Weather station suggestion - WMR200

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1

I want to buy a beyond-average-equipped weather station.
I’d prefer wireless, to make it easier to find a good spot for the sensors. (Must be 433Mhz)
(How long does the batteries actually live, if the sensors keep transmittion more or less continously?)

I’m looking at Oregon Scientific WMR200 and Davis Advantage 2 pro.
I want background light on the screen. Thouch screen might be cool.
I would like some historic data to be displayed. E.g last 12 or 24 hrs, maybe… (and pc-communication)
Temperature, windspeed, wind direction, humidity, temperature corrected for wind speed, UV-reading and so on… More is better… :wink:
Any model have a readout for when the daylight turns to night? It follows a pattern of course, but it may vary from day to day because of clouds and time of the year. I can look it up in a calendar, but better to have it displayed.

Found some posting about problems with the sensors for Davis, seems to last very short…
I’m thinking of buying from the US, because the price is a lot lower there… But quality is a factor then…

Suggestions? I’m a newbie here…

2

It would help to know where in the world you are. Also be aware that US wireless will not be legal in the EU, Australia or NZ and probably other places as well. Why 433mhz? Davis is not that frequency.

Stuart

3

I’m in scandinavia - Europe.
433Mhz, because I belive this is the frequency that is allowed in europe. Seen it on such and other wireless devices…
I’ve been googling around a bit, and I thought I saw Davis had eu-models… (maybe not)
Well, then the Oregon is the one maybe?!

4

I use a Davis VP myself
all stations do run into problems with some of the sensors at some stage in their life
Davis have a very good support system

5

868MHz is the frequency used by Davis VP2 stations for the EU (and indeed for most locations outside N America). This is one of the official scientific telemetry bands.

6

I live in Norway and went from an Oregon WMR-200 to a Davis VP2 Plus Wireless (model #6163) with a 24-hour fan aspirated shield.

They are not comparable, the Davis is of very high quality but the Oregon was mediocre.
Point is, here in Europe/Scandinavia they are in two completely different price ranges.
So it’s not really just to buy the Davis, you will have to put quite a bit more money in it.

It’s better to invest more now and be happy, than to buy something cheap and not be happy (like I did to begin with).

433 MHz is only one of many license-free bands to transmit on, Davis use 868.0 to 868.6 MHz for the overseas models (Europe etc).
So don’t worry about that. If it wasn’t allowed, they couldn’t sell it here.

The range on the wireless Davis is much better than Oregon as well.

Good luck,
-Martin

7

If you try to buy direct from the US it will (so far as I understand) be a US model that is shipped.
broadstairs mentioned this earlier in the topic, but is is not quite clear from your reply that you picked up this aspect.

8

I think there are three good options in no particular order.

  • Davis Vantage Pro 2
  • Oregon Scientific WMR-928/968
  • Oregon Scientific WMRS-200

Davis: very good on all aspects, good support, compared to Oregon really expensive but compared to others not expensive at all. Certainly not when you consider the build quality AND expandability. It is unbeatable from that aspect/ You can add UV meter, solar radiation meters etc. Build quality seems to be the best in the price range up to 1000 euro. It measures every 2,5 seconds!!!

Oregon WMR-968/928 (US/EU models): good quality, mediocre support, very good accuracy, very good range, very low price! Measures every 37 seconds. Wind every 14 seconds, gusts in between are stored!

Oregon WMRS-200: same as WMR-968, but the range is may be somewhat less, accuracy good, if it performs like the WMR-200 it has a unbeatable low price in my opinion.

My experience is with several Davis stations and Oregon Scientific. Problem: I do not own the Oregon long enough to say anything about the quality, but it is fair to say that most Oregon owners on the forum seem satisfied with their stations.

What can I say about Oregon, also compared to my Davis stations?

For one: Oregon is really modest about the specifications, that is 100% sure when it comes to the WMR928/968 series.

Range: 100 m in line of sight. My experience: aboutleast 200 m without any line of sight. I have it on rapid fire. My meteohub immediately sends a mail whenever there is a sensor receiving failure and in the last two weeks (since I got it to the internet) I have had 0 mails.
I did a long test on this, as I wanted to set things up according to WMO standards when it comes to the site. I took the anemometer and hold it until I was more than 300 m away. The receiving display was in the barn and the signal had to pass at least 3 thick walls. Then I let it go for 30 seconds, hold it firm after wards. The only gust could have been from that position. I have repeated that many times, but the signal was picked up time and time again.

Accuracy: they say +/- 1 K and +/- 10 % for the thermohygrometer. I don not know about the rainmeter, barometer + or - 10 hpa. The last one is preposterous. They are very accurate.

