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NOTE: THIS POSTING IS IN RESPONSE TO A QUESTION POSTED ON THE WX-TALK LIST)

                          WWIN TECHNICAL INFORMATION

   Last updated: Jan 16, 1996 -- KRK

   The Wireless Weather Information Network (WWIN) system is a method for
   disseminating digital weather information using inexpensive radio
   broadcast and personal computer (PC) technologies. The NWS transmits
   selected text, graphics, and imagery products as an audio signal on a
   dedicated VHF radio frequency. This information can be received, by
   anyone within the 30-60 mile broadcast area, using an inexpensive
   radio receiver, a demodulator, and a personal computer. WWIN software
   on the PC, running under Windows, receives the signal through a serial
   port, stores the received weather products onto disk, and
   simultaneously allows you to display this information.

   Products include: current weather forecasts and warnings for every
   state, temperature charts for many worldwide cities, national weather
   graphics, satellite photos, and much more. Radio broadcast is just one
   method for distributing the WWIN audio signal and data; other
   potential methods are: cable TV, satellite, SCS, SAP, etc.

   The WWIN system has been operational since May 1994. At present, it is
   still under evaluation, being demonstrated in the Washington DC
   metropolitan area as a VHF broadcast on 163.350 MHz from Silver
   Spring, MD. The signal and data stream are also available in various
   other locales; see the list of Broadcast Areas. NOTE: This is an
   experimental system which could be interrupted or discontinued at any
   time. We hope to expand to national coverage, but this is not at all
   guaranteed. The future will depend upon NWS policy decisions and
   funding, and public interest in accessible data.

   See the list of Commercial Vendors for WWIN software and hardware. We
   provide free public-domain software for receiving WWIN data and a
   schematic for the necessary demodulator. This is provided as-is. We do
   not provide support, other than the enclosed documentation, for
   software or hardware problems. Please understand that we are not
   staffed to provide such support, nor do we want to compete with
   commercial suppliers of enhanced WWIN software or hardware kits.

   Kevin Kay
   NWS WWIN Project
   1325 E-W Hwy, W/OSO12
   Silver Spring, MD 20910
   (301) 713-0191 x172
   kkay@nws.noaa.gov
     _________________________________________________________________


  WWIN Installation Notes

   What Do I Need?

     a)   a location within 30-60 miles of the transmitter site,
          e.g. Silver Spring, MD; Tulsa, OK; Norman, OK; etc.
     b)   a PC capable of running Microsoft Windows, generally a
          386DX40 or better, with 4MB or more RAM; 10+ MB of disk
          space available on C:; SVGA 640x480, 256 color driver;
          one COM serial port; a mouse; a 3=" diskette drive.
     c)   MS-DOS 5.0 or later.
     d)   MS Windows 3.1 or later; we have not tested Windows NT.
     e)   WWIN receive/display software (public domain or vendor).
     f)   a demodulator (see enclosed example schematic) which can
          be bought as a kit, or assembled (see vendors).
     g)   a radio receiver or scanner, tuneable to the broadcast
          VHF frequency, e.g. 163.350 MHz in the Washington area
          (such as the Uniden Bearcat BC55XLT, but anything works)
     h)   a decent antenna, depending upon range, line-of-sight,
          and shielding (see Chapter 5.2 in the User's Handbook).

   How Do I Load the Software?

     a)   For commercial vendor software, see their instructions.
     b)   For our WWIN software, use the automated Install procedure
          to decompress and copy the necessary programs and data files.

   How Do I Hookup the Hardware?

     Connect the audio output of your receiver to your demodulator
     input; connect the demodulator RS-232 output to your COM port.

   How Do I Get It Working?

     a)   For our software, see Chapters 2 and 5 in the User's Handbook.
     b)   You will initially need to experiment with placement and
          orientation of your antenna.  Remember: you can listen to
          the audio modulation on your radio corresponding to each
          block of data, which are sent every 10-15 seconds.
     c)   You do not need our NOAARX Receive software task running
          continuously 24 hours a day.  You may miss some products
          but local products are retransmitted periodically (every
          30 minutes) during the day to keep you current.
     d)   You do not need the WWIN Display software task running
          except when you want to view the weather products.
     e)   You do not need the UNPACKER software task running at all
          if you have no need for the national products & pictures.
     f)   You do not need the SPOOLER software task running at all
          if you are not going to print out any of the products.

   If I Have Problems?

     a)   See Chapter 5 on Troubleshooting, in the User's Handbook.
     b)   Call your vendor for support.
     c)   Remember: we may be "off the air" at any time.


     _________________________________________________________________


  WWIN Broadcast Areas

1)   The WWIN data is broadcast in the Washington DC metropolitan
     area by VHF radio from Silver Spring, MD on 163.350 MHz, and
     is receivable (once demodulated) as normal async 1200,8,N,1.

