44

9 SPECIALIZED COMMUNICATIONS

SLOW SCAN TV/ FACSIMILE
Slow-scan Television (SSTV) is a popular application
for transmitting still images over the air, from one
station to another. Instead of trying to describe your
station, simply showing it is much faster. Transmitting
images over the air requires a scan converter,
besides a transceiver. A scan converter transforms
images taken with a video camera into audio signals
that can be fed into your transceiver. The recipient’s
scan converter transforms audio signals back into
video images so that he or she can view them on a
TV set.
Nowadays instead of a scan converter, many hams
use a personal computer, a software application, and
an interface attached to the transceiver. This is much
cheaper, more flexible, and does not require a TV set.
In recent years, many low cost digital cameras have
become available. You can transfer images from
these cameras into your computer.
For further information, consult reference books about
Amateur Radio. The frequencies (measured in kHz)
commonly used for SSTV operation are listed below:
adanaC/.A.S.U 1noigeRURA
)acirfA/eporuE(
7583,54830473~0373
17175407~5307
33241,0324153241~52241
0431254312~53312
0868258682~57682
005541—
Fax (facsimile) is one of the original image
transmission modes. Using this mode allows you to
exchange more detailed graphics than SSTV.
Amateur Radio fax functions much like old analog fax
systems. It scans paper and converts acquired
image data into a series of tones representing white
and black portions of the image. Because fax
requires longer transmission time, you should use it
only when band conditions are stable with strong
signals.
Popular fax frequencies include the following:
•7245, 14245, 21345 (International Net), and
28945 kHz
Operating on SSTV or fax mainly involves learning
the functionality of your computer application or
accessory hardware that supports these modes.
Consult the instruction manual that comes with your
software or accessory equipment.
Note:
When operating either SSTV or fax, use a fast AGC setting
and switch OFF your Speech Processor, for best results.