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TUCoPS :: Radio :: weathsat.txt

How to receive weather pictures from NOAA satellites






        HOW TO RECEIVE APT PICTURES FROM THE NOAA SATELLITES
        ----------------------------------------------------

So  you  have  decided you want to receive the NOAA and Russian METEOR
orbiters  and  you  have  a  radio  that  receives  137.500  MHz and a
computer.  So  now what do you do? I hope this short dissertation will
steer you in the correct direction.

To  display a picture from the orbiting birds you need several things.
First  you  need  to  'acquire' the satellite. This means you need the
program to calculate its position at any time and determine if you can
hear  the  signals from the 'bird'. The best place to get this program
is  probably AMSAT-NA an organization dedicated to AMateur SATellites.
They have several very good tracking programs for the IBM and also for
Commodore  and  Apple as well. After you have acquired the program and
have it running on your computer, you then need the Keplerian Elements
for  the  NOAA  satellites.  These  elements  as well as some tracking
programs  are  available from the CELESTIAL RCP/M, run by TS Kelso, at
513-427-0674 (Fairborn,OH) and from the Weather Fax and Remote Imaging
DATALINK BBS run by Dr. Jeff Wallach, N5ITU as bulletins for some 100+
sets of satellite  data.   Another bulletin also tells you to what the
printed  numbers  correspond  so  you can enter them into the computer
program.  Use  the  newest  elements  you  can  find  as  the orbiting
satellites are subject to forces which change their orbits. If you use
Keplerian Elements more than 3 or 4 weeks old, your chances of hearing
the bird are reduced. 

Once you are tracking the birds you should hear them on your receiver.
They  will  be on 137.62(NOAA-9/11), 137.500(NOAA-10), and on 137.850,
137.400, and 137.300 for Soviet Meteorlogical Satellites / METEOR. Now
comes  the  first  thing  different about NOAA orbiters. The frequency
deviation  of  the  FM  transmission  is about +/-18-20 kHz. This is 4
times  the  normal deviation of a police call and 1/3 the deviation of
the  FM  broadcast  band  FM  signal. If you receive the signal on the
regular  communications  width  of  the scanner the light areas of the
picture  will  be  noisy  and  the signal will sound distorted and the
picture  will  basically  be  useless.  If  you  use  the FM broadcast
bandwidth  (assuming  your  scanner  will let you), the signal will be
weak and there may be too much background noise to see the picture. 

So  what  now ?   Well there  are two  ways to fix the problem, find a
receiver  with  the  proper I.F. bandwidth filter of 50 kHz, or modify
the  I.F.  of  your scanner to about 50-80 kHz. The simplest mod which
has  been  found to be workable is to remove the narrow communications
I.F.  filter  and  replace it with a 0.01 uFd capacitor. This provides
for  good  Wefax  pictures  from  GOES  and  pretty  fair NOAA orbiter
pictures.  It  can of course result in retuning the radio, voiding the
warranty and making the squelch not work properly.

The  other  characteristic of the NOAA satellite transmissions is THEY
ARE  WEAK.  To  get  good  pictures  over a large area we have found a
pre-amplifier  to  be  essential. A GaAs-FET type can be obtained from
various  sources at a reasonable price but still about 50-100 dollars.
You  can  also build one for about 25 dollars from plans for a pre-amp
for the 2-meter amateur band and tune it to 137.5 easily.

Lastly,  but  importantly,  the antenna can be of an omni directional,
uniform pattern type such as a turnstile antenna similar to those used
in  the  FM  broadcast reception business but of course tuned to 137.5
MHz. Mount the pre-amp at the antenna if possible. Crooked coathangers
on  broomsticks  have  been  known to work, and it is not difficult to
build the antenna. Of course 2-meter beams with Az/El tracking will do
the job well.






Now that you have a nice audio signal from the satellite, what happens
next? The audio tone of 2400 HZ which is the carrier tone that is used
to  carry  the  picture  information (video), must be detected and the
video  data converted from analog to digital and then displayed on the
computer monitor by the software. The hardware and software to do this
is  available  from  several  sources  with more coming along. Several
stand-alone  boxes  are  also  available  that  produce  some  form of
computer  output either in printed form or on the display. In addition
the  people  on the DATALINK BBS may also have some data to share with
you regarding this equipment.