2)   The WWIN data is broadcast in the Norman OK area by VHF radio
     on 169.025 MHz, and is receivable as normal async 1200,8,N,1.

3)   The WWIN data is broadcast in the Tulsa OK area by VHF radio
     on 165.0125 MHz, and is receivable as normal async 1200,8,N,1.

4)   The WWIN data is also being broadcast nationwide by PBS as an
     independent test. WWIN data is accessible on the PBS Telstar
     401 satellite: Transponder 5A, Channel 5, Secondary Audio
     Program (SAP), center frequency 11836.5 MHz (or 11.8365 GHz),
     vertically polarized. However, the signal presently is being
     multiplexed as part of their test and additional (Digicipher)
     equipment is thus required to receive the signal. Although
     this is not feasible for the general public, future tests may
     include lower-cost techniques permitting direct reception.

5)   Additional areas and further details as they become available.

   Disclaimer: Please remember that these broadcasts and the basic
   availability of our WWIN data stream are experimental at present, and
   could be withdrawn or discontinued at any time.
     _________________________________________________________________


  WWIN Products

   We are transmitting our standard data stream, as gathered from the
   AFOS network "Gateway", NESDIS, and other sources.

   Text :

These are the "readable text" products, of which there are dozens.
These include local and national watches and warnings,
such as the following products:
     EQR...    Earthquakes
     FAA...    Terminal Forecast
     FLW...    Flood Warnings
     FFW...    Flash Flood Warnings
     FFA...    Flash Flood Advisories
     HLS...    Local Hurricane Statements
     HUR...    National Hurricane Statement
     LFP...    Local Forecasts
     RVR...    River Stages
     SVR...    Severe Thunderstorm Warning
     SVS...    Severe Weather Statement
     NOW...    Short Term State Forecast
     SMW...    Special Marine
     SPS...    Special Weather Statements
     SFP...    State Forecast
     STP...    State Police Reports
     OTH...    State Weather Summary
     SWR...    State Weather Roundup
     ZFP...    State Zone Forecasts
     SAO...    Surface/Aviation Observations
     TOR...    Tornado
     SUM...    Weather Summaries
     WSW...    Winter Storm Watch

   as well as international temperature charts, and so on.

   Graphics :

     These are the GPH... products.  There are over 200 different subtypes,
     listed in file \WXDATA\RXTMP\GPHCTYPE.TXT, and include:
     clouds, dewpoint, fronts, humidity, isohyets, lightning, marine,
     precipation, pressure, radar, temperature, winds, and so on.


   Imagery :

     These are the SAT... products(generally "CC1" images), as received
     from GOES satellites via NESDIS.

   Other :

     These are the PIC... "interesting picture" products, which include
     stills of hurricanes and tornadoes, scanned charts of weather symbols
     and tutorials, Internet WWW examples,and so forth.

   What We Don't Transmit :

     Currently, we are not transmitting any current NEXRAD
     doppler radar products (e.g. from the Sterling Forecast Office).


     _________________________________________________________________


  WWIN Transmission Protocol

   The format of WWIN transmissions is public domain. The digital NWS
   data, whether ASCII text or binary, is sent as 1KB packets. Each file
   or product is sent as one or more packets, which are numbered 1..N
   within the given product. Because the data is packetized, a particular
   product can be gracefully interrupted by a high priority warning or
   alert product and then resume. Note: the broadcast is receive-only --
   hence the receiver has no means of notifying the transmitter of any
   block errors or of requesting retransmission of individual blocks.
   Instead each product is transmitted at least twice, to "fill in" any
   blocks received in error by some receiver.

   Each packet of data contains the following fields:

a)   6 bytes of ASCII 0 (NUL) to clear any receiver buffer.

b)   "/PF" followed by an 8-character filename, a period, and a 3-
     character filetype.

c)   "/PN" followed by the block number -- the number of this block
     (1..N) within this file.

d)   "/PT" followed by the total number of blocks (N) being sent
     for this file.

e)   "/CS" followed by a checksum number -- the sum of all bytes in
     the 1024-byte data portion of this packet, as a 16-bit
     decimal.

f)   "/FD" followed by the date/time stamp of this file -- in the
     format of: MM/DD/YY HH:MM:SS AM, without space padding.

g)   ASCII 32 (SP) fill -- to pad the total bytes in fields b..h to
     a full line of 80 bytes.

h)   ASCII 13 (CR) and ASCII 10 (LF) to enhance readability.

i)   the data, as a 1024-byte block; if the remaining data of the
     product is less than 1024 bytes, this block is NUL-filled so
     that each packet's data block is always 1024 bytes long.

j)   6 bytes of ASCII 0 (NUL) to clear any receiver buffer.

