Indeed I suspect something has changed. The start of my archive has windDir and windGustDir that are all multiples of 22.5. However, the most recent portion of my archive has values all over the place. Maybe Tom might know what changed otherwise it will have to wait until I have free time to investigate. Two things that come to mind though, were some changes to the vantage driver around 3.7.0 (I think) and also a change to wring whatever we could out of the accumulators (also around 3.7.0 I think). Maybe be nothing to do with it but two areas of change that could be relevant.
Gary On Friday, 10 August 2018 12:50:35 UTC+10, gjr80 wrote: > > Well that is interesting, according to the Davis Serial Communications > Reference Manual > <https://www.davisinstruments.com/support/weather/download/VantageSerialProtocolDocs_v261.pdf> > > the archive record format tables on pages 31-33 say that prevailing wind > direction (and high wind direction - read windgustDir) is provided as a > code representing one of the 16 compass points. And when you use hardware > record generation WeeWX uses the archive record from the station. Would > seem something is polluting the hardware archive record. > > Gary > > On Friday, 10 August 2018 12:36:49 UTC+10, Andrew Milner wrote: >> >> I am now confused Gary >> >> Here is my archive and also my weewx.conf. From your post I should only >> have the 16 cardinal points, but don't >> >> >> >> On Friday, 10 August 2018 02:14:05 UTC+3, gjr80 wrote: >>> >>> Archive records generated by Davis hardware use a single byte for wind >>> direction (both windDir and windGustDir) with 4 bits being used to >>> represent 16 points of the compass ie N, NNE, NE etc. Loop packets on the >>> other hand use provide a wind direction in two bytes that provides integer >>> degrees from 1 to 360 degrees. >>> >>> So the bottom line is that a system using a Davis station using hardware >>> record generation will only see discrete 16 point compass values for any >>> point in time windDir (and windgustDir) tags (aggregates that average >>> over a time or min/max values that have been based on loop data will/may >>> show value other than the 16 compass point equivalents). Of course if you >>> decide to use software record generation then WeeWX will calculate the wind >>> directions based on accumulated loop data and that will result in values >>> other than the 16 compass point equivalents. >>> >>> Only seeing degree equivalents of the 16 compass points for windDir/ >>> windGustDir from my Davis station always seemed like a shortcoming to >>> me, but when you think of windDir and windGustDir as averages over an >>> archive period (say 5 minutes) it makes much more sense. >>> >>> Gary >>> >> -- 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 weewx-user+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
