When two circuits have the same potential in relation to the “Earth”, i.e. when their terminals have the same potential and exchanged signals is called balanced circuit. For example, if a terminal has the potential of 20 V the other have -20 V and the average between the two will be 0 (zero). Unbalanced circuit Already has one of the terminals connected to the “Earth” and that only one of the terminals have voltage with respect to Earth. The coaxial cable is an example of unbalanced circuit because his two drivers are different.
With that, the Balun is a device that connects these two types of circuit, the balanced (balanced) and unbalanced (unbalanced). The balun is responsible for the marriage of the impedance of the signal that is generated by the CCTV camera (balanced) with UTP cable (unbalanced signal). Through the balanced signal you can transmit the image the camera closed circuit television (CCTV), with quality, until close to the 3,000 meters, in addition to ensuring immunity against external interference and signal attenuation. The baluns have built-in features, such as passive filters, lightning protection, in addition to the transmission of audio signals, telemetry (PTZ-Pan & Tilt and Zoom) and food.
Below the difference between the two types of video converters (Baluns):
- Liabilities:in this case there is no differentiation between transmitter and receiver, it needs no power to operate and is composed of a surge protector and a signal converter.
- Active:in this case, there is the need for power (12VDC). The transmitter and receiver feature active filters and protectors, and your converted signal has a signal gain adjustment and is amplified. The receiver allows you to adjust the sharpness and brightness of the signal.
As long as the receiver is active and the transmitter converter is the passive converter, you can create an active-passive system, i.e. a hybrid system, and can install cameras at up to 2000 metres away. For signal control transmissions Speed Dome Camera data can be of type RS-232 and RS-485.
- RS-232:also known as EIA RS-232 c or V. 24 is a standard for serial binary data exchange between a DTE (data terminal Data Terminal equipment) and a DCE (data Communicator, Data Communication equipment). It is commonly used in the serial ports of PCs. (WIKIPEDIA)
- RS-485:also known as ANSI/TIA/EIA-485, TIA/EIA-485, EIA-485 or RS-485, is a standard that defines the electrical characteristics of drivers and receivers for use in balanced digital systems. The standard is published by the Telecommunications Industry Association/Electronic Industries Alliance (TIA/EIA). Digital communications networks for the implementation of the standard EIA-485 can be used effectively over long distances and in electrically noisy environments. Multiple receivers can be connected to a network in a linear fashion. These characteristics make such networks are useful in industrial environments and similar applications. (WIKIPEDIA)