This is Matthew's baby. Matthew? -tk
On Fri, Feb 14, 2020 at 10:11 PM gjr80 <[email protected]> wrote: > As this thread has drawn on I agree the solution is in the driver. I found > it had to believe that a driver could have been around for so long with an > incorrect 'pressure' being used and the issue never having come up before. > Sure enough, this thread > <https://groups.google.com/d/topic/weewx-user/hFp03F9XVH4/discussion> > from 2016 bears a remarkable similarity to the issue here. It also seems > that Tom acknowledged that the WS2813 actually outputs altimeter not > pressure as coded in the driver. Later in the thread there are suggested > changes to the driver but it gets a bit murky around some corrections that > are being applied within StdCaibrate. Seems no changes were ever made to > the driver though. Might be worthwhile for Tom or Matthew to revisit this. > > Gary > > On Saturday, 15 February 2020 14:22:07 UTC+10, ln77 wrote: >> >> OK… The “pressure” that your station is displaying is what it should be >> displaying: the ambient air pressure, correct for your altitude. In weewx, >> this is called “barometer” because that is what weather stations report for >> barometric pressure. “Altimeter” is basically the same thing; there are >> differences in exactly how it is corrected, but those differences are minor >> and can be ignored for now. The distinction between what weewx calls >> “barometer” and “pressure” is important, though, for anyone more than a few >> hundred feet above sea level. >> >> From the manual, it appears that the WS-2813 uses a simple method for >> correcting to sea level, by allowing the user to adjust a correction factor >> that is applied to the actual measured pressure until the reading matches >> some local reference barometric pressure report. This automatically also >> corrects for any errors in the pressure sensor itself, a handy bonus. >> There’s not reference in the manual to any other kind of pressure being >> reported, so it only makes sense that what it transmits via the USB >> interface is also this corrected pressure, i.e., “barometer.” But the >> WS28XX driver documentation, and as far as I can tell the code also, assume >> that the pressure reading fro the hardware is what weewx calls “pressure,” >> that is, the actual ambient pressure before correction for altitude. As >> far as I can tell, all of the WS28XX LaCrosse stations work the same way as >> yours and actually send the corrected barometer reading. Maybe because the >> LaCrosse documentation calls it “pressure,” it was mistakenly interpreted >> as raw pressure reading in the driver. >> >> The bottom line is, I’m pretty sure the issue is that the driver is >> wrong. I’m not familiar enough with that part of the weewx code to offer a >> fix, but it should be pretty simple for someone who is familiar with that >> code. >> >> -Les >> >> >> >> On 14 Feb 2020, at 19:44, Dan Blanchard <[email protected]> wrote: >> >> It is likely that I am mis-using the terms altimeter, barometer, and >> pressure. I'll clarify what I mean here. >> >> What I previously defined as 'correct' pressure is that the pressure >> reported by my station (LaCrosse WS-2813U-IT) matches the National Weather >> Service barometer reading ( >> https://forecast.weather.gov/MapClick.php?lat=47.715130000000045&lon=-116.94667999999996#.XkdkXDFKiUk). >> For example, *right now* my station is reading 30.06 pressure and the >> NWS site is reporting 30.0 barometer. Ultimately I just want my WS-2813 >> pressure reading to match the WU pressure reading ( >> https://www.wunderground.com/dashboard/pws/KIDPOSTF43). Right now it >> appears that WU is reading the weewx barometer reading. Is there a way to >> have weewx report the pressure