One  of  the  best  sources  for  information is the WEATHER SATELLITE
HANDBOOK  by Dr. Ralph Taggart. The 4th edition will be available from
the  ARRL later this year.  A must is THE JOURNAL OF THE ENVIRONMENTAL
SALELLITE   AMATEUR  USERS'  GROUP  -  JESAUG  -  which  is  published
quarterly.  It  is available for $30.00 per year from the editor, Jeff
Wallach,  PO Box 117088 Carrollton, TX. 75011-7088. Back issues of the
JESAUG are also available. 

One good place to start is with the Elmer Schweittek MULTIFAX software
which  runs  on  the  IBM  PC.  A  hardware  kit is available from A&A
Engineering  which  includes  the  video  dectector  circuit  and  A/D
converter.  Input to the PC is via the game port. If you want to build
your  own,  complete documentation to build an interface circuit on an
IBM  PC  prototyping  board is available from H. Paul Shuch, N6TX, for
$6.00 - FAXBOARD is also described in QEX, Sep `88. 

The  units  available  from Jim MacLean, Ralph Taggart, and Jerry Dahl
listed  under Sources are all well worth investigating if you are just
getting  started.  DATALINK will have available by early summer an APT
interface card for the IBM PC that can be built for less than $100. 




                     'Typical' APT Receiving Station
                     -------------------------------


        [1]   ANTENNA
                 -
        [2]   PRE-AMP
                 -
                 -
                 -
                 -                          [ STAND ALONE UNITS ]
                 -
        [3]   RECEIVER  ----------------->  FAX MACHINE  ---> PAPER
                 -                          WRASSE UNIT  ---> MONITOR
                 -                          YU3UMV UNIT  ---> MONITOR
                 - - - - VCR
                 -
                 -
                 -
        [4] - VIDEO DETECTOR   -
            -                  -
            -                  -
        [5] - ANALOG/DIGITAL   -
            -                  -
            -                  -            [ SCAN CONVERTERS ]
            -                  -
        [6] - INTERFACE TO PC  - <=======>  ROBOT 1200
            -                  -            TAGGART'S 1700 
            -                  -            IMAGEWISE
            -                  -
        [7] -    SOFTWARE      -            ** SECOND DISPLAY **
            -                  -               for weather images
            -                  -
            -                  -
        [8] - GRAPHICS ADAPTOR -
                 -
                 -
                 -
                 -
        [9]   PC DISPLAY / MONITOR

                 Display weather images
                 (or commands for SCAN CONVERTERS)


       [10]   PC PRINTER / DOT MATRIX / LASER



       NOTES:
       ------

              [4] VIDEO DETECTOR, [5] ANALOG/DIGITAL CONVERTER, and
              [6] INTERFACE TO PC may be in seperate hardware units
              or all on one circuit board.





Sources:
----------------------------------------------------------------------

NOAA Data / Keplerian Elements:

DATALINK RBBS, N5ITU, Dr. Jeff Wallach, 214-394-7438,
 DALLAS REMOTE IMAGING GROUP ELECTRONIC BULLETIN BOARD
 UPDATES ON NOAA BULLETINS, SATELLITE LAUNCHES, FREQUENCIES
 DISPLAY PICTURES FROM NOAA SATELLITES ON YOUR OWN P.C.

CELESTIAL RCP/M, TS Kelso, 513-427-0674, NASA Prediction Bulletins         
 are online and updated several times weekly                               

Satellite Tracking Software:

AMSAT-NA,  PO  Box  27, Washington, DC 20044, Software Exchange,
 phone 301-589-6062 (voice), N4HY - QUIKTRAK, W0SL - ORBITS II,III,IV,
 and InstantTrack by Franklin Antonio.                                    |
Roy D. Welch, W0SL, 908 Dutch Mill Drive, Manchester, MO 63011,
 phone 314-391-1127, ORBITS II-CGA, ORBITS III-EGA, ORBITS IV-VGA          
DATALINK BBS, download SATTRAKx.ARC, SEESATxx.ARC, TRACKSAT.xxx and others|
CELESTIAL RCP/M, TS Kelso, 513-427-0674, SATTRAKx.ARC or SEESATxx.ARC      
Astronomical Data Service, Rodger Mansfield, 3922 Leisure Lane,
 Colorado Springs, CO 80917-SPACE BIRDS program and Newsletter, $40.

