Precision Software Applications Silver Collection 3

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============================================================================ DALLAS REMOTE IMAGING GROUP BBS =====>> 214-394-7438 FAX 214-492-7747 VOICE 214-394-7325 DEDICATED TO SATELLITE IMAGERY, SATELLITE TRACKING, NASA, DIGITAL SIGNAL PROCESSING, IMAGE PROCESSING, AMATEUR RADIO, AND ELECTRONIC INTELLIGENCE PCBoard SUPPORTS 6 Lines (USR Dual Standard V.32bis V.42 24 hrs. Daily) E-MAIL FOR Weather Satellite Report and InterNet UUCP News Groups ON-LINE HAMCALL APPLICATION - LOOKUP HAM CALLSIGNS On-Line SATTRAK Satellite Tracking Routines On-Line SHOP Satellite Resource Center - On-line Ordering On-Line BALLTRAK Balloon Launch and Tracking Program THOUSANDS OF IMAGE FILES OF SATELLITE IMAGE AND NASA VOYAGER IMAGES SATELLITE TRACKING PROGRAMS, IMAGE PROCESSING, DSP, ATV, SSTV, FAX ============================================================================ Documentation for SBDSP - SoundBlaster APT Demodulation Program ---------------------------- This program and code are copyrighted material of the Dallas Remote Imaging Group, and may NOT be copied in any fashion without the written consent of the Dallas Remote Imaging Group. Introduction: The SoundBlaster and SoundBlaster Pro audio I/O cards from Creative Labs, Inc. are very popular accessories found in many IBM PC compatible computer systems. Although the boards are usually used only to provide music and sound output for computer games, they also support audio input into the computer. The standard SoundBlaster supports mono audio I/O and is available in the $100 price range. The Pro model supports stereo and adds a CD/ROM (SCSI) interface. It costs around $250 dollars. The boards can digitize sound at high speed and, using one of the computer's DMA (direct memory access) channels, transfer the sound samples directly into computer memory. Once in memory the sound samples are written to disk. It is this ability to digitize and record sound that enables the SoundBlasters to be used for the reception and decoding of APT satellite signals. The output of a radio receiver tuned to an APT signal is just a 2400 Hz audio tone. As the satellite scans the earth and clouds, it varies the amplitude of the tone in proportion the the brightness of the area that it is currently observing. ------- What it does: If you viewed the contents of the .VOC sample file produced by the SoundBlaster VREC program with your favorite image processing program, it would not look at all like a weather satellite photo. The .VOC file is like an exposed roll of film. Its contents must first be "developed" before you can view the image. The process of "devloping" the .VOC file contents into a weather satellite image is called DEMODULATION. Demodulation converts the recorded values of the samples of the 2400 Hz APT sine wave into their corresponding pixel values. The desired image pixel values actually represent the amplitude of each peak in the APT sine wave signal. Signal sampling theory states that if you are to do anything meaningful with a digitally sampled signal then you must sample the signal at least twice as fast as the highest frequency component of the signal. The 2400 Hz APT signal needs to be sampled at least 4800 times a second. Because the APT signal is not a constant tone, it has freqency components much beyind 2400 Hz. Also the laws of thermodynamics (and life) say that nothing is perfect as theory predicts and you really need to sample at a higher rate. If we sample the APT signal at exactly 4 times its 2400 Hz carrier frequency (i.e at 9600 samples per second), each input sample will be eactly 90 degrees (360/4) in phase apart from its adjacent samples. Using the following trigonometry identities it turns out to be particularly easy to accurately demodulate the APT samples: cos(x) = sin(90-x) sin(x)*sin(x) + cos(x)*cos(x) = 1 By substituting the first equation into the last equation we get: sin(x)*sin(x) + sin(90-x)*sin(90-x) = 1 Because each recorded sample of the 2400 Hz APT sine wave is 90 degrees apart from the next sample we can calculate the pixel value as: pixel = sqrt((sample[t]*sample[t]) + (sample[t-1]*sample[t-1])) The demodulation program just needs to read the .VOC sample file, throw away the file header information, adjust the samples for clock/DMA rate errors and DC offsets, calculate the pixel values from adjacent pairs of sample values, scale the results to values from 0 to 255, and finally write the resulting pixel values to the image file. This could be a very time consuming process when you consider that a typical 14 minute capture has about 8 million input samples and that multiples, adds, and square roots are all operations that take lots of CPU time. This is particularly true if floating point arithmetic is used. To make the demodulation program run very quickly a table of all 65536 possible combinations of adjacent 8-bit sample values is pre-computed according to the above formula. All the demodulation software then has to do in order to convert the recorded APT samples into their pixel values is look up the proper table entry. No time consuming floating point arithmetic need be used once the demodulator table has been built. Reading and writing 8 megabyte files is always a time consuming process. By