reading to WU? >> >> My WS-2813 outputs the manually adjusted pressure in the Loop records >> (see attachment). I don't see a way to change that. Here is a link to the >> manual ( >> https://www.lacrossetechnology.com/media/catalog/product/w/s/ws-2813u-it.pdf >> ). >> >> On Friday, February 14, 2020 at 9:22:17 AM UTC-8, Andrew Milner wrote: >>> >>> I would expect you to be reporting barometer = sea level pressure which >>> is pressure adjusted for temperature and altitude because weather stations >>> always report sea level pressures. >>> >>> Is what you call 'correct' pressure the raw pressure of the instrument >>> or a pressure which you have set. Does the station output the raw pressure >>> or the manually adjusted pressure in the loop records? >>> >>> >>> >>> On Friday, 14 February 2020 18:07:15 UTC+2, Dan Blanchard wrote: >>>> >>>> Andrew, that's a good questions; let me clarify. >>>> >>>> This issue started when Weather Underground (WU) stopped showing my >>>> station on the maps. I found out that was because I was reporting an >>>> incorrect barometric 'pressure.' As I dug into the details I found that >>>> my *station >>>> *was displaying the correct pressure (29.xx) but by the time it got to >>>> WU, it was displaying the barometer reading (32.xx) from weewx. This can >>>> also be demonstrated by looking at the data displayed at >>>> /var/www/html/weewx/index.html >>>> (see attachment) so I assume that weewx is taking the pressure from my >>>> station and somehow converting it or exchanging it for barometric pressure >>>> before it gets uploaded to WU. I just want the pressure from my unit to be >>>> what is reported to WU. >>>> >>>> Side note: I've been running this station for many years on a Windows >>>> based system and it has been working fine. So I know the hardware side is >>>> working; just something different about how weewx reports pressure (or >>>> barometer, or altimiter). >>>> >>>> Does that help clarify my issue? >>>> >>>> On Friday, February 14, 2020 at 2:24:31 AM UTC-8, Andrew Milner wrote: >>>>> >>>>> I am not sure I understand what you think is wrong with the readings >>>>> of >>>>> Pressure 29.89 >>>>> Barometer 32.609 >>>>> Altimeter 32.40 >>>>> and why you believe something is wrong >>>>> >>>>> >>>>> On Friday, 14 February 2020 05:57:36 UTC+2, Dan Blanchard wrote: >>>>>> >>>>>> Altitude is 2,320 ft. and the values are in the screen shot on the >>>>>> previous post. Did you see that? >>>>>> >>>>>> On Thursday, February 13, 2020 at 7:16:11 PM UTC-8, Andrew Milner >>>>>> wrote: >>>>>>> >>>>>>> I give up - looks correct to me. >>>>>>> >>>>>>> have you run from the command line and seen the LOOP and REC data >>>>>>> weewx is receiving? >>>>>>> >>>>>>> what altitude is your station, and what values are you currently >>>>>>> getting for pressure, barometer and altimeter? >>>>>>> >>>>>>> On Thursday, 13 February 2020 22:10:08 UTC+2, Dan Blanchard wrote: >>>>>>>> >>>>>>>> I don't know, but that makes sense so I did it. I'm still not >>>>>>>> getting desired results though. >>>>>>>> >>>>>>>> On Thursday, February 13, 2020 at 9:38:55 AM UTC-8, Kevin Davis >>>>>>>> wrote: >>>>>>>>> >>>>>>>>> Do you need a space between your minus sign and the adjustment >>>>>>>>> value? >>>>>>>>> >>>>>>>>> On Thu, Feb 13, 2020 at 9:32 AM Dan Blanchard <[email protected]> >>>>>>>>> wrote: >>>>>>>>> >>>>>>>>>> Hey Andrew, will you please look at the attached screen shots and >>>>>>>>>> let me know if this looks correct? >>>>>>>>>> >>>>>>>>>> Do I need to restart (sudo /etc/init.d/weewx restart) after I >>>>>>>>>> make these changes? I have and the changes don't seem to be taking >>>>>>>>>> effect. Is there something else I need to do? >>>>>>>>>> >>>>>>>>>> With regard to the barometer