WX.txt 7.4    USING APRS IN WEATHER AND SKYWARN APPLICATIONS

New in 7.4    Compatibiliy with the new ULTIMETER-2000

OVERVIEW:  The Automatic Packet Reporting System (APRS) is an ideal tool for
reporting weather conditions via packet.  The system is compatible with both
human entry as well as automatic weather station entry of weather conditions.
With the optional $9 WX registration, APRS will accept serial data
from the ULTIMETER-II home weather station.  With this connection, your wind
conditions, temperature and optionally rain information are all automatically
inserted into your position/weather report packet.  You can even mount an
Ultimeter-II remotely with only a TNC and Radio, and have it periodically
report the remote weather conditions.

Using APRS, current conditions at any station and the station's position are
broadcast to all stations on the net in a periodic fashion.  There are several
capabilities of APRS that are directly applicable to SKYWARN:

 MAP DISPLAY - Shows the location of all reporting stations, their wind
     speed and direction.  Can also show the location of other objects, such
     as reports of TStorms, Hail, Tornados, etc.  You can also mark large areas
     with either a rectangle, circle, triangle, or lines.  Use the OBJECTS-AREA
     symbol.  Typically, use blue for thunderstorms, and red for tornados.

 WEATHER ONLY - Using the J command, Just weather stations can be displayed on
     the map or P-List to eliminate the clutter of other packet stations.
     There is a WEATHER menu of commands, and the APRS N key will cycle through
     each APRS weather station in turn and display the weather conditions for
     each one in a box on top of the screen.  The location of the displayed
     station is highlighted with a blue circle.  Whenever a new report comes
     in from the selected station, the weather window is automatically updated.

 REPORT BROADCASTS - The individual station weather conditions can be manually
     entered with the WX-ENTER command or automatically using the optional
     APRS registration to enable the ULTIMETER-II serial interface.  These
     reports are typically broadcast every 9 minutes.  The report is also
     available at anytime if an APRS user sends the WX station an APRS Query,
     or the all-call WX query.

 STORM/HURRICANE TRACKING - Any station may place a storm or other object on
     his map, and the same symbol will be transmitted to all other stations
     in the net.  If the course and speed of advance of the storm is included
     in the report, then it will automatically be dead-reckoned on all
     screens until the next update.  Any station can update the location as
     information becomes available.  The updating station will overwrite all
     posits in the net and will become the new reporting station.  This
     prevents duplicate reporting and eliminates dependency on the original
     posting station.  For Huricanes and tropical storms/depressions, if the
     following COMMENT format is used, APRS will color the storm RED for
     huricanes, Yellow for tropical storms and BLUE for depressions.  It will
     also show the radius of the winds with colored circles.

     DDHHMM/LAT/LONG@CSE/SPD/TS/www^GGG/ppp>RRR&rrr
                             |   |   |   |   |   * - - - - Radius of TS wnds
                             |   |   |   |   * - - - - - - Radius of HC wnds
                             |   |   |   * - - - - - - - - Cenral Pressure
                             |   |   * - - - - - - - - - - Gusts
                             |   * - - - - - - - - - - - - Sustained winds
                             * - - - - - - - - - - - - - - HC, TS, or TD

 NOTE:  APRS dead-reckons moving objects in time, so the symbol on the map is
     presented where it SHOULD be, but 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.

 NATIONAL WEATHER SERVICE DISPLAY - Suggested by KD4UYR in FLorida, this
     feature parses NWS hourly bulletins (SA's) and plots the WX data on
     the map.   NWS sites now have a different symbol from home WX sites.
  
 AUTO-HURICANE TRACKING - At the suggestion of KR4US i wrote NWSPARSE.bas which
     will parse incomming NWS bulletins on one COM port, and output APRS storm
     symbols and tracks via a TNC on the other COM port.  Using a dedicated
     old XT PC, this system can automatically inject WX storms into APRS nets!

 OPERATOR MESSAGES - The Point-to-point message capability can be used
     for operator to operator messages and alerts.

 COMMENTS   -  Transmitted along with each position report, there is a
     short comment field which can be used to report weather conditions,
     station status, intentions or other broadcast type information.


SKYWARN APPLICATION:   APRS displays all Wx reporting stations in blue along
with wind conditions.  Note that APRS only recognizes 360 as North, and not
000, which means there is no wind direction available.  The comment field can
be used for a variety of free-format weather reports which can be tailored to
the conditions at any time.  APRS does not update the time field on manual
reports but does transmit current time using the ULTIMETER-II interface.

