[Xastir] Xastir and Ultimeter weather station

[Rick Green]

> Gerry Creager <gerry.creager at tamu.edu> wrote: Matt Werner wrote:
>> I have a 2000 but currently have the wind sensor disconnected (it's
>> under repair).
>>
>> It would be nice to have the ability to tell xastir which sensors to
>> report and which to ignore.  Peet's data structure naturally doesn't
>> change it's format when the sensors are unplugged, it just reports no
>> data for them.
>
> Having spent a fair bit of time w/ Davis yesterday getting them to
> update their windows s/w for APRS-WX/CWOP... if I can find Peet at the
> American Meteorological Society meeting, I've some requests for them,
> too! And you just raised a key one.  We should have a standard value for
> *Missing Data* such as, -99999 (which is, in fact, one such well
> recognized value in the meteorological community).
>
>> The difference between 0 and 'no data' is significant but xastir
>> doesn't recognize it.


The code currently appears to expect a string of dashes '--' in fields to 
indicate missing data.  Here's a snippet from wx.c:

     // 006B 00 58
     // 00A4 00 46 01FF 380E 2755 02C1 03E8 ---- 0052 04D7    0001 007BM
     // ^       ^  ^    ^    ^         ^                      ^
     // 0       6  8    12   16        24                     40
     /* wind speed */
     if (data[0] != '-') { // '-' signifies invalid data
         substr(temp_data1,(char *)data,4);

...but it doesn't seem to be uniformly implemented, and the ultimeter 
outputs zeroes for many missing sensors.

-- 
Rick Green, N8BJX

"Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety."
                                   -Benjamin Franklin