Topic: Vastly different wind speeds on two consoles???

[smorris]

I have the Davis VP2 with wireless anemometer transmitter. I have a VP2 console in my kitchen, and another on my desk next to my computer. Both are plugged in to AC power. Wireless anemometer transmitter is set to channel 1, ISS on channel 2, and both consoles set properly.

We've got some strong wind blowing through at the moment, and I'm getting vastly different wind speeds on the consoles. THe one in the kitchen was reading upwards of 25 mph while the one on my desk was reading 7-12 mph. This wasn't just instantaneous, but for an extended time.

Why would I be seeing such a big difference? I normally wouldn't have noticed, but I've been saying that I need to get my anemometer higher, as it was only displaying 12 mph. My wife was in the kitchen and said it was 28 mph in there. Weird!

Steve

[dalecoy]

According to http://www.avon-weather.com/graphs.html  your average wind speed is running around 12, and your gusts are showing in the upper 20s.

I would start by checking to see that both consoles are set exactly the same.  That would include things like which graph is selected for display on the console, and that the other things (seemingly unrelated things like wind chill) are the same. 

Oh, and the console firmware version is the same?

[4wd]

There is a setting for wind cup size would make a big difference.

[johnd]

I would start by checking to see that both consoles are set exactly the same.  That would include things like which graph is selected for display on the console, and that the other things (seemingly unrelated things like wind chill) are the same. 

And that the wind speed units are definitely, categorically, both set to MPH.

Agree on the console firmware too - if one of the consoles has an older firmware version then it will potentially be using a different lookup table for the wind speed corrections. (TBH I wouldn't expect this to make much difference at wind speeds as low as 20-30mph but it might be one factor out of several that accounts for any difference.

Nobody else nearby who might also have a VP2 Tx that one of the consoles could be picking up in preference to your own ISS?

[dalecoy]

There is a setting for wind cup size would make a big difference.

Why would that make a big difference?  Especially, why would it make a big difference at 12+ mph wind speed?

[smorris]

OK, here's what I know so far.

First, I made a big mistake by not checking reception before I got into the setup screen, so I don't know if there were reception problems.

I went through both setup steps, and everything was set exactly the same.
Both consoles are firmware rev 1.90 US English.
Both are set with the large anemometer cup.
Both have Wind on channel 1, ISS on channel 2, and Leaf/Soil on channel 4
Both units are plugged in, so battery should not be an influence.

I have had occasional problems with the kitchen unit not sensing changes in the solar sensor, which leaves me to believe that it gets intermittent signals in the kitchen. But the anemometer transmitter is about ten feet from the kitchen console, right outside the window, and has always been responsive.

So after going through setup and clicking "Done", my wind speeds are now identical! Crap! I fixed it and I don't know what I did...


With both units sitting side by side on my desk, I get 99% reception. Both show two bad data packets since finishing setup (about ten minutes.)

Moving to the Reception diagnostic screen 2, both show signal strength of 38-44. Moving the second unit back to the kitchen results in receptions in the 35-50 range.

Question: How do I know what transmitter I am checking reception on? Both units say "Station No 2" at the bottom during reception checking.


As far as I know, there are no weather stations of any kind within at least a couple miles of me.

Thanks for everyone's input!
Steve

[dalecoy]

I went through both setup steps, and everything was set exactly the same.
...
So after going through setup and clicking "Done", my wind speeds are now identical! Crap! I fixed it and I don't know what I did...

Setup isn't the only way to change things - for instance, graphs (and graph mode).  Something you did in setup may have caused some other side-effect, even if you didn't actually "change anything in setup". 

And what you did was "fix it".  Yeah, I know - what if it happens again?  Doubtful, but possible.

Question: How do I know what transmitter I am checking reception on? Both units say "Station No 2" at the bottom during reception checking.

As far as I know, there are no weather stations of any kind within at least a couple miles of me.

First, don't try to check if nothing is wrong.

The most straightforward way is, if something seems wrong, go to the appropriate transmitter and turn it off.  If one of the consoles is still receiving, you've identified the problem.

[C5250]

Question: How do I know what transmitter I am checking reception on? Both units say "Station No 2" at the bottom during reception checking.

That's the station it's showing statistics for. The right arrow cycles through the screens for each configured transmitter.