   An example of a typical packet header is:
   /PFZFPSFOCA.TXT/PN 3 /PT 5 /CS 63366 /FD2/10/95 5:24:26 PM

   The current VHF broadcasts are receivable as async 1200,8,N,1. The
   content of the NWS weather products (in the 1024-byte blocks) may be
   plain ASCII text or graphics or imagery. The products are not
   encrypted, but will often be compressed. Interpretation of the content
   of the products is up to the receiver's software. Details of the
   particular graphics, imagery, and compression formats are given below.

     _________________________________________________________________


  WWIN Transmission Protocol (continued)

   Text :

     AFOS text products are transmitted in English and are usually public
forecasts.  However, some products may contain a variety of terse
abbreviations or weather-specific acronyms, or may simply be "readable"
tables of computer-summarized data.  The first two lines of text of a
product are our NWS so-called "WMO" header, which includes: product
identifier, source site, state/zone destinations affected or targeted,
and expiration time.

   Graphics :

     AFOS graphics products are transmitted in our NWS so-called Universal
Transmission Format (UTF), a display-independent format.  This is
described in AFOS Handbook 5, Volume 6, Part 2, Appendix B, which is
available upon request (29 pages).  This format includes vectors,
characters, and gridded data, but not bitmaps or rasters, and was
originally designed to be closely compatible with our "GDM" displays.
Be alert to the "byte stuffing" described on page B-27.

   Imagery :

     Satellite images (SAT... products from GOES) are transmitted in a
display-specific format, namely as 4 consecutive bit-planes of VGA pels
(640x480x16 resolution). A product contains 6 sections:
     1)   first 36 bytes are ASCIZ text identifying the product;
     2)   next 38,400 bytes are plane 0;
     3)   next 38,400 bytes are plane 1;
     4)   next 38,400 bytes are plane 2;
     5)   next 38,400 bytes are plane 3;
     6)   final 988 (1024-36) bytes are pads, to fill up block 151.

The planes can be directly copied to successive VGA planes 0,1,2,3.

   Other :

     Pictures (PIC... products) are transmitted in standard formats as
indicated by the filetype/extension.  Currently, .GIF is used, so any
shareware program can display these "interesting pictures".

   Compression :

     Local data and watches/warnings/adviseries are transmitted as clear
text and not compressed.  Other national data products, such as all SAOs
for a given hour, are first packed into one "file" and then compressed
and transmitted.  The WWIN "UNPACKER" software task will decompress these
CMP or .ZAP or .NWS "files" upon receipt, and then unpack the constituent
data products as if received normally.

   The compression/decompression software used is the standard PKWARE
   Data Compression Library. Note: their "generic compression format
   used" is "not specific to their PKZIP format" --- which means you
   cannot decompress these files using the shareware PKUNZIP program. We
   supply PKWARE's Windows public-domain version, as MRCPAKIT.DLL and
   PDUNPACK.EXE; versions for other platforms may be available from
   PKWARE.
     _________________________________________________________________


  Commercial Vendors of WWIN Products

1)   Maryland Radio Center, Inc.
     8576 Laureldale Drive
     Laurel, MD  20724
     (301) 725-1212
     (800) 447-7489
     BBS with demo software (301) 725-8307

     a)   MRC demodulator kit, unassembled                         $29.95
     b)   MRC demodulator, assembled and tested                    $69.95
     c)   MRC Weathernode software                                 $49.95
     d)   MRC WeatherNode software plus the demodulator kit        $69.95
     e)   MRC WeatherNode software plus the assembled demodulator  $99.95

     $5 shipping, + 5% sales tax for MD addresses.
     Call for their latest prices and special discounts.

2)   SkyWalker Data Systems, Inc.
     7303 West 35th Str.
     Tulsa, OK  74107
     (918) 445-1488

     a)   MRC Weathernode software plus the assembled demodulator  $99.95


     _________________________________________________________________


  WWIN Schematic

MRC DM-201B Demodulator Schematic

   This is one example of a demodulator to receive the WWIN audio signal
   and convert to RS-232 serial "ASCII" data bytes, courtesy of Maryland
   Radio Center. There are many similar public-domain demodulator circuit
   designs using various ICs, such as the XR-2211 chip or TCM3105JL chip
   to demodulate plus a MAX-232ACPE chip or equivalent to convert to
   RS-232.
   As posted on the Milwaukee Area Skywarn Association, Inc. Bulletin
Board System.
   MASA On-Line B.B.S
   (414)229-6664
   Internet:  omnifest.uwm.edu
   Telenet:   128.89.70.58
   @ login:   visitor (lowercase)
   @ menus:   go skywarn
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