WX.txt 820  USING APRS IN WEATHER AND SKYWARN APPLICATIONS

New in 809  Now supports COUNTY WX Warnings.  See sections below
New in 796  Supports HC/TS winds to the DOT symbol too for predicts
New in 793  *****  All new WX formats not Backward compatible *****
              WX-GETmetar can load METAR data from a file into P-LIST.
New in 78b  File-Print will log new data to a printer and on the P-LIST,
              Just-Print-WX will print a file or page of all WX data
              Fixes receipt of remote Ultimeter WX data for some units

OVERVIEW:  APRS is an ideal tool for reporting weather conditions via 
packet.  With the optional $14 WX registration, APRS will accept and 
transmit serial data from the PEET Bros ULTIMETER or DAVIS home weather 
stations.  You can even mount an ULTIMETER remotely with only a TNC and 
Radio to report and plot conditions.   APRS is idealy suited for SKYWARN 
with the following features:

 MAP DISPLAY - Shows the location of all reporting stations and their
     WX conditions.  Can also show the location of DOZENS of other 
     WX symbols or objects... WX-WINDflow displays Wind contours.
     
 WX SYMBOLS - There are dozens of WX symbols such as TStorms, Hail, 
     Tornados, etc in APRS.  Any station may place a storm or other WX 
     object on everyone's map displays.  It will automatically move if
     it is given a course and speed.
     
 WX WARNINGS - You can mark large areas with either rectangles, circles, 
     triangles, or lines using the OBJECTS-AREA symbols.  New in 809, 
     Whole counties will change color based on WX Warnings transmitted 
     by specially formatted APRS Messages.  This display is automatic 
     unless toggled off with the WX-DISPLAYS-NO-Counties command.
     See the COUNTY WARNINGS section below.

 WEATHER ONLY - The JUST-WX command for a temporary display of only WX 
     stations on the map or P-List.  Use the WX-JUST-WX-ALWAYS command 
     to lock this feature on and off.  The N-NEXT command cycles through 
     each WX station in turn with a circle on the map and displays its 
     wx conditions at the top of the screen.  

 TROPICAL STORM WINDS - For tropical storms a special COMMENT format 
     will cause APRS to color huricanes red, tropical storms yellow 
     and depressions blue. It will also show the radius of the winds with 
     colored circles.  These wind radii are offset in the direction of 
     the danger quadrant proportional to the storm speed of advance.

     DDHHMM/LAT/LONG@CSE/SPD/TS/www^GGG/ppp>RRR&rrr

     Where @   is the symbol for a Huricane 
           /   is the symbol for a predicted posit
           CSE is direction of movement         
           SPD is speed of movement
           TS, HC and TD are types of storm
           www is sustained wind speed
           GGG is peak wind gusts
           ppp is central pressure
           RRR is radius of Hurrican winds
           rrr is radius of TS winds
 
 DEAD RECKONING -  APRS dead-reckons moving objects, so the symbol on the 
 map is presented where it SHOULD be, NOT where it was when first reported.  
 To hook one of these objects on the map, you must hook the little gray 
 circle which marks the position of the actual report, and not the symbol 
 itself.  After two hours with no update, the symbol fades to dark gray.

 NWS STATION PLOTTING - Hit MAPS-OVERLAYS-NWS to see all NWS Sites

 METAR BULLETINS - Suggested by KD4UYR in FLorida, this feature parses 
     NWS METAR bulletins and plots the WX data on the map.  
     
 WX-DISPLAY - You may select to have the WX conditions displayed 
     by each WX station instead of the callsign.  There are 3 formats.  
           WX-DISP-TIME shows the TIME
           WX-DISP-TEMP shows Temperature
           WX-DISP-BARO SHows Baro and rain
           WX-DISP-WIND Shows winds

 OPERATOR MESSAGES - The Point-to-point message capability can be used
     for operator to operator messages and alerts.  With FILE-PRINT
     enabled, these messages and WX reports can be scrolled to the printer.
       

 STATUS - In addition to weather data included in position reports, the 
     station STATUS packet is also available for additional info.  These 
     STATUS packets can be reviewed on the LATEST display.  
     
 BULLETINS -  Bulletins are an alerting mechanism for all stations.  
     
 VOICE REPORTS -  Even non-packet voice stations making a weather report 
     can be placed on the map (like an object) by another APRS packet 
     operator.  His station will appear in purple showing that his report
     has been placed there by another station.


COUNTY WARNINGS - This was pioneered by the Sprouls and causes APRS to
color in counties based on NWS Warnings in effect.  Hit the usual 
label zoom keys ] and [ to see the county name if needed.  The 
formats for these warnings are a message sent to the APRS address of
NWS-XXXXX as shown below.  These messages accumulate on the APRSdos
TRAFFIC page where they drive the coloring algorithm.

