AmateuRadioMalaysia

Friday, March 24, 2006

Wanna start AMateur TV?

Show the family, the shack, projects, etc. Since the lower the
frequency, the farther the distance, given the same power
and antenna gain, the 70 cm band is where 98% of ATVers
operate - it is also the lowest cost and easiest to get on.
The 902-928 MHz band goes half the distance and so on.
ATV frequencies work best with an unobstructed line of
sight path between the transmitting and
receiving antennas. So the antenna and height is the most
important part of the ATV station. Antennas need to be made
for the 70 cm band, preferably as high of gain as possible and
the same polarity as is standard in your area. Low loss coax
is also a must as it takes 150 to 200 microvolts into your receiver
for a snow free picture and you don't want to throw RF away
unnecessarily.

To see your first picture it may be as easy as turning your cable
ready TV to cable channel 57 thru 60 and connecting it to a good
outside 70 cm antenna of the same polarity as is used in your
area by ATVers. It doesn't get any cheaper or easier
than that to enjoy another of the many modes in Amateur Radio.
Make sure your TV tuner is switched to cable channels when you
try it. Unlike slow scan TV - SSTV - ATV standards are the
same as broadcast TV and your camcorder so your TV set is
your receiver without the need of any computer or other black
box interface. However, the 70 cm, 420-450 MHz band is the
first ham band that has wide enough bandwidth for ATV and
therefore can best be seen between antennas with line of sight.

Amateur Television, ATV, is fun and easier than you might think
to get on with all kinds of applications.
Besides sending and receiving live action color video between
home ham stations much in the way you are probably
used to with voice on two meter FM, there is; televising live or
from tape your ham radio club meetings to those
who could not make it in person; showing critical locations to
local emergency service groups during actual
disasters, parades or races; seeing Space Shuttle video and
audio if some one is repeating it from their satellite
TVRO; seeing the edge of space from amateur balloons or
rockets as high as 100,000 ft.; getting a pilots view from
a camera in a R/C model aircraft or real airplane, and much more.

Any camcorder or camera can simply plug its composite video
and line audio into the ATV transmitter. It can be color or
black and white - what ever you plug in is what you get out.
Composite NTSC video is the standard A/V output in
the USA for camcorders. As an alternative there are many
small low cost color or black and white cameras available now
that are made for computers or security
under $200 that can be used at the home station, mobile,
portable, R/C, balloon or rocket ATV.

1 Comments:

  • Hi,
    I would like to share this info in commenting to the posting:

    "The 902-928 MHz band goes half the distance and so on."

    Its unfortunate that this range is not available for use in our country to play with ATV or using for wireless sender. I know of cases where there had been cases of local companies who got cheated with CCTV installers by selling them this 900Mhz system and MCMC Enforcement officers would seize the units and compound the users.

    Another element to take note about ATV is the emission codes. If my memory serves me right, the code is referred to C3F, and referring to my Apparatus Assignment, this emission mode is only allowed in 1240Mhz and above.

    So, if amateurs are serious about playing it in the UHF band, then something ought to be done, e.g. forming what is known as SIG (Special Interest Group) and debate the issue and submit a proposal to the authorities.

    I will be more than glad to assist not as MARTS or ASTRA or MARES, but as an Elmer who knows about the needs and wants of amateur radio.

    73 de 9M-10298

    By Blogger 9M-10278, at 11:52 AM  

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