Trixology
WeatherCat => WeatherCat Feature Requests => Topic started by: Dicky_Knee on January 01, 2013, 07:42:19 AM
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Is there any plans in the future to support weather stations that output their data in NMEA format such as these:
http://www.airmartechnology.com/uploads/Brochures/WX%20Series%206%20page%20Brochure%20FINAL%20printer.pdf
cheers.
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It very much depends on demand - certainly very interesting kit, but yours is the first request we've had to support it.
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I think a lot of the mobile, portable, and marine weather stations output in the NMEA format, and as far as I know, there isn't any Mac application that supports it.
Steve
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I've had success with an iPhone app called NMEARemote (my station is setup with a RS422->Ethernet converter)
I've tried Weather Display (no NMEA support on the Mac version, the PC version seems flakey with NMEA) and wview (I couldnt figure it out) with no success.
I've tried running Windows based weather software (including the Airmar Software) in VirtualBox, with limited success.
I'm currently trying to write some excel spreadsheets to display the logged NMEA data (by decoding the $WIMDA string), but that is looking to be limited also.
so it became time to ask, hopefully i'm not alone in wanting to get these (otherwise very nice) weather stations working on a Mac.
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While there are no doubt some good instruments using the NMEA protocols, WC users should be aware that many of these instruments are designed for people wanting a indication of weather conditions for some purpose (eg sailing!) rather than a climate quality met measurement. Progress in electronics means that ultrasonic based measurement systems are becoming more affordable and new systems are beginning to emerge in the marine market (where NMEA is the standard). having an anemometer without moving parts on the hard-to-get-to top of a yacht mast is an attractive proposition. However having worked with ultrasonic anemometers/thermometers over several years I know that the accurate measurement of sound velocity over a short air path exposed to weather is a very challenging problem. Such systems can struggle to maintain accuracy if it is raining or even in heavy dew conditions. Research quality instruments tend to be larger (longer air path) and are much more expensive. I'd advise anyone thinking of using a relatively small, relatively low cost ultrasonic system to check that the accuracy specs are acceptable under all the weather conditions they want to measure. Some may be but for others, it's still hard to beat a cup anemometer!
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Thanks for the information, Peter. I've wondered how accurate the ultrasonic units were in real world conditions. It sounds like a good technology for applications where a more accurate anemometer isn't feasible.
Steve
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Don't get me wrong Steve, you can get very accurate ultrasonic instruments. A company in the UK, Gill Instruments, makes the research quality sensors I used to use and the present price for those is over ?9000. For that you get good measurements of mean wind and turbulence in 3 components from a relatively large sensor. A quick look at the Gill web site suggests that for 2 component mean winds their cheapest products are in the ?1000 - ?1500 range. I know of Airmar and Maretron weather stations being offered in the yacht equipment market - at around ?600 - ?700 in the UK and cheaper in the States. There may be others. Airmar quote 1 or 2 knot accuracy in the dry but only 5 knots rms in "wet conditions" and they say wet conditions include "moisture, rain, frost, dew, snow, ice and/or sea spray". Maretron quote 5% or 1 knot without any proviso with regard to rain. However they do say that "The WSO100 unit itself, especially the area between the transducers, must be kept clean and free of debris for maximum wind speed and direction accuracy". It would be interesting to see how the Maretron instruments perform with rain or ice in the sensing volume! I don't know if they also measure the temperature from the sound speed - if they do that could deteriorate too during rain. These ultrasonic instruments are certainly getting much less expensive and are certainly worth keeping an eye on but I just wanted to warn people that they may well come with a different set of problems than you are used to with cup (or propeller vane) instruments. Peter.