I have tested the TH and B meter on site at KNMI Vlissingen, standing next to the radiationshields. Of course the TH meter was in a sensorshield. I did this many times. The difference was never more than 0,2 to 0,3 K.
I als have a calibrated thermometer next to my WMR-968 on my site: the same small difference. It is pretty constant, because the datalogger is very fast to respond. The WMR-968 thermohygrosensor is still a fast responder nevertheless ! I have also two spare thermometers for a WMR(S)-100/200. While these are about as accurate, they are slower to respond. This is not always bad btw…

Comparison with Davis Weathermonitor 2: Oregon is somewhat more accurate and clearly faster to respond. Do not know about the Vantage Pro 2, but on paper it has the same accuracy as the WM2. May be it is faster though…

Rainmeter: really accurate, but it lacks resolution. Did no on site test, but have a lot of KNMI stations very nearby (few km). Well: my Davis lost (many) millimeters in downpours. The mechanism can’t keep up due to the high resolution. May be the Vantage Pro 2 rainmeters have become better. Oregon does not loose millimeters in downpours! But all Oregons loose mm when amounts < 1 mm fall down. It just lacks resolution. I feel that this is the only true downside.

The barometer: more of the same. Really accurate after adding a calibration factor (sea level adjustment on the display). I am always within 1 hPA and most of the time 0,5 hPa compared to KNMi Vlissingen. Also on site. This is in the range between 995- 1040 hPA. Resolution is 1 hPa. Davis has a better resolution ( I believe 0,3 hPa), but not more accurate.

Wind: okay. But did no field test. A very strong signal as I have told, better than WMR(S)-200 but the last one seems to be more responsive.

Finally WMRS-200. If it is exactly the same as the WMR-200, but without the datalogger I honeslty think this one is the best bang per buck nowadays. It lacks a display, but when attached to a PC that won’t be a problem I guess (well not for me).

You have to buy or build a good radiation shield. You will find many good examples on this site about how to build a good one yourself (Breitling has an excellent topic here on how to do so).

Now I use an RFXCOM receiver that receives almost all Oregon Scientific sensors. It is about as good as the OS display (receiver) when it comes to receiving signals. I also have a UV meter that isused for WMR-100/200 series. And if this is an indication for the range, I can tell you that this one two has little problems in reaching 170 m without a line of sight…

One important note here: my station is in the country, the receiver is in a barn and I have most likely very little problems with signals that disturb my sensors. In the house next to the barn there is wireless internet with some laptops and a wireless phone, but the next door neighbours are 500 meters away.

Till know I have to say that I am more than satisfied with all aspects of the Oregon Scientific 928/968. Even somewhat happier than with my Davis, because the Davis had some freak signals every now and then. I believe this is more a problem because they were wired. The rainfall was sometimes a problem. Hope the quality is good enough though.

If you want to read a test (p

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I bought a La Crosse 2350 and later added a Hobby Boards solar sensor. I thought to myself I just wanted some basic weather - then I got addicted.

For the price the station is fair, but it is kind of like having an exotic animal with a strange desease, it needs constant nursing.

I think that is good advice.

You might also think about what it is you actually want to measure. Do you want to be “scientific” or do you just want to know the weather in your garden.

Temperatures will be different in different parts of the garden, “scientific” wind measurment (according to the Swedish standard) is at 10 meters above ground level (I did decided I’m up there so seldom, I don’t need to know).

If you are going the scientific route - it involves a lot.

If you’re going for the weather you can experience yourself, that is simpler.

My experience is that setting up a weather station will inevatibly lead to surprices - so a tip is to not make too permanent installations to start with.

Last but not least; every living organism love cables, cats, dogs, mice, children and neighbours just can’t stay away from them. Stay away from cables. No one can nibble on wireless.

Davis seems to be cheaper in Norway than Sweden, see: http://www.wewind.no/shop/ and http://www.prisjakt.nu/produkt.php?p=214738

10

Thanks for a lot of informative replies!!
I’ve been considering and comparing prices and devices.

I think I’ll go for the Origon VMR200, and possibly at www.pixmania.com .
The Davis Vantage 2, which I’ll probably will have to buy in europe to get one that transmits on a legal frequency, will be at a higher price than I want to spend… It may be the Rolls Royce in performance and quality, but for me this is “for fun”, so I’ll start with a mid-range device.

Of course I’ll be dissapointed if the Oregon shows values completely out of range, and is very inaccurate, but from what I read, this unit performs pretty well, and have more or less all the functions I ask for.