Receivers:

Vanguard Labs, 196-23 Jamaica, Hollis, NY 11423,
 phone 718-468-2720, BBS Dataline 718-740-3911                            |
Hamtroincs, Inc.,65-D Moul Road, Hilton, NY 14468-9535
 phone 716-392-9430
DARTCOMM, Mr. N. Hearn, DARTCOMM Ferndale, Postbridge, Yelverton,          
 Devon PL20 6SY, Great Britain, UK, phone 011 44 0822 88253                
Quorum Communications, PO Box 277, Grapevine, TX 76051,                   |
 phone 817-488-4861, BBS Dataline 817-464-7284                            |

Crystals:

JAN  Crystals,  2400  Crystal  Dr,  Fort  Myers,  FL 33906-6017,
 phone 1-800-237-3063 or 813-936-2397

Pre-Amps:   

Quorum Communications, PO Box 277, Grapevine,TX 76051                      |
Spectrum   International,Inc.,  Box  1084,  Concord  MA  01742,
 phone 617-263-2145
Vanguard Labs, Hamtronics and GLB for Helical RF Filters for intermod
Ehrler-DuBois Very High Performance LNA for 1500-1750 Mhz, contact         
Greg Ehrler or John DuBois via DATALINK                                    

Antennas:

ARRL Handbook, 1986, turnstile over ground antenna.
ARRL Satellite Experimenter's Handbook by Martin Davidoff, K2UBC
Modern Electronics, September 1988, Hank Brandli article, page 82,
 Receiving Satellite Weather Photos

Hardware Interface to PC:

A&A  Engineering,  2521  W. La Palma, Unit K, Anaheim, CA 92801,
 phone 714-952-2114 - both AM dectector and A/D converter, input to PC
 via game port (4-bits) or parallel I/O Interface (8-bits) - kit is
 $50. - assembled and tested unit is $70.
Microcomm,  H. Paul Shuch, N6TX, 14908 Sandy Lane, San Jose, CA 95124,
 phone 408-377-6137 - FAXBOARD - A Weather Facsimile Display Board for
 the  IBM  PC  -  Complete  documentation  to build your own interface
 circuit  on  an  IBM  PC  prototyping  board - video and an 8-bit A/D
 interface - $6.00, also in QEX, Sep '88.

Video Detectors:

RTM  Circuit  Boards,  205  Elm  St.,Van  Horne, IA  52346-0400,
 video detector  (the 'Wilson Board')  see QST Magazine, Jan '86 and
 Vince Coppola's  article in Oct 1988  73 Magazine
QST Magazine, August 1985, Grant Zehr article, page 27, video detector
 circuit

A/D Converter & Parallel I/O Interfaces for the IBM PC:

MetraByte,  440  Myles Standish Blvd., Taunton, MA 02780, Model PIO-12
 board for the IBM PC, phone 617-880-3000
John  Bell  Engineering, Inc, 400 Oxford Way, Beimont, CA 94002,
 phone 415-592-8411





Sources:
----------------------------------------------------------------------

Display Software and Hardware - 'Amateur':

Multifax, Elmer Schwittek, 2347 Coach House Lane,Naples, FL 33942,
 phone 813-434-2268 - Multifax 4.x for VGA, 3.x for EGA on the IBM-PC     |
Clay Abrams Software, 1758 Comstock Lane, San Jose, CA 95124, software
 for the ROBOT 1200 - see QST Magazine, Jan '86
Ralph  Taggart,  602  S. Jefferson, Mason, MI 48854, Weather Satellite    |
 Handbook  Scan  Converter - New Model 1700 APT Scan Converter for the    |
 the  IBM PC. Order Handbook from the ARRL, Scan Converter from Metsat    |
 Products,  1257  Glen  Meadows  Ln,  East  Lansing  MI,  48823, phone    |
 517-332-7665.   Also   see   73   Magazine,  Nov  '84  and  Dec  '84,
 WSH/Handbook,  and  WEATHERSAT  columns  in 73 Magazine from 1987 and
 1988. 
ImageWise  Display/Receiver,  Circuit  Cellar Inc. - Micromint Inc., 4
 Park  Street,  Vernon,  CT 06066, phone 203-875-2751 - BYTE Magazine,
 May,  Jun,  Jul,  Aug 1987. JESAUG 88-2 and Oct 1988 73 Magazine have
 information  on  how  to  build  the video and A/D interface. Ver 2.0
 software  supports  VGA  graphics and 640 samples per line at 64 gray
 levels.  With  VGA  the  ImageWise  Display unit is not required. The
 software  is  available for $29.95 from Vince Coppola, N1VC, 6 Bobbin
 Road, Terryville, CT 06786 
ASAT:  An Apple-based Satellite Imaging System by Grant Zehr, WA9TFB -
 QEX  Magazine,  March  '88  -  has  complete  information to build an
 excellent  unit  using  the  APPLE  with a Redshift Ltd graphics card
 giving 256 * 256 pixels at a full 256 levels of gray. 

