyone else doing something similar to you is using the normal "cup" anemometer and windvane.

Do you just want the sensor to connect to your own wireless hardware, or would you be interested in something that has wireless capability built-in? There are plenty of wireless weather stations / anemometers out there (Kestrel makes some of the more popular units).

If you just want the anemometer / windvane, there are plenty of companies that offer this, eg:
http://www.aagelectronica.com/
By nikomas
#95518
Sorry for delayed response...

I want to connect the sensor to my own wireless hardware, so it would be better if it didnt have wireless capability built-in....
By nikomas
#96312
After a detailed analysis, i have decided to make my own sensor, and not to use ultrasonic principle.

Now i have to choose another method that would meet my already mentioned requirements.
I would like to avoid ones with moving parts, and prefer the ones based on hot-wire methods.
Do you have any suggestions about such methods, examples of implementations, or useful links i should take a look at?


Thanks!
By MichaelN
#96315
If you don’t care about wind direction, the “hot wire” method is quite “easy”. I believe some people have used the tungsten filaments from a low-voltage globe. If you carefully break an automotive globe (for example), you should be able to fit the globe (minus glass) into a standard globe holder. However, the orientation of the filament will mean that wind from different directions will affect it differently. You want a globe with a “vertical” filament I think.

Years ago, I made an airflow sensor that was quite accurate, and wasn’t as delicate as using a globe filament. It used 2 identical 3-terminal SMD temperature sensor ICs (I can’t remember the type, but they were SOT-23 package). One of the sensors was mounted on the PCB, and the other was mounted on 3 short lengths of wire (i.e., standing off the PCB). The second temp sensor had an SMD resistor soldered across its power terminals to provide heating. I used an op-amp to measure the difference in temperature between the heated and unheated sensors, which gives a measure of airflow. You could also directly measure the output from each sensor with the ADC inputs on a microcontroller.

Note that these types of sensors measure MASS airflow, not absolute airflow. The amount of air flowing over the sensor depends on the air pressure and temperature, as well as its velocity. If you’re measuring the temperature and air pressure, you can correct for this.

If you want to measure wind direction as well as speed, the “hot wire” method becomes quite complicated (i.e., it detects how much a central “hot wire” heats up several sensors that are located around it).
By VENTS
#115553
LCJ CAPTEURS is the leader in creation of compact solid state wind sensor for sailing ship, yachting, fishing, coastguard, buoys, data aquisition ....since 10 years and now for land apllications.

We present the CV7 to you:
CV7 Ultrasonic wind sensor & CV7SF Wireless Ultrasonic wind sensor.
We will be happy to supply any additional information you may require about materials.

Yours faithfully,

Christophe MICHEL

LCJ Capteurs
ZA Le Chêne Ferré
44120 VERTOU
France
http://www.lcjcapteurs.com
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By MichaelN
#115555
VENTS wrote:We present the CV7 to you:
CV7 Ultrasonic wind sensor & CV7SF Wireless Ultrasonic wind sensor.

Christophe MICHEL
http://www.lcjcapteurs.com
Hi Christophe - I'm interested in this. Can you please provide more information on the CV7SF Wireless unit? I couldn't see anything on your website about it. Also, can you give an idea of prices for these units? Thanks!

PS: it would be helpful if you had more of your website available in English, although Google Translate did a reasonable job...
By VENTS
#115559
Hi Michael,

You can see:
http://www.lcjcapteurs.com/wp-content/u ... df_Ang.pdf


European public unit prices:
CV7SF: 575,25 Euros ex VAT FOB
CV7-V: 575,25 Euros ex VAT FOB
CV7: 515,00 Euros ex VAT FOB

All sensor work with NMEA0183 : MWV sentence at 2Hz
For racing or hight-resolution applications, we have a 4Hz output option.

Christophe
Last edited by VENTS on Sat Feb 02, 2013 2:55 am, edited 1 time in total.
By MichaelN
#115582
Thanks Christophe. While the wireless unit isn't suitable for my application (I need much faster sample rates - at least 4Hz, and longer range), some of the other units may be suitable.

I'm still looking at whether my application is cost-feasible, but the prices you gave seem to be favorable compared to other ultrasonic units.
By MichaelN
#115614
VENTS wrote:Hi Michael, Is this a personal project or an industrial project?
It's a product I'm developing for a niche market, in response to requests from people in the industry. Potential sales are in the order of several hundred to about a thousand per year. Sorry, I can't provide more details about the nature of the at this point.