always reading and writing the sample and image files in multiples of 512 bytes, the demodulation software takes full advantage of the behavior of the DOS file system. ------- Problems, problems, problems: Although the SoundBlaster is quite good at adding a little zip to the odd computer game, it is far from being a precision signal processing system. Using the SoundBlaster card for APT reception presents many problems. Fortunately software techniques may be used to overcome the problems and yield APT images that rival the best commercial systems. Using the SoundBlaster for APT demodulation presents two main types of problems: 1) Sample inaccuacies and offsets 2) Clock rate and missing sample errors Sampling a perfect sine wave with a perfect board in a perfect world should yield a series of samples with an average sample value of zero. Unfortunately the SoundBlaster circuitry usually adds a small DC offset to the recorded sample values. This DC offset can cause noise and "beat" patterns to appear in the demodulated image file. To remove the effects of any DC offset in the sample values, the demodulation software calculates the average sample value in each block of input samples. This sample bias is then subtracted from each input sample. The demodulation program is currently a bit paranoid about things and re-calculates the sample bias for each input block. It would be a bit faster to calculate the value for only the first block. If the input level to the SoundBlaster board is properly adjusted, the sample value offset does not seem to change between blocks. For easy demodulation of the APT signal we need to sample at 9600 samples per second. If the resulting image is to be properly synchronized to the satellite data this needs to be EXACTLY 9600 samples per second. PRECISELY EXACTLY 9600 samples per second. How exact? A typical fourteen minute satellite pass requires an accuracy of around one part per 10 million... 9600.0000 samples per second. Typically a satellite scans one line of pixels every 1/2 second (120 lines per minute). At a sample rate of 9600 samples per second, a 14 minute satellite pass generates about 8 megabytes of data. If the sample clock rate is only accurate to a mere one part per million, the resulting image will be skewed 8 pixels from top to bottom. Although 8 pixels of skew across of screen of 4800 pixel lines is only about a .1 percent skew, it is noticeable if you are looking for it or are wanting to do some quantitative analysis of the satellite orbit from the doppler bow. How accurate is the SoundBlaster clock you ask? It turns out the closest that you can set the sample rate is around 9620 samples per second... an accuracy of around one part in a few hundred... not even close. To make matters worse the clocks on any two SoundBlaster boards can easily differ by parts per thousand. Clock errors of this magnitude cause the image to appear like a TV set that has lost sync. The image is an unreadable mess of slanted bars. The DMA circuitry on the SoundBlaster boards can automatically transfer blocks of up to 32768 signal samples into the computer's memory without using any CPU time. Once a block of samples has been DMAed into memory, the recording software starts DMAing the next block of samples into another memory area. While the second block of samples is being received, the recording software writes the first block to the computer's hard disk. The process alternates in a ping-pong fashion between reading samples into one buffer while writing the other buffer's data to disk. Unfortunately a few signal samples are lost in the time between the end of one DMA block and the startup of the next DMA block. To make matters worse the number of samples lost depends on the computer system's CPU type and clock rate. Faster systems loose fewer pixels between blocks. Also number of pixels lost seems to depend upon whether the block is an ODD or EVEN numbered block. Fortunately it is possible to compensate for the errors in the clock rate and the samples lost between DMA blocks. The demodulation program compensates for the pixels lost betwwen DMA blocks by duplicating the last few samples of each DMA block. The user can independently specify the number of samples to add to (or even remove from) the odd and even numbered DMA blocks with the /O and /E command line parameters. The sample clock rate error is compensated for in two stages. The first stage is the coarse adjustment factor. This factor causes every n'th input sample to be removed (or duplicated). By throwing away every 601'st sample, the 9620 samples per second that the SoundBlaster produces is cut down to ABOUT 9600 samples per second. The coarse adjustment factor can be changed by using the /C command line parameter. The second clock rate adjustment factor is the fine tuning factor. It is used to zero in the exact timing value. It adjusts out any residual skew in the image caused by variations in individual SoundBlaster board clock generators. The fine adjustment factor works just like the coarse adjustment factor. It causes every n'th input sample to be removed (or duplicated). It may be specified with the /F command line parameter. ----------------------------- Doing it: The first step is to connect your satellite receiver to the microphone input of the SoundBlaster. You must be