and altimeter having the same >>>>>>>>>> settings; I have probably misled. They are not exactly the same but >>>>>>>>>> they >>>>>>>>>> were relatively close to each other compared to the pressure value. >>>>>>>>>> Here >>>>>>>>>> are the current readings as of now when I run sudo weewxd >>>>>>>>>> /etc/weewx/weewx.conf. >>>>>>>>>> >>>>>>>>>> pressure: 29.98 >>>>>>>>>> altimeter: 32.57 >>>>>>>>>> barometer: 32.74 >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> On Thursday, February 13, 2020 at 12:07:50 AM UTC-8, Andrew >>>>>>>>>> Milner wrote: >>>>>>>>>>> >>>>>>>>>>> If you have a LaCrosse WS28xx station then according to the >>>>>>>>>>> hardware guide the station outputs PRESSURE in weewx terminology - >>>>>>>>>>> regardless of what LaCrosse call it - and weewx should calculate >>>>>>>>>>> barometer >>>>>>>>>>> and altimeter settings. >>>>>>>>>>> >>>>>>>>>>> If pressure is incorrect then it can be adjusted as you >>>>>>>>>>> specified - by adjusting pressure (not barometer or altimeter) >>>>>>>>>>> >>>>>>>>>>> Make sure pressure is set to use hardware and barometer and >>>>>>>>>>> altimeter are set to use software. >>>>>>>>>>> >>>>>>>>>>> I am surprised barometer and altimeter are the same values - >>>>>>>>>>> have you set the station's altitude in weewx.conf, and have you >>>>>>>>>>> specified >>>>>>>>>>> software generation for the values? >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> >>>>>>>>>>> On Thursday, 13 February 2020 09:23:27 UTC+2, Dan Blanchard >>>>>>>>>>> wrote: >>>>>>>>>>>> >>>>>>>>>>>> Andrew, are you suggesting that I make a 'correction' entry >>>>>>>>>>>> under [StdCalibrate] such as barometer = barometer -2.8 assuming >>>>>>>>>>>> that I am >>>>>>>>>>>> getting a pressure reading of 30.13 and Barometer and ALtitude >>>>>>>>>>>> readings of >>>>>>>>>>>> 32.93? >>>>>>>>>>>> >>>>>>>>>>>> (see attached screenshot) >>>>>>>>>>>> >>>>>>>>>>>> On Wednesday, February 12, 2020 at 7:42:08 PM UTC-8, Andrew >>>>>>>>>>>> Milner wrote: >>>>>>>>>>>>> >>>>>>>>>>>>> 1. use stdcalibrate section of weewx.conf >>>>>>>>>>>>> http://weewx.com/docs/usersguide.htm#StdCalibrate >>>>>>>>>>>>> 2. FO station = Fine Offset weather station >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> >>>>>>>>>>>>> On Wednesday, 12 February 2020 22:15:48 UTC+2, Dan Blanchard >>>>>>>>>>>>> wrote: >>>>>>>>>>>>>> >>>>>>>>>>>>>> Andrew, how do I calibrate the pressure in weewx? Also, >>>>>>>>>>>>>> what's a FO station? >>>>>>>>>>>>>> >>>>>>>>>>>>>> On Tuesday, February 11, 2020 at 8:01:08 PM UTC-8, Andrew >>>>>>>>>>>>>> Milner wrote: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> check that the absolute pressure is correct - I have had a >>>>>>>>>>>>>>> FO station which had a dodgy pressure sensor before now. >>>>>>>>>>>>>>> Calibrating >>>>>>>>>>>>>>> pressure in weewx solved it. >>>>>>>>>>>>>>> >>>>>>>>>>>>>> >>>>>>>>>> -- >>>>>>>>>> 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/08c79655-b1af-4134-9a2b-82a4f52f051f%40googlegroups.com >>>>>>>>>> <https://groups.google.com/d/msgid/weewx-user/08c79655-b1af-4134-9a2b-82a4f52f051f%40googlegroups.com?utm_medium=email&utm_source=footer> >>>>>>>>>> . >>>>>>>>>> >>>>>>>>> >> -- >> 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/a24bec68-9459-43f4-8765-933c0c1f2490%40googlegroups.com >> <https://groups.google.com/d/msgid/weewx-user/a24bec68-9459-43f4-8765-933c0c1f2490%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> >> >> -- > 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/9184cd46-6123-4de2-8990-dfd60576eb05%40googlegroups.com > <https://groups.google.com/d/msgid/weewx-user/9184cd46-6123-4de2-8990-dfd60576eb05%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. 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