˺˺
Ground signal cables/equipment only at one
point – ie the recording system /monitoring
end. This also means not grounding
the camera bodies or brackets.
˺˺
Keep runs of cable as short as possible
and away from interference sources
such as high voltage lines.
˺˺
Use quality connectors and cables
with correct specifications.
˺˺
Use twisted pair baluns and cabling – this will
massively resist electromagnetic interference.
TIPS FOR A GREAT PICTURE
Impedance mismatching generally occurs
in long runs of cable but is also a result of
incorrectly matched plugs and cables – eg
50Ω BNC connector on 75Ω Coax cable.
This can cause oscillations and reflections in
the cable at random frequencies and this, in
turn, results in "hum bars" or ghosting. Picture
rolling or instability can also occur if these
oscillations "corrupt" the video sync signals.
Recommended Product:
TVB001 Video Transformer Filter
IMPEDANCE MISMATCHING /
LONG CABLE RUN
This occurs when cables pick up high frequency
EMI – this can even be RF. High frequency
sources can also be light switches/dimmers,
fluorescent lighting, TVs or CRT monitors, or
any other device that switches power quickly.
It can cause symptoms that range
from rolling coloured bands, to wavy,
dynamic patterns over the image.
Using twisted pair or balanced cabling is usually
the best way to combat such interference.
Recommended Product:
Doss Passive UTP Video Baluns
HIGH FREQUENCY INTERFERENCE
TVB01
VIDEO BALUN (TX)
VIDEO BALUN (RX)
VIDEO BALUN (TX)
VIDEO BALUN (RX)
TVB01
VIDEO BALUN (TX)
VIDEO BALUN (RX)
VIDEO BALUN (TX)
VIDEO BALUN (RX)
A basic Unshielded Twisted
Pair cable can be used with
passive video baluns to reduce
High Frequency Interference.
1
2
The TVB001 helps reduce
interference caused by long
cable runs and mismatched
impedances and is easy to install.
CAMERAS
DOSS DVR
DOSS VB8CH
8CH VIDEO BALUN
DOSS BP8CH12V8A
BALUN HUB W
/
POWER
100-240VAC
TO 4x CAMERAS
via
4x VIDEO BALUNS
WITH POWER
2x VPB45
VIDEO BALUNS
WITH POWER
2x VPBPP
VIDEO BALUNS
WITH POWER
UTP CAT5E (up to 300metres)
UTP CAT5E
(up to 250metres)
˺˺
Powered hub transmits power to
passive baluns for camera power
˺˺
4-in-1 input/output port on balun hubs allow 4x
camera video over a single CAT5e cable
˺˺
8CH Passive hub accepts 4-in-1 CAT5e cable
and splits them to BNC outputs/inputs
˺˺
The balun hubs work in both directions: converts to
and from BNC video and CAT5e cables. Likewise
the 4-in-1 to BNC works both ways.
8 cameras with only two UTP cables
Got interference or noise on your CCTV feeds?
DOSS CCTV Baluns with Powered Hub
Troubleshooting CCTV Video Faults
203
SECURITY & INTERCOMS
CCTV CAMERAS
B
ACCESSORIES
Free freight for Melbourne Metro orders over $99!
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