| Q. |
What distance or range can I expect
with a Video Transmission system? |
| A. |
Unfortunately it depends
on a huge number of variables such as building construction, transmit power,
antenna type, height above ground and surrounding terrain. Inside, metal
shelves, filing cabinets and other metallic objects may greatly reduce
the range.
INSIDE:
You can expect a range of between 50 to 200 ft. (15 to 150 meters), inside
a modern steel building, depending on the antenna type and location.
You may have better results in brick, wood and other non-metallic buildings.
The number of floors or walls the signal will penetrate is dependent on
their composition and antenna type and placement.
OUTSIDE: Coherent
has tested its Transmitter and found that in an urban area, about 1000
ft (328 m) is realistic with a Yagi antenna on the Receiver. In a
more rural setting, a one mile (1.6 km) range is reasonable. Using
only the Rubber Duck antennas supplied, 200 ft (66 m) is possible in an
urban area and about 2000 ft (660 m) in a rural one. NOTE: For
applications outside the US, our Export Transmitters have 4 switchable
power settings and range will be considerably greater
Our advice is to borrow a
Coherent system from your local dealer and see if it works for you. |
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| Q. |
I have seen Video Transmitters priced
from less than $100 to over $15,000. What are the differences? |
| A. |
For professional applications
you want reliability, stability, a quality picture, and good sound.
The cheap "Video Senders" you may have seen, are tuned with a screwdriver,
are not crystal controlled, and drift a lot with temperature and age.
They also use AM transmission for cost reasons. Just as FM radio
sounds better than AM, FM Video gives a clearer, noise free picture.
It is also immune to interference from many more sources than AM. Avoid
all non-crystal controlled and all AM Video systems.
The Professional Video Transmitters
used by broadcasters for short range transmission cost up to $50,000
and are all FM. Coherent is using clever design and the latest highly
integrated surface mount ICs to give you virtually this level of performance
for a fraction of this price. |
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|
| Q. |
I use a Steadicam and move my
Camera around a great deal. I've tried other video links and found
that the picture breaks up all the time. What can I do? |
| A. |
Solve this problem with
our 3 Antenna True Diversity Receiver Model, CVR-1500. Use a minimum
of two Antennas spaced at least 2 feet or more apart. The CVR-1500
works by automatically switching to the strongest signal to eliminate 95%
of these problems. |
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| Q. |
What frequencies should I use? |
| A. |
If you do not fit in an
FCC regulated service such as broadcast, public utility, etc., or, you
don't want the hassle and expense of applying for a license, then you currently
have two choices.
Under FCC part 15, low powered
video transmission is allowed between 902-928 MHz and 2.4-2.483 GHz.
The 900 MHz band will yield better range than the 2.4 GHz band and
has fewer dropouts due to multipath reception problems. The 2.4 GHz
is now the standard band for Wireless computer networks (WLANs) and also
Microwave ovens.
A frequency selector switch
is a must on any Video Transmitter used in an urban area. Coherent
Transmitters and Receivers are equipped with a 10 channel selector switch. |
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|
| Q. |
Do I need to worry if a Video Transmitter
and Receiver are FCC approved? |
| A. |
Yes! You may be liable
for severe penalties and fines if caught. Note: If you see
a Video Transmitter for sale that can be received by an ordinary TV set
or tuner without its own receiver, it is not FCC approved. |
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