AMIGA Imaging Software - Dallas Remote Imaging Group                       
                         PO Box 117088                                     
                         Carrollton, TX 75011-7088                         
                         Voice 214 394 7325                                
 Uses standard Amiga hardware - no special display                         
 Powerful NASA digital enhancement curves built-in                         
 Digital image processing capabilities                                     
 Uses A&A Engineering $49 demodulator                                      
 Image saved for use by other graphics programs                            
 Full histogram analysis                                                   
 Full 8 bit data is stored on diskette or hard disk                        
 Unattended operation                                                      
 Can be setup in 30 minutes                                                
 Call for special pricing                                                  

IBM-PC  Interface  Card  and Software - Jim MacLean and Paul Atkinson,    |
 2112 Parsons Avenue, Melbourne, FL 32901, 407-727-3646 - plug in card    |
 for   IBM  XT  or  AT,  9600  samples/second  at  8  bits,  automatic    |
 synchroniztion  for  NOAA,  METEOR  and WEFAX, data saved realtime to    |
 hard disk, supports CGA, EGA, and VGA, $300 for hardware and software    |
A Weather-Facsimile Package for the IBM PC  by Jerry Dahl in April and    |
 May  '90  QST describes how to construct a complete FAX system. Notes    |
 at  the  end  of  artilce  contain  an excellent list of hardware and    |
 software sources                                                         |

Complete Systems - Hardware and Software:

YU3UMV  Digital  Storage  and  Scan  Converter  for  Weather Satellite
 Images,  described  in  VHF  Communications Magazine, Winter 4/82 and
 Spring  1/83  -  Modifications  are described in the Satellite Users'
 Group  Journal - JESAUG - available from Jeff Wallach. Back issues of
 VHF Communicatons and the YU3UMV printed circuit boards are available
 from  Fred Sharp, TimeKit, P.O. Box 22277, Cleveland, OH 44122, phone
 216-464-3820.
Loren  Johnson,  P.O.  Box  219,  Cleveland,  MN 56017, system for the
 IBM-PC  -  $750,  phone  507-931-4849
WEATHERTRAC[tm] IBM-PC Based Satellite Image Acquisition and Animation     
 System  -  $1885  for  EGA - $3495 for VGA, Fred Bartlett, Softworks,     
 Inc,  Allentown,  PA, phone 215-395-4441 or George Isleib, Lehighton,
 PA, phone 717-386-4032
Quorum Communications, PO Box 277, Grapevine, TX 76051,                   |
 phone   817-488-4861,   BBS Dataline  817-464-7284,  offers  a  fully    |  
 integrated  system  for  the  IBM  PC  including GOES down converter,    |
 GOES/APT  receiver,  Wefax  PC  Adapter  and software. A demo disk is    |
 available on request or via the Quorum BBS.                              |

Satellite Meteorology:

Satellite  Imagery  Interpretation  for  Forcasters  -  a 3 volume set     
 published  in  1985  for NOAA now available from the National Weather     
 Association,  4400  Stamp  Road,  Room  404,  Temple Hills, MD 20748,     
 301-899-3784,  $32  for  members, $45 for non-members ( Membership is     
 $20. )                                                                    



Bibliography - Online DATALINK Bulletins:   (214 394 7438 -- BBS)

NASA Satellite Prediction Bulletins, NASA-PB.xxx
How to use NASA 2-Line Keplerian Elements
AMSAT Bulletins and Weekly Notes / Orbital Elements
NOAA APT NOTES
NOAA User Bibliography
Summary of Soviet Meteorological Satellites by Grant Zehr
How to Build a Weather Satellite Groundstation (This Primer)
Wrasse Dedicated System Review
GOES VAS Imaging System for the IBM PC, John DuBois W1HDX                  
LNA for WEFAX-VAS-HRPT-GPS, John Dubois and Greg Ehrler                    
GOES I-M Converence Summary                                                
Ralph Taggart's New  APT Scan Converter and Book                          |
Dartcom 137-138 Synthesized Receiver Packaging, John DuBois               |
Amateur Radio News from Newsline, Bill Pasternack                         |
How to VISUALLY OBSERVE the Space Shuttle, Ted Molczan                    |
AMSAT InstantTrack V1.00 program description, Franklin Antonio            |

 


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