    NWS-WARN :exptime,type,c1,c2,c3,c4,c5, (where c1-c5 are counties)
    NWS-WATCH:exptime,type,c1,c2,c3,c4,c5,
    NWS-ADVIS:exptime,type,c1,c2,c3,c4,c5,
    NWS-TEST :exptime,type,c1,c2,c3,c4,c5, (trailing comma is needed)
    NWS-CANCL:type,c1,c2,c3,c4,c5,

Where: exptime - is the Expiration time in the usual DDHHMM format
       type    - is free text of the type of warning
       c1 - c5 - 1 to 5 counties truncated to 9 bytes or less each

NOTE:  If the type of warning is longer than 10 bytes, then only include
4 counties per line to prevent truncation by APRS on receipt.

In APRSdos, maps with county map labels of the form SS_COUNTY which  
match the counties in the C1 to C5 fields above will change color.
These fields are limited to 9 characters according to these rules:

    1. SS_ is the state abbreviation
    2. Next 6 chars must be first six chars of County name, omit
       spaces and abbreviate SAINT to ST, PRINCE to PR, etc...
    
    See COUNTIES.TXT for details in making the labels for your maps.
Since there is not room for all 3000 Counties in my larger regional
and USA maps, in these maps, the entire state will color based on the
SS_ formats.  Or you can trigger a whole state with SS_STATE.


NATIONAL WEATHER SERVICE HOURLY METAR BULLETINS

     Based on work by KD4UYR in Clearwater FL, the MAPS-OVERLAY-NWS command 
searches the NWSposns.POS file and temporarily displays all NWS stations 
within the boundaries of the current APRS map display (up to 250 miles).  
You are given the option of a one-time map overlay or to add the sites to 
your P-LIST.

     The WX-GET-METAR command is used for loading a file of NWS METAR
reports.  This file can be obtained from most of the commercial data
servers or some BBS's, or on the internet at:  

     http://weather.noaa.gov/weather/metar/shtml
   
     APRS will scan the NWS METAR file looking for each station that you 
have  on your APRS P-LIST.  For each match, it will parse the Winds, 
temperature, dew point and barometric pressure onto the P-list.  It 
takes the remainder of the report and places it on the L-list.  The time 
of the entries in the P and L-list will be the time of the NWS report 
(in local time).  The date is assumed to be the current date.  

Once the data is loaded, you can uplink selected stations to the APRS net 
as desired.  Be considerate, though, and not overload the channel.
Once everyone on the net sees the reports, the uplinking station should
consider Quitting the uplink in order to reduce QRM.

DEMONSTRATION:  To see how APRS works in a SKYWARN or other reporting net,
load the backup file SKYWARN.BK using the FILES-LOAD command.   To 
demonstrate the NWS capability, center your map on Illinois at the 128 
mile range, enter the MAP-OVERLAY-NWS command and select the Add option 
to add them to your P-List.  Next, enter the WX-GETmetar command to load 
the sample METAR data file.  Look at the P and L-lists to see what is 
going on...

METRIC MEASUREMENTS:  You may select wind speed in KPH and temperature in 
Celsius by toggling the WX-METRIC command.  This will force the WX display 
at the top of the screen to display metric and will cause the manual WX
entry values to be accepted in Metric.  You can make this permanent, by 
saving a CONFIG file.  The on-air APRS WX protocols, however, still 
will be in MPH and F.  Also, the ALARMS are compared to MPH and F values.

WX ALARMS:  If a WX report comes in that exceeds your alarm values, the
station is plotted in RED and an ALARM sounds.  The alarms are WIND, TEMP,
and RAIN.  These settings can be used to warn of the passing of a warm or
a cold front.  Use APRS and these alarms to make an almost un-attended
SKYWARN network!  Install an APRS computer at the NWS site, and let the
NWS operators set the alarm levels.  Then without transmitting a single
packet (there is rarely a licensed HAM on the premises) the APRS screen
will show SKYWARN data and where the alarm conditions are!

CLEARING ALARMS:  When an alarm occurs, the station is drawn in RED and
the map is re-drawn to center on that station.  Also, the station is
marked on the P-list with the ALARM marker.  TO clear the alarm, simply
hook the station on the map, and then UNhook it (hit ENTER twice), or
use the WX-ALARMS-CLEAR command.  To clear the A on the P-list, hook the
station and hit the A key.  Normally, the ALARM on the P-list will only
sound if that station MOVES.  Since a WX station should not move, there
is really no problem in leaving the A on the Plist until convenient to
remove it.