There is also a model from La Crosse: WS2-550, may be in the same league…?!

Since i live in Norway, and will have snow during the winter. Will the rain-sensor also measure snow as rain, or does the rain-sensor need heat to make the snow into rain first?

Any comments to my choice is very welcome :slight_smile:

11

It ought to be okay - if you get results that bad you’d have a faulty unit!

In June I wrote a few comments about the WMR200 (and WMR928) over in
http://discourse.weather-watch.com/p/252426
3 months down the road I don’t disagree with what I wrote earlier. :slight_smile:

The only refinement I’d add is that, since then I’ve moved the WMR928 anemometer to a 5m pole. The WMR928 now records windspeeds and gust 10-20% higher than the WMR200 (which is still at just over 2m). When they were similarly positioned the WMR200 caught higher readings than the WMR928.

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I think Davis is very good when it comes to built quality. The accuracy…I think it is somewhat exaggerated. I understand that people are happy with their stations and rightfully so. You pay a lot and you get a good signal, a station that has many capabilities, it is reliable and also expandable with solar and UV sensors. And the only one out of the box with a good radiationshield! This combo is better than anything on the market under 1000 euro’s. But building a good radiation shield (or buying one for 80 euro or so) is pretty easy to do or cheap and this alone changes the situation in favour of other stations, in my opinion, because they are about as precise or even better in some aspects while costing (much) less.

Not many have actually tested (or continuously) test their station with calibrated min/max thermomer or even better: compared directly in the field with the stations of the national weatherservice. I did and do both. I did so with my Davis and I do so with my Oregon WMR 968. I have already told you that the Oregon has a more accurate temperature measurement than all my Davis stations. At least my unit does. Considering the Davis as a Goldstandard is not justified from that perspective.

Now Skye told you about intercomparison and calibration of the anemometer of the Oregon with a Davis…Just today I found these results of a Davis Vantage Pro 2 tested the last couple of days with the Hungarian Bureau of Meteorology with a calibrated Vaisala unit. It is an Excel file.

http://www.wetterstationsforum.de/phpBB/download.php?id=7877&sid=a96d5439b5df4c051e0c459cdf9b149a

This indicates to me that it is a good station indeed. Here we see that its anemometer actually measures too much wind…10-20% too much. Now this may vary between units, but it is a clue not to do calibrate against a Davis. Oth: most people measure in situations not ideal for measuring true wind speed, so this could compensate for those not ideal setups.

This tests also shows larger deviations of up to 1,1 K (to warm) at -20 C. It is rare in Holland to measure this temperature (we get to -28 or -30 at most every other century haha), but in many places in Norway you will reach this more often. In my case, I had deviations of 0,6 K (after calibration of the Davis unit on the unit itself, otherwise it would have been bigger but this is also true for Oregon). This is measured in the range of -15 to + 36 C in my situation here in Holland. We have a very temperate climate over here, as you can see.

Now compare this with tests in the same situations, so with official calibrated instruments in a lab by German testers, results were displayed in a magazine for electronics.

Oregon WMR 968: range -2 to +2 C, deviation: 0 to 0,3 K deviation. From -10 to + 40: maximal deviation -0,5 to + 0,4 K.
Relative humidity: -1 to 0,8 % (!), range unknown
Windspeed: -2 to 0 m/s (so never too fast, but almost always too slow)
Airpressure: -0,7 to 1,28 hPa (range unknown).

Unfortunately they did not compare with Davis, but did so with other stations which showed much larger devations on some aspects.

One thing: build your own radiationshield or buy one with almost every station, apart from Davis. Otherwise pretty accurate temperaturereadings are really meaningless, as the Oregon Radation shield has a pretty bad construction!

Melting snow…over here, the maximum amounts of snow cover and falling on one day in the last couple of years have been 30-55 cm and on more than one occasion. Apart from the southeast, these amounts where noted all over Holland. So many weatheramateurs have measured it with heated rainmeters. I have heard of no complaints of people measuring this snow with heated rainmeters. A Davis has a larger funnel and it is easier to fit a heater in it. But you can put these things in an Oregon aswell. As the suface is smaller it should be easier to heat it.

I would not buy a La Crosse 550 (ELV in GErmany). The signal is really bad, many complaints about signal loss, about faulty units, about failing sensors. It is used quite often in Germany. And they do not measure nearly as often as Oregon, let alone Davis. Windspeed and gusts are measured really well with Oregon and Davis. Oregon has a memory for every gust and apart from that every 14 seconds there is a measurement. Davis measures every 2,5 seconds! ELV every 3 minuts for all values. That is really mediocre.