    In addition to weather data included in position reports, the station
Beacon Text is also available for broadcasting additional amplifying info.
These beacons can be reviewed on the LATEST display.  The APRS BULLETIN
feature is very powerful as an alerting mechanism to all stations on the net.
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
similar to any other APRS weather station, except that his report will include
a marker indicating that he was manually placed on the map by another operator.


NATIONAL WEATHER SERVICE HOURLY BULLETINS

     Based on work by KD4UYR in Clearwater FL, this feature first uses the
Add-NWS-to-PList command to search the NWSposns.DAT file for all NWS stations
within the boundaries of the current APRS map display (up to a maximum of 250
miles).  The database is only accurate to the nearest minute (mile).  All NWS
sites are given a unique WX symbol (Blue dot with a circle) and added to the
PList.  To avoid cluttering up your PList, you can use the SHOW-NWS-SITES
command to temporarily display the stations...

     The LOAD-WX-DATA command is used for loading the NWS data if available
on your PC in a text file containing the downloaded NWS hourly reports.  This
file can be obtained from most of the commercial data servers or some BBS's.
On the internet, use GOPHER to wx.atmos.uiuc.edu to obtain the data.
APRS will then scan through the NWS bulletin file looking for each station
that you have on your APRS P-LIST.  If it finds a matching NWS bulletin, it
will parse out the Wind speed/direction, the temperature and dew point and
the barometric pressure and place these on the P-list.  THen it will take the
remainder of the report and place it in the L-list so that you can see the raw
data which includes other notes about cloud cover and special conditions.  In
both cases, the time of the entry 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.

     Unfortunately, these reports were designed for human reading and are also
generated by hand at all the NWS sites.  There are frequently errors or in-
properly formatted reports.  If APRS can not make sense out of the report, it
indicates with "garbled report" on the P-list.  Once you have the display you
like, you can select stations on the P-list for uplink to the 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, and then Killing them when they are no longer
valid.  See details on the KILL command in HELP.txt.

DEMONSTRATION:  To see how APRS works in a SKYWARN or other reporting net,
load the backup file SKYWARN.BK using the FILES-LOAD command.  Use the P
command to pull up the position/weather reports and notice the format for
W3ADO.  That station is reporting the wind and temperature automatically
using the optional ULTIMETER-II interface.  To demonstrate the NWS capability,
center your map on FLorida at the 128 mile range enter the WEATHER-GET_NWS_
SITES command.  Once all the NWS stations appear on the map, then enter
the WEATHER-LOAD_WX_FILE command to load the sample NWS data file provided by
KD4UYR.  Look at the P and L-lists to see what is going on...


KPH and CELSIUS:  You may select to display wind speed in KPH and temperature
in degrees Celsius.  You enable this by doing a manual WX report entry and
answer with EITHER K for KPH or C for Celsius.  From then on, the WX display
at the top of the screen will display in those units.  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 will be compared to MPH and F
values.

WX ALARMS:  If a WX report comes in that exceeds your preset 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 the ENTER key 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:  New in version 6.8c, 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 100 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.

ULTIMETER-II INTERFACE:  To permit automatic weather station reporting, APRS
includes an optional serial interface to the ULTIMETER-II home weather station.
(I offered to develop one for DAVIS instruments, but they call their data
propriatary and will not share it with HAMS).  The optional APRS U-II routine
is activated by a separate validation number ($9).  Once activated, APRS
inserts the ULTIMETER-II conditions in your position report automatically for
unattended weather reporting.  The ultimeter comes in two configurations which
are not distinguishable by the user.  One version ouputs wind in MPH and the
other in KPH regardless of what is set for the U-II front panel display.  APRS
detects the difference  by the beginning character of the report.  A * means
MPH and a # means KPH.  APRS converts the # units to MPH by dividing by 1.6.
Also APRS averages the wind value over the last 4 samples.  Thats why the
display UPDATE period is set to 15 seconds, so that the resulting wind speed
transmitted represents a 1 minute average.