WEATHER WARNINGS AND WATCH BOXES:  You can use the OBJ-AREA-LINE command
to draw a box plus-or-minus X miles from a line between points A and B.
The line and width are perfect for WATCH and WARNING boxes.  If baseline
lengths longer than 400 miles are needed you must combine two or more
boxes.  Use the normal OBJ-AREA-LINE command and indicate the +/- offset
of the sidelines in a 3 digit number of Miles enclosed in braces {075}
anywhere in the COMMENTS field.

HOME WEATHER STATION INTERFACE:  With the optional $14 WX registration, 
APRS inserts the ULTIMETER or DAVIS conditions in your position report
for unattended weather reporting.  ULTIMETERS that output data with a *
output wind in MPH and those with a # in KPH.  APRS averages the wind 
value over the last 4 samples, so the default rate is every 15 seconds
to yield a running 1 minute average.

RAIN VALUES:  Rain is counted in increments of 0.1 or 0.01 inch or 1mm.  
but reports all values in 0.01 inches over the air.  Since raw rain 
counts have no meaning without knowing when they were last reset, APRS 
only compares the difference in rain for the last hour (rXXX) and the 
precipitation in the last 24 hours (pXXX).  A reading of r123 means 1.23 
inches fell in the last hour.  After 60 minutes, this value will return 
to zero.  A reading of p164 means 1.64 inches have fallen since the same 
hour yesterday.  For REMOTE ULTIMETERS with only a TNC and no PC, 
the P value means rain since MIDNIGHT and an uppercase Pxxx is used.  
Also since there is no RAIN per hour value, that field is replaced with 
the raw rain counter #xxxx.

FORMATS:  The following formats are the way that APRS re-formats the data 
from the attached WX unit and transmits the data on the air.  For remote
Ultimters, where there is no PC, and the TNC is just transmitting the raw
Ultimeter format, then these formats represent the way that APRS parses and
displays the received data on the P-LIST.  

   _CSE/SPDtXXXrXXXpXXXgXXXdU-II        Original U-II auto
   _CSE/SPDtXXX#XXXU2r                  Original U-II remote
   _CSE/SPDtXXXrXXXpXXXbXXXXhXXgXXXdDvs  Davis WX station
   _CSE/SPDtXXXrXXXpXXXbXXXXhXXgXXXdU2k  U-500/2000 with APRS
   _CSE/SPDtXXXPXXXbXXXXhXXgXXXU2kr      Remote Ultimeter Logger
   _CSE/SPDtXXX#XXXbXXXXhXXgXXXUpkm      Remote Ultimeter Pkt Mode

   _CSE/SPDgXXXtXXXrXXXpXXXPXXXhXXbXXXXX%type NEW FORMAT APRS793 June 97
                                              NOT BACKWARD COMPATIBLE

Where:        CSE/SPD is wind direction and sustained 1 minute speed
              t is in degrees F
              r is Rain per last 60 minutes
              p is precipitation per last 24 hours (sliding 24 hour window)
              P is precip per last 24 hours since midnight
              s is snow
              b is Baro in tenths of a mb 
              h is humidity in percent.  00=100
              g is Gust (peak winds in last 5 minutes)
              # is the raw rain counter for remote WX stations
                   See notes on remotes below
              % shows software type d=Dos, m=Mac, w=Win, etc
              type shows type of WX instrument
              

With the WX interface enabled, the normal APRS decaying of position/wx
reports still holds as long as nothing changes (except the wind).  This
way, redundant WX reports do not cloud the channel.  If any other WX
value changes, then the period is reset to the alt-SETUP-POSrate value.
The WX-WIND command can be used to set a Wind threshold which will force
a WX report whenever the wind is above that threshold.   

WX PERIOD:  APRS decays to 10,20,or 30 minute rates depending on the 
number of digipeaters.  For a weather station, you should change the 
MaxPeriod to maybe 10 minutes or so using a text editor in your 
CFIGxxx.APR file.  There it is expressed in seconds.  Of course, a
WX/position report will be transmitted by the APRS station at anytime,
in response to an APRS or WX query.

ULTIMETER INTERFACE CABLE:  Peet Bros sells an interface cable with a
DB-25 connector to RJ-11.  Since the U-II has no negative supply, a 5 K 
pulldown resistor is added to the DB-25 connector between Pins 2 and 3.  
This uses the -5 or -12 volts on the unused TXD line to bias the RXD 
line.  You can use a common phone line plug for their serial output.
I found the data on the green while using the black wire as ground.  
If your connector was crimped on backwards, red is data and yellow is 
ground.  The Peet Bros cable includes transient protection and RF 
filtering to protect your computer as well as providing the bias resistor.   
Remember, the annemometer is like an antenna, high in the air.  It can 
radiate RFI and take lightening charges...  The U-2000 is directly 
RS-232 and needs no pull down resistor.  Be sure the U-500/2000 is in 
DATA-LOGGER mode.

