All that will get you is an average of crap altitude! 😀 Any agreement between GPS altitude and true elevation is merely a coincidence.
Regards, Garry Lockyer C: +1.250.689.0686 E: [email protected] > On Jan 10, 2021, at 18:33, Brent Dowell <[email protected]> wrote: > > Yeah, The first time I got the altitude I used a garmin gps and left it > running to average the altitude For a while. > > Guess I'm just going to learn to deal with it. >> On Sunday, January 10, 2021 at 6:24:56 PM UTC-8 [email protected] wrote: >> And this document explains why GPS altitude sucks (to be polite!): >> >> http://www.montereysar.org/SARMembersDocs/UsingaGarminGPSwithPaperLandMaps_Manual.pdf >> >> Regards, >> >> Garry Lockyer >> C: +1.250.689.0686 >> E: [email protected] >> >> >>>> On Jan 10, 2021, at 18:05, Brent Dowell <[email protected]> wrote: >>>> >>>  >> >>> >>> Thanks again! >>> >>>> On Sunday, January 10, 2021 at 6:02:00 PM UTC-8 [email protected] wrote: >>>> The note Derived variables from Davis has a pretty good discussion of this. >>>> >>>>> On Sun, Jan 10, 2021 at 5:38 PM Brent Dowell <[email protected]> wrote: >>>>> Correct Altitude is entered. >>>>> >>>>> I'm getting an average error of 3.5 millibars. >>>>> >>>>> My altitude is pretty close to the local airport, and I used a fairly >>>>> calm day to adjust my barometer to match that. Our altitude is also >>>>> relatively close, i.e. the airport is 4403ft and I'm at 4410. Althought >>>>> that 4410 could be off, I had used that for my altitude for years. >>>>> >>>>> Took another reading via gps today and have adjusted that to 4293, which >>>>> seems like it could be a significant differences. >>>>> >>>>> Thanks so much for your help in getting me to understand it. I've >>>>> managed to learn to ignore the wind errors, as I live on a hillside and >>>>> don't see anyway my wind data will ever match. if I need to do that for >>>>> barometer, I'll work on it. lol. >>>>> >>>>> Would just like to figure out what I'm doing wrong. >>>>> >>>>> >>>>> >>>>> >>>>> 1. That you have a Vantage console; >>>>> Vantage Vue Console >>>>> 2. That you are using regular LOOP packets, not the newer LOOP2 packets; >>>>> loop_request = 1 >>>>> 3. That you are using hardware record generation. >>>>> prefer_hardware >>>>> >>>>> From the wee_device command. >>>>> >>>>> BAROMETER CALIBRATION DATA: >>>>> Current barometer reading: 30.222 inHg >>>>> Altitude: 4293 feet >>>>> Dew point: 24 F >>>>> Virtual temperature: 32 F >>>>> Humidity correction factor: 1.1 >>>>> Correction ratio: 1.175 >>>>> Correction constant: +0.000 inHg >>>>> Gain: 0.000 >>>>> Offset: -16.000 >>>>> >>>>> >>>>>> On Sunday, January 10, 2021 at 5:01:53 PM UTC-8 [email protected] wrote: >>>>>> I'm assuming: >>>>>> >>>>>> 1. That you have a Vantage console; >>>>>> 2. That you are using regular LOOP packets, not the newer LOOP2 packets; >>>>>> 3. That you are using hardware record generation. >>>>>> >>>>>> If all this is true, then what's happening is that WeeWX is downloading >>>>>> altitude and temperature corrected barometric data (what pilots call >>>>>> QFF) from the console. However, CWOP wants pressure corrected only for >>>>>> altitude (not temperature; pilots call this QNH). So, WeeWX uses an >>>>>> algorithm to calculate that. This is then what is uploaded. >>>>>> >>>>>> First thing is to make sure you have the correct altitude entered in >>>>>> your console. You will also want to know whether the console is applying >>>>>> any barometric corrections. Both can be checked using the utility >>>>>> wee_device, with the --info command. >>>>>> >>>>>> wee_device --info >>>>>> >>>>>> This will tell you what altitude your console thinks it's at, as well as >>>>>> any barometric calibration data. >>>>>> >>>>>> -tk >>>>>> >>>>>> >>>>>> >>>>>>> On Sun, Jan 10, 2021 at 4:24 PM Brent Dowell <[email protected]> wrote: >>>>>>> I've been chasing my tail a bit trying to get my data that I upload to >>>>>>> CWOP to pass the madis checks, which, from what I've read is a bit >>>>>>> problematic. >>>>>>> >>>>>>> My question though is what should I have my console set as far as >>>>>>> altitude and barometer reduction. Right now I have it set for my >>>>>>> correct altitude and am using the altimeter setting. My readings are >>>>>>> consistently 'low' compared to the madis QC Check. >>>>>>> >>>>>>> It looks like to me that the values being uploaded are in fact low >>>>>>> (raw aprs data) and do not match whats on my console. So it appears >>>>>>> that weewx must be doing some altimeter calculation on my data and is >>>>>>> sending that on to cwop? I'm wondering if I'm missing a setting >>>>>>> somewhere in my weewx config to accout for that? >>>>>>> >>>>>>> Some of the research I've done on the issue talks about davis being a >>>>>>> bit of a pain because they out put the altimeter corrected data already >>>>>>> and that setting altitude to 0 and using the altimeter reduction fixes >>>>>>> it? >>>>>>> >>>>>>> Sorry about dredging up an old issue, but I couldn't find much recent >>>>>>> information on this. >>>>>>> >>>>>>> Thanks in advance for any help. >>>>>> >>>>>>> -- >>>>>>> You received this message because you are subscribed to the Google >>>>>>> Groups "weewx-user" group. >>>>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>>>> an email to [email protected]. >>>>>>> To view this discussion on the web visit >>>>>>> https://groups.google.com/d/msgid/weewx-user/d425ef32-4da0-49e1-b2d4-fd21dffdfbaen%40googlegroups.com. >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google Groups >>>>> "weewx-user" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send an >>>>> email to [email protected]. >>>> >>>>> To view this discussion on the web visit >>>>> https://groups.google.com/d/msgid/weewx-user/49100cc7-7e2f-478f-9065-f0f42a92db3bn%40googlegroups.com. >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "weewx-user" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to [email protected]. >> >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/weewx-user/9c6cfc66-af04-4813-83cc-8fc021e39074n%40googlegroups.com. > > -- > You received this message because you are subscribed to the Google Groups > "weewx-user" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/weewx-user/d4d43848-17c1-430e-9be1-665cdd974d58n%40googlegroups.com. -- You received this message because you are subscribed to the Google Groups "weewx-user" group. 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