Society UTP / Balun
Transmission is one of the most complex processes
within segment given the special CCTV
implicit in the process of sending images.
are many alternatives that are designed to
this, but there seems to be satisfied that
the immediate needs of most
integrators: society UTP / balun.
As has already been raised on numerous occasions in this environment, systems
CCTV cameras and recorders understood, are the segment "star" so to speak of the electronic security industry. Everyone thinks the capture and storage items,
but few stop to think about the complexity representael means of transmission.
The latter is a very important factor, since the quality of observing
what is happening in a facility depends largely on the medium used, because if the signal undergoes "noise" , the displayed result will not be the best.
Needless to say, the distances, as there are transmission systems video signal
are made for short extensions, while others are designed for any distance and transmission of high fidelity, but cost as a factor against, so
any integrator can not access these systems. The features described above have given to the mode of transmission over UTP a privileged place within
CCTV segment because it is easy to install and cheaper than alternatives, according to footage installed.
Arguably, this is the most widely used technology for CCTV projects in which video signals pretendeenviar, alimentaciónde PTZ cameras and controls over the same cable at distances ranging from 300 to 2400 meters.
The advantages of using UTP cable are several and described later in this report, but the reality is perhaps the most successful model for streaming video of today consists of the sociedadentre this cable and the now famous CCTV Balun.
The Balun
The term "balun" comes from English and means "Balanced - Unbalanced . It is usually a special type of transformer that plugs into an outlet "unbalanced" like a camera and the other two ends are connected to a twisted pair. These two drivers are said to be balanced with respect to land.
always need a second balun to convert back to unbalanced input
the monitor. The passive baluns need no external power source and are bilateral.
can be transmitters or receivers.
also allow the passage of data to control domes.
Coax Vs balanced lines
A coax is basically a conductor enclosed in a Faraday cage that prevents electromagnetic radiation is emitted (loss) or electromagnetic radiation is received from outside (interference). However this does not happen in the real world. There are always losses and there are always receiving interference and these problems continue to worsen between longer the cable runs.
The operating principle of the twisted pair or balanced lines is completely different.
Any interference that comes to both drivers at once be canceled because the system supports only differential-mode signals (different polarity on each conductor of the pair) because they are balanced with respect to mass. The same happens when signals.
conductor field be equal but opposite to the other driver and will cause a cancellation effect by preventing the emission and therefore eliminating the losses.
Why use twisted pair?
The twisted pair has many advantages over coax. For this reason it has been sliding in computer networks.
The continuous improvement is being done on this type of cablesbaja prices and improving quality.
The most obvious example is the cable UTP (Unshielded Twisted Pairs) at 5e widely used in LANs. With this cable you can transmit video to more than 600 meters
without amplifier. Coaxial UTP - Twisted Pair
• You can use existing multi-pair cables to be shared with other services such as alarms, telephony and data.
• Cost less than coax.
• discrete cabling indoors.
• Joints fast and economical.
• Low volume: for a single cable
UTP can send up to 4 cameras (4 pairs).
• Less waste and greater reach without amplifiers.
• Less interference.
As
The balun must be connected to twisted pair following the polarity marked.
It is essential to do this because otherwise the image is totally distorted.
Connects one at each end thus unbalanced output will increase from
(camera) a balanced (pair) and balanced again (pair) to unbalanced (monitor).
is important to remember that:
• You can not make referrals (a camera to 2 monitors). If the impedance
is not properly adapted will distort the image.
• Do not leave sections of cable connected offline. produce distortions.
• Do not mount the cable should be twisted in parallel with lines of 220 V.
The twisted pair, like the coaxial cable, is sensitive to the field generated by the wires that carry 220 volts AC. Interaction with a cable carrying 220 volts depends not only on the current circulating through the cable but also the length of the route to make parallel.
As a general rule should be separated 30 cm when the cable carrying 220 volts of low load and 60 cm when the load is high (elevators).
When the twisted pair cable must cross a line of 220 or 380 VAC High current, do so at right angles.
To give an idea of \u200b\u200bimmunity to 50 Hz fields that have baluns, a totally send 24 VAC for three pairs and video on the fourth pair of UTP to power a camera located 300 meters.
• If an image has horizontal stripes may be due to land problems. sure the cameras are erected on land. Distant lands are rarely equipotentials.
If the cameras and recording system / display are connected to different lands may be current flow between them which will be through the twisted pair distorting the image.
not use baluns to extend coaxial lines. there incompatibility between the twisted pair cable and coaxial WIRING.
As a rule there can be no more than 8 meters of coax cable between a camera
and a monitor.
For example, puedehaber 2 meters from the camera side and 6 from the monitor but under no circumstances should exceed 8 feet away. This is due to problems
impedance transformation in the higher frequencies of the video.
serious distortions are introduced in when sections of coaxial cable is too long.
and Referral joints each camera How I derive from a multicore cable or UTP?
is simple.
Used intercom cable without mesh. If the distances are very long (greater than 100 meters) using a UTP cable.
joints. soldiers must be as little as possible untwisted pair cables.
unbraided Remember that each area of \u200b\u200bUTP is a point of loss.
When using UTP cable crimping should RJ45 at each end
cable and connect them with a "keg" female-female of the type used in networks.