Well, hope this helps you.

Hilsen,

Jorge

13

i wonder if maybe they had the wrong cup size set on the console when comparing to the vaisala?
my davis windpseed compares good with my maximum anenometer (voltage/frequency system)

14

Ideally you need a heated rain gauge. I am living in the mountains so I’ve installed a heater inside the rain gauge so that it can melt the snow in order to measure the water equivalent.

Unless you install a heater and the weather is cold (over a long period) the ice can freeze the trigger mechanism and the snow will of course cover the gauge completely.

Best Regards,
Martin

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I truely don’t know, but why would they? From the comments of this Hungarian guy in German, it seems they just used the Davis as it is.

" Verfasst am: 15.10.08 - 09:16 Titel:

16

Do you have an OS source for that?
I’d love it to be the case, but I’m far from certain that it is.
I’m sure I’ve seen cases of wind data transmission where the gust reading is less than the average.
I think I’ve seen that with both the WMR928 and WMR200 (a close study of the Meteohub ‘raw’ data files might produce some samples, but I don’t have time for that at present).

The only way I can explain that situation is if the gust is based on a reduced sample (e.g. the number of turns in the last second before tramsmission) and the average is based on a longer sample (e.g. the number of turns in the last second before tramsmission).
Edit: Opps. I did a copy & paste and forgot to edit - so the ‘average’ case ought to read ‘(e.g. the number of turns since the last tramsmission)’ :oops:

I’d love to be proved wrong. :smiley:

17

its widely posted on forums over the years that the OS stations are poor performers for current (gust) and average windspeed (i.e the average takes a while to come up, etc)

18

Agreed.
Though on price/performance/convenience(i.e. wireless) the OS are a great deal, and I’m happy with the purchase(s).

For better wind data within the budgets I have in mind I’ll probably need to solve the problem of getting wires out to the sensors and go for either an Inspeed Vortex or an AAG/1-Wire…

19

Well, in a windtunnel it is tested the way it is. Maximum deviation was -2,2 m/s unfortanetely the testers did not display the range. -2,2 m/s is a lot when the wind i 4 m/s but it is less so when it is measured when the actual speed is 35 m/s.

I use an Oregon WMR 968 on a 4 m pole in the open and I’d say that it measures pretty accurate, but of course I cannot say it actualy measured 2,2 m/s less than it should or not. I think that many problems with OS windspeedmeters are the positon. Who measures in the open on 10 m height? Who has compared with a calibrated one on the same pole. That is a true comparison, the rest is anecdotal. I am not too fond of that. And if Davis measures more people may be are ready accept that that isoke, while the test shows it isn’t. Would be nice to compare, to see what happens…

The gusts btw recorded in between the 14 seconds, the testers found it out. if you know how to read german, you can read it here:

http://www.wetterstationsforum.de/wmr200.php

it says: Much to our hapiness we could found out that the station also keeps the windgusts in between the 14 second period.

best regards,

Jorge

20

I think the trouble with these one-off trials/tests (of which there are several scattered around the web or reported privately and which in general show the VP/VP2 systems as performing well in respect of accuracy vs specification) is that they are almost always - for understandable reasons - trials of just one individual example of a station. As such, they are a sample of one and hence virtually impossible to use as a basis for drawing statistically valid conclusions about the model range in general. There’s always the possibility that the individual example chosen was a particularly good or bad example of its type. Only a trial using multiple randomly-chosen examples of the same station and tested under carefully-designed and thoroughly-documented conditions, which isn’t usually the case, is likely to yield a definitive answer. Such a trial is very unlikely ever to happen.

For what it’s worth, I’ve seen reports from experienced UK observers at several different sites over the years comparing WMII/VP/VP2 temperature data, for example, to accurately-measured max/min data from standard thermometers and there is a surprisingly good correlation with small absolute deviations in mean values. But at the end of the day this is just another anecdotal statement. Maybe one day someone will try to collate and publish all of this scattered data, including the various reports that have never been uploaded to the web.

But one other way to judge the likely accuracy of a station is the care with which the specification documents are drawn up. If you look for example at the Davis specs - see eg the various PDF specification sheets available at:

http://www.davisnet.com/support/weather/support_docs.asp?dtype=2

you’ll find a considerable amount of care and detail in setting out the comprehensive data, including for instance a graph that shows the dependence of the temperature accuracy on the current temperature value. I’ve yet to see anything remotely similar in terms of detail from Oregon, for example. All too often all that’s quoted is resolution data, which is essentially meaningless of course as a surrogate for accuracy.