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HOW TO RECEIVE APT PICTURES FROM THE NOAA SATELLITES
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HOW TO RECEIVE APT PICTURES FROM THE NOAA SATELLITES
----------------------------------------------------
Courtesy Dallas Remote Imaging Group
Datalink RBBS =============> 214-394-7438
Dedicated to satellite tracking, decoding of NOAA/Soviet
meteorological satellite telemetry, and Digital Image
Processing of satellite pictures.
Jeff Wallach, N5ITU, Chairman
John Williams, Co-Chairman
Tom Kelso, Air Force/NASA liason
Jim Blocker, KF5IW, Director Software Development
Jose Sancho WB5YFU, Director of Engineering
All aspects of Amateur Radio covered on Datalink RBBS
(IF YOU COPY THIS BULLETIN FOR OTHER SYSTEMS, PLEASE BE KIND ENOUGH
TO LEAVE THIS BANNER AS DUE CREDIT TO THE HARD-WORKING FOLKS WHO
DEVELOPED AND CONTINUALLY UPDATE THIS INFORMATIVE 'HOW-TO'BULLETIN)
December 15, 1987
(rev 6)
Tom Gentry, K5VOU, has been kind enough to help prepare the following:
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
512-892-4180 (Austin, TX) and from the Weather Fax and Remote Imaging
DATALINK BBS run by Dr. Jeff Wallach, N5ITU as bulletins for some 50 +
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), 137.500 (NOAA-10), 137.850 (Meteor
2-14,2-15) and 137.4 (Meteor 2-16). 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 needs to 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 with the
pre-amps mounted on the broomstick, so it is not difficult to build
the antenna.
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 available from Dr. Ralph Taggart of Michigan State University
at 602 S. Jefferson, Mason, MI 48854 for $12.50. Taggart also writes a
monthly WEATHERSAT column which appears in '73 Magazine. A must is THE
JOURNAL OF THE ENVIRONMENTAL SALELLITE AMATEUR USERS' GROUP - JESAUG -
which is published quarterly. It is available for $12.00 per year from
the editor, Greg Mengell, 2685 Ellenbrook Drive, Rancho Cordova, CA
95670. Back issues of the 'Journal' are also available.
At the present the simplest software for the IBM is the Elmer
Schweittek MULTIFAX 2.0 software. 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
$5.00 - FAXBOARD.
The WEPIX(tm) software and hardware should be available from Encomm
before Christmas time this year and it will produce pictures of 1200
lines 800 samples of each line displayed in 200 x 200 pixels in 16
shades of gray or 16 colors using an IBM PC with 640kB, EGA card and
at least one 360k disk.
'Typical' APT Receiving Station
-------------------------------
[1] ANTENNA
-
[2] PRE-AMP
-
-
-
- [ STAND ALONE UNITS ]
-
[3] RECEIVER -----------------> FAX MACHINE ---> PAPER
- WRASSE UNIT ---> MONITOR
- YU3UMV UNIT ---> MONITOR
-
-
-
[4] - VIDEO DETECTOR -
- -
- -
[5] - ANALOG/DIGITAL -
- -
- - [ SCAN CONVERTERS ]
- -
[6] - INTERFACE TO PC - <=======> ROBOT 1200
- - TAGGARTS'S WSH
- - 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 SATS ON YOUR OWN P.C.
CELESTIAL RCP/M, TS KELSO, 512-892-4180
Tracking Software:
AMSAT-NA, PO Box 27, Washington, DC 20044, Software Exchange,
phone 301-589-6062 (voice)
DATALINK BBS, download SATTRAK0.ARC or ORBIT1-C.ARC
CELESTIAL RCP/M, TS KELSO, 512-892-4180, SATTRAK0.ARC and others
Receivers:
Vanguard Labs, 196-23 Jamaica, Hollis, NY 11423,
phone 718-468-2720
Hamtroincs, Inc.,65-D Moul Road, Hilton, NY 14468-9535
phone 716-392-9430
Crystals:
JAN Crystals, 2400 Crystal Dr, Fort Myers, FL 33906-6017,
phone 1-800-237-3063 or 813-936-2397
Pre-Amps:
THL/Encomm, Inc, 1506 Capital Ave, Plano, TX 75074, phone 214-423-0024
Spectrum International,Inc., Box 1084, Concord MA 01742,
phone 617-263-2145
Vanguard Labs, Hamtronics and GLB for Helical RF Filters for intermod
Antennas:
ARRL Handbook, 1986, turnstile over ground antenna.
ARRL Satellite Experimenter's Handbook by Martin Davidoff, K2UBC
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 - $5.00
Video Detectors:
RTM Circuit Boards, 205 Elm St.,Van Horne, IA 52346-0400,
video detector only (the 'Wilson Board') see QST Magazine, Jan '86
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
Display Software:
Encomm, Inc. 1506 Capital, Plano, TX 75074, WEPIX(tm) system,
phone 214-423-0024
Elmer Schwittek, New Address: 2347 Coach House Lane, Naples, FL 33942,
Multifax 2.0, phone 813-434-2268
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 - for the Radio Shack CoCo3 - see 73 Magazine,
Nov '84 and Dec '84 and Handbook
Marta Systems, 209 W. Santa Paula St, Santa Paula, CA 93060,
phone 805-933-1270, 'Live From Space' for the AMIGA PC - $500.
ImageWise Display/Receiver, Circuit Cellar Inc. - Micromint Inc.,
4 Park Street, Vernon, CT 06066, phone 203-871-6170 - BYTE Magazine,
May, Jun, Jul, Aug 1987. DATALINK can provide information on software
and video interface
Complete Systems - Hardware and Software:
Loren Johnson, P.O. Box 219, Cleveland, MN 56017, system for the
IBM-PC - $750, phone 507-931-4849
Greg Mengell, 2685 Ellenbrook Drive, Rancho Cordova, CA 95670,
APT Associates, phone 916-364-1572, Wraase System and FAX recorders
(Ask for DEPT. J. == Specify referral by Dallas Remote Imaging Group)
YU3UMV Digital Storage and Scan Converter for Weather Satellite
Images, described in VHF Communications Magazine, Winter 4/82 and
Spring 1/83 - printed circuit baords and modifications described in
the Satellite Users' Group Journal - JESAUG - are also available from
Greg Mengell
Bibliography:
NOAA Satellite Predictions, see DATALINK Bulletins
NOAA APT NOTES, see DATALINK Bulletin
NOAA Bibliography, see DATALINK Bulletin
Summary of Soviet Meteorological Satellites, see DATALINK Bulletin
Wrasse Dedicated System, see DATALINK Bulletin
MULTIFAX 2.0, see review on DATALINK BBS - download MULTIFAX.DAT
Review DATALINK RBBS bulletins for more information.
DALLAS REMOTE IMAGING GROUP - DRIG ==============> 214-394-7438
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