Ham Radio 2000/Ham Radio 2000.iso/ham2000/packet/aprs75c/wx.txt

Text File | 1996-04-02 | 20KB | 340 lines

WX.txt 7.5a    USING APRS IN WEATHER AND SKYWARN APPLICATIONS

New in 7.5a:   Added WX-DISP-wx and WX-SHOW-temp commands which tell your
               APRS to display WX stations on the map with current WX condx
               instead of callsigns.

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 - The JUST-WX command will cause only WX stations to be
     shown on the map or P-List.  New in version 75a, this feature
     toggles on or off.  The APRS NEXT command cycles through each WX
     station in turn and displays its weather conditions 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 it will be transmitted to all other stations.  If
     the object is given a course and speed of advance, then it will be
     automatically dead-reckoned on all screens until the next update.
     Any station can update the location of an object.  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 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.

     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 an old PC, this system can automatically inject WX storms
     into APRS nets!  It needs more work on additional parsing.

 ON-MAP-WX DISPLAY - New in version 7.5a, you may select to have the WX
     conditions displayed by each WX station instead of the callsign.
     There are two formats.  One is activated by the WX-DISP-wx command
     shows the TIME, Barometric Pressure, sustained wind and peak wind,
     The other is activated by the WX-SHOW-TEMPS command.  It substitutes
     Temperature for the TIME:

     1420z976/36/45       Time,1420. Pressure 976. Wind 36 gusts 45
     076'F876/36/45       Temperature of 76 degrees Faranheit

 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.


    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 inproperly 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.   To
demonstrate the NWS capability, center your map on FLorida at the 128
mile range enter the WX-GET_NWS_SITES command.  Once all the NWS stations
appear on the map, then enter the WX-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 wind speed in KPH and temperature in
Celsius 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 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.

ULTIMETER-II INTERFACE:  With the optional $9 WX registration, APRS
inserts the ULTIMETER-II conditions in your position report automatically
for unattended weather reporting.  Ultimeter data that begins with a *
output wind in MPH and those with a # in KPH.  APRS detects the
difference and does the conversion.  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 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 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 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.

SAVE A COMM PORT!  You can use a simple 89 cent switch to allow other
devices to share a single COMM port with the Ultimeter?  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 build a remote
WX reporting station.  With the ULTIMETER-II, you use the new GPS feature
in most TNCs to do the timing for periodically transmiting a WX report.
With the new U-2000, you simply put the U-2000 into packet mode and
put the TNC into CONVERSE mode.  Here's how:

For the U-II:    Program the TNC GPStext parameter to recognize the * or
# character instead of the usual GPS formats.  Then set the timing for
each transmission to be about once every 5 minutes.  Be sure to 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!  (KD4GOE figured that one out!).

U-2000 and RECENT TNC:  Do NOT program the GPS functions, but put the
U-2000 into packet mode and put the TNC in "UIMODE", or PMode-CONV 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.

WX POSITION:  In both cases, you must put the unit's POSIT in the BText
using the "_" WX symbol.  What is transmitted by the TNC then is a BText
WX posit with no WX data, and 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 10 minutes.  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.  This will not happen until a POSIT beacon comes in AFTER
a WX report.

DATA LOGGING:  The POSITION FILTER normally causes APRS to NOT save
duplicate position reports that are within 80 yards of a previous report.
If you toggle this filter 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 to:

    Les Blalock, N5KOA, 1711 Pagewood, Odessa, TX  79761
    [phone] day, 332-1942 fax,   367-0408 eve
    Packet: N5KOA @ N5RKN.#WTX (Odessa, TX).

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, 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 ads 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.