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Technical articles

09.07.2012

Advantages of new baluns

 Due to the fact that the standard video balun features DC-continuity, one must be careful about ground loop problems. If there is a ground loop problem current  may flow between the CCTV camera and receiving multiplexer or DVR. By the way the coil inside the balun may be overheating and fail.

 

 Video that shows advantages of video baluns by RD ALFA Microelectronics

 

 

A classical example of such interference is a system in which several cameras are used with a single central power supply unit (PSU).

balun ground loop issues multy camera

 Upon use of the common power source, current from the camera 1 penetrates into the video line of the camera  2 via the circuit consisting of the output impedance of the PSU that is common for all cameras via the common ground camera – transmitting balun. The standard receiving balun does not reject this low frequency interference current and the image of this camera is distorted by a hum and buzz.

 

Increase in the number of cameras which are connected to the central power supply unit (PSU) worsens the situation even more. Using video balun TWIST-P1 for transmission of video signals and DC supply via one UTP cable and use of the centralised PSU, will not cause problems due to occurrence of "ground loops".

 

 Good interference rejection ratio in the low frequency range of the video signal (not less than  40 dB ) will boost quality of your video surveillance system, minimizing  risk of interference in case of a change of  current consumption due to activation of infrared LEDs  on the cameras.

balun ground loop issues multy camera twsit-p1

 

More info about TWIST-P1 available here.

 CTO Alex Maiboroda, alexander.maiboroda@rdalfa.lv

 

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