DAVIS INTERFACE:  You must have the DAVIS Weather Link serial interface
option before your Davis station will output serial data.  Simply connect 
their connector to your PC. You MUST use the APRS alt-SETUP-OTHER-AGL 
command to set your average ground level.  This converts your baramoter 
readings to their equivalent value at sea level...  Your objective is to
find an exact AGL that will result in your BARO readings matching the 
readings on your instrument or local NWS.  THis AGL will probably NOT be
your true AGL.

SAVE A COMM PORT!  You can use a simple 89 cent switch to allow other
devices to share a single COMM port with your WX station.  Since the WX 
stations only use ONE pin and GROUND, simply add them to your MODEM
cable with a simple SPDT switch as follows:

       ULTIMETER-II   >---------*--------*  sw1
                                |        <----*--------------> RXD
       MODEM   }      >------------------*
         or    }                |
       other   }                *-----/\/\/\/\-------*
       serial  }                        5.6k         |
       device  }      <------------------------------*-------< TXD
               }      * * * -----------------------------* * * other pins
               }      *--------------------------------------* GND

Actually, you can wire this to any serial device that you do NOT use while
running APRS.  I chose my MODEM that is on COM2.  Note the series resistor
as mentioned in the text to provide the -V pull-down for the U-II output.

REMOTE ULTIMETER OPERATION:  Only the Ultimeters from Peet Bros can be used
as remote WX stations (using only the WX station, a TNC and a radio).  This
is because they output continuous data withing needing a PC to interrogate
it periodicaly.  There are two ways to time the transmission of this data
for the packet channel depeneding on what Ultimeter you are using.  We call
these PACKET mode or DATA LOGGER mode:

DATA LOGGER MODE (GPS mode):
  
  U-II - These units output 14 bytes continuously beginnning with * or #
  U-2000 (old) - These units output 44,48,or 52 bytes beginning with !!

For the DATA LOGGER mode, the TNC must do the scheduling of packets just 
like the TNC does for continuous GPS data.  That is why this mode is often
called the GPS mode even though GPS has nothing to do withe Weather.  You
must program your TNC to think that the WX data is GPS data.  Simply 
program the stand-alone-TNC to recognize the #, * or !! instead of the 
usual $GPRMC data typically used for GPS.  Then set the timing for each 
transmission to be about once every 5 minutes.  Be sure to SET ECHO off if
your ULTIMETER-II uses a resistor on the TXD line to bias the RXD line!
(Otherwise you will echo all heard packets back onto the channel!  KD4GOE 
figured that one out!).

PACKET MODE :
  U-500 - Outputs 44,48,or 52 bytes beginning with $ULTW

This mode was designed for APRS packet since the WX unit only outputs
a single data line every 5 minutes.  Since it is already timed to once
every 5 minutes, all the TNC has to do is be in UI CONVERSE mode and it
will send the packet.  Be sure to use a TNC that can be configured to  
power-up in UI-CONVERSE.  Try UIMODE or PMode-CONV depending on your
TNC.  ALso you must set LFIgnore to ON so that the LF after the CR is 
not transmitted..  Since the Kantronics TNC's do not have LFIGNORE,
you must set SENDPAC to $0A (linefeed) and set CR off!  If there are
dozens of REMOTE U-500's, hopefully their clocks are staggered enough
that they wont all transmit at EXACTLY the same time. 

CAUTION:  Only U-500's and only U-2000's manufactured after April 97
should be used in packet mode.  U-2000's prior to that date will not
show wind in the packet mode.

                   
WX POSITION:  In both cases, you must put the unit's POSIT in the BText
using the "_" WX symbol.  This way the TNC transmits two packets, one
is a BText WX posit with no WX data, and the other is raw WX data with 
no posit!  APRS cannot display the WX on the map until it has received 
a WX posit beacon.  So, set the beacon to go about once every 20 minutes.  
Once the posit is received it will be displayed as a Blue dot unless the
site is also acting as a WIDE-RELAY digipeater, and it will show GREEN if 
the delimiter between the LAT/LONG is set to a backslash instead of the 
usual forward slash.

WX LOGGING:  Use the WX-LOG command to turn WX-LOGging on and off.  It will
show on the control panel when on.  If ON, then on-air reports are saved
when received every 10 minutes or so, and your own report will be saved at
the rate set by the Set-Pos-Rate command.

DIRECTION FINDING:  Since your station can only send one position report,  
If you use the BEAMHEADING command to enter a beam heading on a Fox or 
Jammer, then your WX station is disabled.  To restore your WX station, 
restart the program.

