[Xastir] Own Weather Reports

[Clay Jackson]

I just took a look - it looks like Xastir is accumulating the per hour
totals and then using those; and, since I've been running for less than
24 hours, that's why there are no numbers anywhere else - makes
sense....

I'll post something tomorrow if it's not what I expect.....

Clay


On Sat, 2005-02-05 at 19:48 -0600, Gerry Creager N5JXS wrote:
> I'll try to wander thru the code tonight, too, plus or minus a dtabase 
> problem that's kicking my rear for Mesonet.
> 
> Curt Mills wrote:
> > On Sat, 5 Feb 2005, Clay Jackson wrote:
> > 
> > 
> >>I'm having some problems wWeather reports.  I've got a Davis WMII,
> >>w/meteo capturing the data, and db2APRS sending the data from a
> >>different system to Xastir.  I've hacked db2APRS a bit, to make it
> >>conform to the APRS 1.1 spec for positionless weather data -  so, it's
> >>sending packets that look like this:
> >>
> >>_0205101900c161s001g005t040r000p009P008h88b10225xDvs
> > 
> > 
> > I should have thought about this from some of your earlier messages
> > about it:  Positionless weather is considered to be an abomination
> > by a lot of people.  I think it was added to the spec merely because
> > one of the weather stations was able to put out that format
> > directly.  Most people that have commented on this have suggested
> > that some other weather format be used normally that includes the
> > position of the weather station along with each packet.  That way
> > you don't have to combine posits with WX packets in order to have a
> > complete picture.
> 
> Positionless weather reports are EVIL.  Next question?
> 
> >>According to the spec r000 is rain in the last hour, p009 is rain in the
> >>last 24 hours and P008 is rain since midnite.  HOWEVER, Xastir is
> >>reporting total rain of 0.09 and 0.00 for the other rain values.  The
> >>other data points (wind, temp, humidity) all look OK.
> > 
> > 
> > Xastir calculates this stuff itself as I recall.  I've been into
> > that code more than once, and rewrote part of it, but it's been long
> > enough that I don't remember all the details anymore.  As I recall
> > though Xastir ignores the values for 24-hours and since-midnight
> > that are sent by the weather station and computes them itself.  If
> > you haven't run Xastir connected to the WX station that long, the
> > values won't match the values that the WX station might be telling
> > you.
> 
> The spec had a lot of input from some real content experts.  This didn't 
> stop 'em from codifying what the s/w authors of the day THOUGHT should 
> be there.  That's why Xastir calculates it itself: to do it better than 
> the spec thinks it should be.
> 
> >>Also, I'm not seeing anything in the Dew Point, High Wind, Wind
> >>Chill/Heat Index and Hi and Low Temps - is Xastir expecting those from
> >>the Weather Station, or calculating them?
> > 
> > 
> > I'd have to go look at the code.  I think most things come from the
> > weather station, but of course most things aren't put out by most
> > weather stations, so they don't ever get filled in.
> 
> 
> In general, humidity is easy to measure with an electronic instrument, 
> while dew point is not (but a sling psychromoeter is not too hard for a 
> human, who then calculates humidity usually using tables, and ignorant 
> of the differential equations that go into the overall calculation... 
> but that's not important right now).  FindU uses a table lookup to get 
> the Td.  If the values for peak wind, gusts, etc are reported, it uses 
> 'em, as I recall.Heat Index and Wind Chill are trivial to calculate. 
> Xastir, really, should be accounting for high/low temps, IMNSHO.
> 
> gerry