RAIN VALUES:  In the Ultimeter-II, two rain count accumulators are incremented
every time the rain gage clicks (0.1 inch unless special ordered for 0.01).
APRS asks you which gage you have and converts both to 0.01 inches on the air.
Since the raw U-II rain values have no meaning without knowing when they
were last reset, APRS only transmits the difference in rain for the last 60
minutes (/Rxxx) and the last 24 hours (/Pxxx).  A reading of /R120 means that 
1.2 inches fell in the last hour, R123 means 1.23 inches.  After 60 minutes, 
this value will return to zero.  A reading of /P164 means that 1.64 inches 
have fallen since the same hour yesterday.  For a REMOTE U-2000, this P value
means rain since MIDNIGHT.  Also since there is no RAIN per hour value, that
field is replaced with the /Cxxx change in Barometric pressure.  For a REMOTE 
U-II, the Raw rain count is displayed as #nnnn and there is no P value.   
There are four possible formats for an ULTIMETER depending on whether it is 
local or remote:  (also see PROTOCOL.txt)

   .../LAT/LONG_CSE/SPD/Txxx/Rxxx/Pxxx/U-IIauto      Original U-II w APRS
                CSE/SPD/Txxx#xxxx/P.../U-IIrmte      Original U-II remote
                CSE/SPD/Txxx/Rxxx/Pxxx/Bxxx/Hxxx/U2a U-2000 with APRS
                CSE/SPD/Txxx/Cxxx/Pxxx/Bxxx/Hxxx/U2r U-2000 remote
                             R...      B.../H...     devices not connected

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 value, 
Position, temperature, rain, barometric pressure, or comments change, 
then the periodicity is reset to the value set in the alt-SETUP-POSrate 
command.  Since the wind is the most changing parameter, the WX-WIND 
command can be used to set a Wind threshold.  Whenever the wind is above 
that threshold, the reporting period is also reset to the POSrate value.  
Nominally, you might want to set the POSrate value to about 4 minutes or 
so.  This way, during changing WX conditions, or wind above your 
threshold, the WX is reported every 4 minutes.  Otherwise, the period
rapidly decays back to the maximum APRS delay period (default is 20 
minutes).  For a weather station, you might want to change this MaxPeriod 
to maybe 10 minutes or so.  Use a text editor to change this value 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.

SERIAL INTERFACE CABLE:  Peet Bros sells a serial interface cable with a 
DB-25 connector to RJ-11.  (Note, this is a DB-25, not a DB-9).  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 
your TXD line to bias the RXD line.  When I plugged in a standard phone 
line connector to the U-II serial data output (unmarked connector on 
their junction box, or side of the Display unit), I found the data output 
on the green and black wire of the RJ-11.  Black was data ground, and 
green was RXD.  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.

SAVE A COMM PORT!  I can't believe the flack I get from people that want 
APRS to use COM3 and COM4 etc.  Why tie up whole COMM ports when an 89 
cent switch will allow other devices to share a single COMM port?  Since 
the U-II cable only uses ONE pin and GROUND, simply add it 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-II OPERATION:  There are two ways to combine a TNC and 
U-II for stand-alone remote operation.  One uses the new features in the 
PacComm TNC to periodically transmit a WX report, and the other permits 
APRS stations to interrogate the WX conditions remotely.  Here's how:

U-II and GPS capable TNC:  Program the TNC GPStext parameter to recognize
   the * or # character instead of the usual GPS formats.  Then set LOC
   to every 600 and GPS ON and the TNC will load the WX report into the
   TNC LText and transmit it once every 10 minutes.  Also SET ECHO off! 
   This is because the U-II uses a 10k resistor on the TXD line to bias
   the RXD line.  If the TNC is echoing the U-II data, then total garbage
   results!  (Thanks to KD4GOE for figuring that one out!).  Finally, you
   MUST put the unit's POSIT in the BText using the "_" WX symbol.

U-2000 and GPS capable TNC:  Do NOT program the GPS functions, but put the
   U-2000 into packet mode and put the TNC in "UIMODE" or whatever
   command sets the TNC to power up in  UNPROTO CONVERSE.  Once every
   5 minutes, the U-2000 will generate a packet.  You must set LFIGNORE to
   ON.  Since the Kantronics TNC's do not have LFIGNORE, you must set
   SENDPAC to $10 (linefeed) and set CR off!  If there are dozens of REMOTE
   U-2000's, hopefully their clocks are staggered enough that they wont
   all transmit at EXACTLY the same time.

OTHER NONO GPS CAPABLE TNCs: (obsolete, not worth the trouble, etc)
   1) Install the U-II and a TNC at the remote site.  Install a data switch
   so that U-II data is only input to the TNC when the TNC is connected by
   either wiring to the CONNECTED LED or to the DCD line if implemented
   2) Place the TNC location in the BText using the usual APRS fixed format
   with the WX (_) symbol:    !LLmm.xxN/LLLmm.xxW_Remote U-II WX station...
   3) If the TNC is also serving as a WIDE area APRS digi, place the word
   WIDE at the beginning of the comment field so that it shows up in green,
   and include a note that WX is available.  Set MYA WIDE.  Set your UNPROTO
   path to UNproto APRS via WIDE,WIDE... (assuming there are other WIDEs
   nearby)
   4) Set LFIgnore ON.  Set CHECK to 6 and AX25 off so that the WX connection
   will time out after 60 seconds.