very careful to set the amplitude of the receiver output low enough so that it does not overdrive the SoundBlaster. If you overdrive the card its automatic gain control (AGC) circuitry will attempt to compensate. This will cause streaking in the resulting images. To properly set the receiver level use the VEDIT2 program supplied with the SoundBlaster card. Select the SCAN INPUT item from the RECORD menu. This will show a graphical representation of the input signal. While monitoring a good satellite pass adjust the receiver level until none of the signal peaks touch the top or bottom margins of the graph. Leave a little safety margin (1/8 inch) just to be safe. Once the receiver level has been set, the next step is to record a satellite pass to disk. This is done with the VREC program supplied with the SoundBlaster card. For the SoundBlaster Pro use the command: vrec c:cap /a:mic /m:mono /f:low /s:9620 /l:15 /t:840 where: c:cap - is the name of the file that you want to write the samples. Remember the sample file will be quite large. Around 600 Kb per minute of recording. In this case the samples will be written to the file C:\CAP.VOC /a:mic - selects the MICROPHONE input. /m:mono - selects MONO recording. /f:low - sets the LOWPASS recording filter. /s:9620 - sets the recording sample rate to 9620 samples per second. Note the if you ask for values less that /S:9619 the VREC program rounds the value down to around 9500 samples per second. /S:9620 is the smallest value that actually selects a sample clock greater than 9600 Hz. /l:15 - sets the microphone level to full open. Use the receiver output level control to adjust the recording level. (I don't think this is what this does or is necessary any more. It is left over from early attempts to get rid of hum in the image caused by a bad cable) /t:840 - says to record for 840 seconds (14 minutes). This value can be adjusted to whatever length is desired. After a satellite pass has been recorded and written to disk as a .VOC or .WAV sound sample file, the next step is to demodulate the sound sample file into an image file. Use one of these commands: sbdsp c:cap.voc c:cap.img (SoundBlaster) sbdsp c:cap.wav c:cap.img (ProAudio) This will read the recorded sample file C:CAP.VOC or C:CAP.WAV and write the resulting image to the file C:CAP.IMG (remember that these files will be about 8 Megabytes EACH). If you do not specify the output file name, the demodulation program will ask if it is OK to write the output image over the data in the .VOC file. This is a VERY time consuming process, but can be useful if you are short on disk space. Note that if you choose to overwrite the input data file, you cannot experiment with the various timing adjustments or interrupt the demodulation program. Once the input file has been demodulated you can use your favorite image processing program (such as IMDISP, APTCAP, or SATVIEW) to view the resulting image. The file written by the demodulation program is raw binary 8-bit gray scale image. Each line is 4800 pixels wide. A 14 minute pass has 1680 scan lines. (Because of the timing adjustments, etc the output image may be short a few lines). --- Tweaking in the timing: What you should see is the APT image complete with the normal "doppler bow" curve. The curve in the image is due the speed of light. Since light travels at 186,000 miles per second, each pixel of image shift in the doppler bow (1/9600 of a second) represents about 19.4 miles of satellite movement relative to the receiver. As the satellite approaches the receiver the radio signal has to travel less and less distance to reach the receiver. As the satellite moves away the radio signal takes longer and longer to reach the receiver. The point in the doppler bow where the curve changes slope is the closest point of approach of the satellite pass. In a properly adjusted image, the shape of the doppler bow curve should appear symmetrical about the closest point of satellite approach. If the image is slanted more towards the left or right, or appears like a TV image that has lost sync then you will need to adjust one or more of the timing adjustment factors. Usually only the fine timing adjustment (/F) needs to be set. To get an idea of the magnitude of the adjustment needed, count or estimate the number of pixels that the image slants. (Hint: use the pan and zoom features of your image display program. If your display program re-sizes the image to fit the screen, remember to count pixels in the FILE, not those on the screen). Divide the total file size by the number of pixels that the image slants from top to bottom. adjustment factor = (file size / pixels of image slant) The more the severe image slant is, the SMALLER the timing adjustment factor value. Subtle image slants are typically corrected with large valued adjustment factors (say 50,000 - 500,000). Adjustment factors in the thousands would be used for images that slant a good portion of the width of the screen. Even more severe slants first should be corrected by tweaking the /C (coarse) timing adjustment. Images that slant to the left use a positive adjustment count. Images that slant to the right use a negative adjustment count. ->| |<- estimate the number of pixels of image slant | | | ---------- ---------- | / / \ \ | / image / \ image \ | / / \ \ | ---------- ----------- Use /F+value Use /F-value The loss of pixels between DMA sample blocks shows up as small periodic jags in the image of a pixel or so every 6-8 scan lines. Experiment with the /O and /E command line options may be to minimize these remaining jaggies. For these options, larger values produce greater effect. The maximum DMA adjustment factor possible is +/- 255. Only + values should be needed here. The software supports - values just in case... The image may look OK except for one or more large and sudden shifts or discontinuities. These shifts usually occur on systems with slower hard drives or CPU's. The cause is usually the excessive time it takes DOS to extend or otherwise allocate disk space as it writes the .VOC/.WAV file. If this occurs in your images, it can usually be fixed by recording the sample file to a freshly "defragmented" disk. Use a disk optimizer program like Norton Utilities or PC Tools to pack the sample file hard disk drive before running the VREC or RECFILE recording program. Once the proper timing adjustment factors have been determined for a particular computer, they should not need to be changed (except possibly for a drift in the SoundBlaster sample clock rate with temperature). A batch file can be created that will automatically use the appropriate timing factors. -------- Updates for using SBDSP with the MediaVision ProAudio Spectrum boards: Version 1.1 of SBDSP now supports demodulation of 8-bit audio .WAV files such as those produced by the MediaVision ProAudio Spectrum and PAS-16 boards. To use the MediaVision boards you should connect the receiver to the left channel of the LINE input jack. The MICrophone input seems to compand or otherwise mess up the audio samples (just backwards from what the SoundBlaster seems to do). Mediavision does not seem to supply a recording level monitor program like VEDIT2 that can be used to adjust the audio input level graphically. Experimentation is the order of the day here. On my system I turn down all the MIXER inputs from the "PAS *" command except for the EXTERNAL input jack. I turn this one up ALL the way and connect a receiver that produces a 1.0 Volt peak-peak audio output. This seems to produce demodulated files that have values ranging from 0..160 or so. A little more input level would be nice but my all my receivers have their outputs fixed at the 1.0 V level required by my A&M (R.I.P) demodulator board. If your images are excessively dark crank up the input volume. If they are too light or distorted or have noise bars, crank down the input level. The line input of the PAS boards is designed for 2.6 V signals. To record a pass for the MediaVision ProAudio Spectrum 16 board use the command: recfile c:cap.wav r9658 8 where: c:cap.wav - is the name of the file that you want to write the samples to. Remember the sample file will be quite large. Around 600 Kb per minute of recording. In this case the samples will be written to the file C:\CAP.WAV You must manually stop the recording because RECFILE does not have a record timer feature. r9658 - sets the recording sample rate to 9658 samples per second. Note the if you ask for values less that R9658 the RECFILE program rounds the value down to around 9500 samples per second. R9658 is the smallest value that actually seems to select a sample clock greater than 9600 Hz. 8 - forces 8 bit recording (supposedly the default but let's be a bit paranoid...) Everything is then the same as with the SoundBlaster except there should be no need to use /E or /O DMA block adjustment factors. The MediaVision boards do not seem to lose samples between DMA blocks. Also the .WAV file format does not have any internal markers that indicate where DMA blocks begin and end. ------- There are a couple of new command line options in version 1.1: /I - produce an output files with inverted pixel values (i.e. swap black and white). Very useful with the Infrared (night) imager on the Russian Meteor 3 series satellites. /S=scale - Use to adjust the output pixels for the full dynamic range of 0..255. If the pixels in the demodulated images only cover a portion of the desired range of output values, then this value can be increased. The default is 255. For example if the output images only have pixels with values from 0 to 128, a value of /S=512 could be used to boost the results to 0..255, etc. Finally SBDSP 1.1 also supports raw binary input files. These raw binary files should not have any embedded control information or headers. A header at the beginning should not cause any major problems and would be demodulated as data. Raw binary files MUST have a .BIN extension. Normally the files should contain samples with values centered about 128. To demodulate files that have normal signed eight bit values centered about 0 use the (untested) '/Z' option and hope for the best. Dallas Remote Imaging Group BBS ====> 214-394-7438 RECEIVING WEATHER SATELLITE IMAGERY: A BEGINNER'S PRIMER -------------------------------------------------------- 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 John DuBois, W1HDX, VAS/HRPT Design Engineer T S Kelso, Air Force/NASA liaison Ed O'Grady, Soviet Space Program Analyst Mark Sims, Director Software Development 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) Dayton HamVention '91 (rev 14) Tom Gentry, K5VOU, has been kind enough to help us 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 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 Meteorological Satellites/METEOR. The Chinese satellite Feng Yun transmits on 137.795 when it is operational. 