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Spring 2004 Issue |
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Slow Scan TV in Space |
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In this article the authors take
us from the |
Gennadiy Padalka talking to amateur radio operators in the U.S. Over his left shoulder can be seen the SSTV system. The large, square white image is the 5-inch LCD screen. The rectangular bluish screen just above it is the SSTV transmitter (Kenwood TM-V7A). |
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Amateur radio Slow Scan Television (SSTV) was conceived (invented) by Copthorne Macdonald, W4ZII, who now holds the call VY2CM. In September 1957 he began the design and construction of a low-cost SSTV system adapted to the standard amateur radio voice-channel bandwidth. This work was undertaken as a personal project in an independent problem course at the University of Kentucky.1 Cop was soon joined by Dr. Don Miller, W9NTP, who, along with others, contributed to many advancements, including color. Now, over a period of some 46 years, many systems have been devised, including standalone hardware systems and software programs working in conjunction with a computer and radio transceivers. Basically, SSTV is an arrangement wherein a photographic image is scanned and stored in memory. It is then scanned again, producing audio tones, which are transmitted over amateur radio voice channels. At the receiving end the tones are reconstructed to produce TV images of excellent quality.
Over many years of development, SSTV has been
accomplished entirely by amateur radio enthusiasts who have devoted their
time and financial resources to this mode of operation. The definition of
SSTV as provided by the FCC to W9NTP is “SSTV is the transmission of a
live picture over a voice communication channel in real time.” The idea to put an SSTV system aboard the Mir Space Station was initiated in early 1997 by Farrell Winder, W8ZCF, and Dr. Don Miller, W9NTP. After discussing a possible concept for a system, a conference call was placed to Dr. Dave Larsen, N6CO, and Miles Mann, WF1F. Both Dave and Miles were recognized for their contacts and work in providing amateur radio equipment to Mir. No funds were available for such an involved project, but generous contributions came from the Kenwood Corporation for the TM-V7A transceivers, Tasco Electronics for the TSC-7 scanners and docking stations with LCD displays, and PictureTel Corp and Apple Computer for cameras.
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