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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