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 - see March 1991, '73 Amateur Radio Today' article for a description of this procedure. 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 is now available from the ARRL. 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 Schwittek MULTIFAX or the MULTIFAX MAP software which runs on the IBM PC. The PC interface hardware is available as printed circuit board alone, board and all parts, or completely assembled. Additional image processing software is available online DATALINK. The units available from David Schwittek, Ralph Taggart, Jerry Dahl, GTI Electronics and Quorum communications listed under Sources are all well worth investigating if you are just getting started. You can obtain directly from DATALINK the MULTIFAX MAP interface hardware designed by Jim Bartlett and David Schwittek. '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 separate 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 Canadian Space Society BBS, 416-458-5907, 2-Line Elements maintained | by Ted Molczan of 600+ satellite - Visual satellite tracking info | 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 PASSCHED.ZIP, SEESATxx.ARC, TRKSAT.xxx and others CELESTIAL RCP/M, TS Kelso, 513-427-0674, PASSCHED.ZIP or SEESATxx.ARC Astronomical Data Service, Rodger Mansfield, 3922 Leisure Lane, Colorado Springs, CO 80917-SPACE BIRDS program and Newsletter, $40. Paul E. Traufler, 111 Emerald Drive, Harvest,AL 35749-TRAKSAT Satellite | Tracking program-Non - Registered $10.00, Registered Version $25.00. | Bill Bard, 1732 74th Circle NE, St Petersburg, FL 33702, MACSAT | tracking program for the Apple Macintosh - $10.00 for disk and manual. | RPV Astronomy BBS, Dave Ransom, 213-541-7299, STSORBIT Tracking program | and latest version of TRAKSAT and NASA Prediction Bulletins online. | 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, 1020 S. Main St. Suite A, Grapevine, TX 76051, phone 817-488-4861, BBS Dataline 817-421-0228 | Scanner Modification, See March, 1991 '73 Amateur Radio' Magazine for | 'Weather Satellite Reception' article by John E. Hoot, page 12. | Crystals: JAN Crystals, 2400 Crystal Dr, Fort Myers, FL 33906-6017, phone 1-800-237-3063 or 813-936-2397 Pre-Amps: Quorum Communications, 1020 S. Main St. Suite A, Grapevine, TX 76051, Spectrum International,Inc., Box 1084, Concord MA 01742, phone 508-263-2145 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, David Schwittek, 1659 Waterford Road, Walworth, NY 14568, phone 315-986-2719, Multifax 5.x and 4.x for VGA, 3.x for EGA on the IBM-PC. This is the original 16 color system, see Multifax MFMAP. 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. Weather Satellite Handbook BBS, 517-676-0368, Ralph Taggart. | 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 Multifax MFMAP, Elmer and David Schwittek, 1659 Waterford Road, | Walworth, NY 14568, phone 315-986-2719. MFMAP software for the IBM PC | and the Jim Bartlett/David Schwittek/DATALINK interface card for | APT/GOES/FAX. This is a fully functional 8 -bit / 256 color system | with image data captured directly to disk at 4800 or 3600 samples per | second. Additional software is available online DATALINK and Kelso's | CELESTIAL BBS - download APTCAPxx.ZIP and IMDISPxx.ZIP. | 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 article contain an excellent list of hardware and software sources. The completed card can be ordered directly from | Jerry Dahl, OFS Software, 6404 Lakerest Court, Raleigh, NC 27612, | phone 919-847-4545 | WeatherFAX-GTI Electronics, 1541 Fritz Valley Rd, Lehighton, PA 18235, | has a complete line of satellite receiving equipment, | George Isleib, phone 717-386-4032 | Complete Systems - Hardware and Software: Dallas Remote Imaging Group P.O. Box 117088 Carrollton, Texas 75011-7088 214 394 7325 Complete Earth-Scan AMIGA turnkey system ready to put on air 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 Communications and the YU3UMV printed circuit boards are available from Fred Sharp 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, 1020 S. Main St. Suite A, Grapevine, TX 76051, phone 817-488-4861, BBS Dataline 817-421-0228, offers a fully integrated systems 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. Quorum also sells the | AVHRR/HRPT system designed by John DuBois and Ed Murashie. | Spectrum International,Inc., Box 1084, Concord MA 01742, phone | 508-263-2145, is the U.S. representative for Timestep Weather Systems | SSC/Software Systems Consulting, 150 Avenida Cabrillo, Suite C, | San Clemente, CA 92672 - PC HF Facsimile and PC GOES/WEFAX software | and complete receiving systems, phone 714-498-5784 | Satellite Meteorology: Satellite Imagery Interpretation for Forecasters - 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 Conference 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 Review DATALINK RBBS bulletins for current information ====> 214 394-7438 DALLAS REMOTE IMAGING GROUP - DRIG Voice: 214 394-7325 Data: 214 394-7438 P.O. Box 117088 Carrollton, TX 75011-7088 ATTENTION: Jeff Wallach, Chairman | New or Changed Items = | |