[smorris]

Thanks guys! I'll keep an eye on it, but it is working fine for now.

Steve

[DeKay]

As far as I know, there are no weather stations of any kind within at least a couple miles of me.

My guess is that you're picking up another station in the neighborhood that you don't know about.  The packets are CRC checked and the console rejects those with errors.  So it won't display wrong data, but it can display someone else's data.

[archae86]

So it won't display wrong data, but it can display someone else's data.

Yes, and it can look rather confusing, as when it happened to me during initial setup, I got a mixture of a neighbor's data and my own.  I finally guessed what was going on when I continued to get wind data despite having unplugged the anemometer cable from my ISS!  His station was at least six hundred feet away. 

If you have any doubts, it might be wise to change channels on your transmitters.  If you still have reception on detected on channel 1 that is your neighbor speaking.

[smorris]

I don't think it is neighbors, as every other reading was identical. And what are the chances of a neighbor not only having a VP2, but one with solar but not UV AND having the anemometer on a separate channel, and different than the recommended channel to boot.

I'm in a somewhat rural area, and know most of the neighbors within several hundred yards. Plus we walk all over the place and I've looked for weather stations. I know of one plastic one about 1/2 mile alway, but the anemometer is missing a cup and it never spins. I think it was just something goofy with mine. Both consoles are still reading identical today.

THanks,
Steve

[d_l]

Steve, I strongly suspect that you were originally receiving some neighbor's data as well.  When you ran through the set up again, your console finally got a lock on your ISS.  Reception of your ISS data might not last if there ever is an interruption in the console's power supply or if you service your ISS or there are some weather conditions that interrupts the signal strength to your ISS. In otherwords, your console's reception could revert back to the neighbor's at times.

[dalecoy]

OK, so I'll bet that it wasn't a neighbor's station, and will never be a problem in the future.

[KF5APO]

My guess would be and off brand weather station possibly operating on the same frequency as the Davis VP 2
though the odds of this may be very remote it's still somewhat possible. another guess would be Band Conditions
of the Radio Frequency Spectrum. if band conditions are just right even a low power transmitter can be heard beyond it's normal range.
Good luck Steve!.
73 de  ( Best Regaurds from)
KF5APO
Andy.

[dalecoy]

My guess would be and off brand weather station possibly operating on the same frequency as the Davis VP 2

KF5APO
Andy.

Using FHSS with the same pseudo-random sequence as Davis? 

 another guess would be Band Conditions
of the Radio Frequency Spectrum. if band conditions are just right even a low power transmitter can be heard beyond it's normal range.

KF5APO
Andy.

Persisting for hours at a time?  And on the 900 MHz band?

Occam's razor?

[KF5APO]

I know it sounds a litt out of the Ordinary but, with many Cheap weather stations it's possible.
and, it's also possible that his weather station console could have been picking up another possible
Davis VP 2 Wind station further away than just within walking distance.
with Band conditions Rising or falling  Tx/Rx range can improve or quickly Change.
anything is possible. though I'd agree the "Spread Spectrum" Frequency hopping technology the Davis VP 2's use should
Rule out any possible interference. Unless, it was another Davis VP2 Station.
Remember I'm just taking a Guess here based on my experience with radio's Changes in the bands.
Andy

[dalecoy]

Perhaps I should have signed my posting differently.

W5VBQ

[KF5APO]

Perhaps there were a few mistakes on my end too.
though it is a possibility that Other weather stations using the "Spread Spectrum" Frequency hopping
hardware could be very close to the Frequency of the Davis VP2 after all I studied about the possibility of
Overstepping the frequency at or near the edge of the band.
Not that I'm saying any of Our, theories are wrong.
Intermod  interference is the terminology I was looking for to sum it all up in my previous details.
This is still an interesting puzzle to figure out if it was a setting that was causing the malfuction
or possible interference from Other sources.

73 de ( Best Regaurds from )
KF5APO
Andy
 

[smorris]

Thanks for the speculation guys. Everything is still working properly, so I must have had some glitch.

[dalecoy]

OK, so I'll bet that it wasn't a neighbor's station, and will never be a problem in the future.

Glad to hear it's still OK.  Please let me know if you find out that my bet loses.