At this point, any station connecting to the TNC will get the short ULTIMETER
15 character weather strings as long as they are connected.  The following
changes were made to APRS so that the connected station and all OTHER
monitoring stations could see the data.

   a) APRS looks for raw U-II data packets on the air, no matter what the
      TO callsign is.
   b) To let the station that connects to the U-II TNC also be able to see the
      data, he must first turn MCON ON so that he can monitor while connected,
      second, he must escape out of the APRS TALK mode so that APRS can process
      the data.  Use the alt-X key instead of ESC to return to APRS from the
      blue COMM-TNC screen.  Alt-X will leave your connection intact instead of
      forcing a Disconnect as it usually does.  This feature is not documented
      anywhere else, since it only is useful here for WX.
   c) As long as you are connected to the remote TNC, the U-II data will be
      transmitted about once every 5 seconds.

Since the remote site can also be a WIDE-RELAY digipeater, it should show the
WX circle symbol, but it will be GREEN to indicate it is also running with
the ALIASes of WIDE and RELAY.  Whenever U-II data is transmitted, APRS will
overwrite the digipeater position with the Ultimeter-II WX/posit report.  The
last WX heard will remain in the P-list and on the screen until the next
BText is transmitted by the DIGI TNC.

DATA LOGGING:  The POSITION FILTER normally causes APRS to NOT save duplicate
position reports that are within 80 yards of a previous report.  When this
filter is toggled OFF, it reduces this filter range to 20 yards AND enables
all WXstation logging.  In this mode, all WEATHER station reports are saved
in a track history file.  All over-the-air reports are only received once
every 10 minutes, but your own report will be saved at the rate set by the
Set-Pos-Rate command.

AUTOWX.EXE:  This is a program written by Les, N5KOA to also interface the U-II
to a TNC with a PC.  It allows direct connections for WX info, it does WX
beacons in APRS format, and allows continuous logging of WX data to a binary
file just like the U-II ULTIITSR program.  I have not used nor tried this
program.  Do not send disks, but about $5.00 to cover disk & postage.

    Les Blalock, N5KOA, 1711 Pagewood, Odessa, TX  79761
    (915) 332-7112 day, 332-1942 fax,   367-0408 eve

  The program is also available on the ARRL BBS at (201) 666-0578.

  THERE IS NO LONGER ROOM TO PROVIDE THIS PROGRAM NOR DOCUMENTATION AS
  PART OF APRS DISTRIBUTION.  AN OVERALL DESCRIPTION follows:

  AutoWX (Auto-Weather) is an IBM compatible packet program that accepts
  weather data from the Ultimeter II weather station and makes the data
  available on packet by direct connect requests and/or via automatic
  beacons (in APRS beacon format).  The program assumes you are using two
  serial ports (COM1 and COM2) and that the U-II is connected to one, the
  TNC to the other.  The program works fine on an XT with 256K RAM and a
  single floppy disk drive.  Weather data can be tracked on the AutoWx
  screen in three different formats:

  The WX.DAT file is an ASCII file that tracks the high and low temperatures
  and high wind speed for the day.  The U-II data is read continuously and
  logged to disk every 5 minutes.  If another packet station connects and
  sends "//wx", AutoWx will update and send the current weather data and
  Hi's and Lo's for the day.   The last ten stations that connected can be
  viewed by pressing the PgDn key.
        
  Comments and questions about AUTOWX can be directed to N5KOA at
  N5RKN.#WTX (Odessa, TX).  Please drop him a line if you try the program.


FINAL NOTES:  Since the WXstation option is always updating your outgoing
position report, this makes it impossible for a WX station to report a beam
heading during a Direction Finding evolution.  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.

$$$  The ULTIMETER-II is available from PEET Bros 1-800-USA-PEET (872-7338)
     for $179 plus $20 for their Serial interface cable and $60 for the
     optional rain guage (self emptying, reads in 0.1 inches) plus shipping
     of $8.25.  (For APRS, you don't need their $40 software but it is a good
     package for doing the usual home WX logging and analysis)  See adds in
     QST, CQ, Popular Mechanics, etc... (these were 1993 prices)

     The ULTIMETER-2000 is also available for about $200 MORE and includes
     RAIN, Humidity, and Barometric pressure.

