Multimedia system description
Datwyler´s CAT TV system is an active system for the transmission of video and TV signals up to 862 MHz using a class EA, F and FA star-shaped symmetrical 100 ohm cabling system configuration in structured premises cabling systems (generic cabling systems) conforming to ISO/IEC 11801 and EN 50173. In order to achieve interference-free transmission of the frequency range from 5 - 862 MHz it is necessary to use a high-performance shielded cabling system which has a very homogeneous progression of impedance after laying. For new installations we therefore recommend our AWG-22 cable CU 7150 4P Multimedia and CU 7702 4P with correspondingly high-performance connection technology. Link lengths can be a maximum of 90 metres when using an AWG22 cable.
The system comprises the CAT TV panel (19 inch) with 12 ports and integrated signal converters as well as our CAT TV baluns (balancer/unbalancer).
The CAT TV panel has a frequency range of 5 - 862 MHz and full reverse channel capability. It serves to amplify and prepare the incoming supported television signals (CATV), to convert them from asymmetrical (coaxial, 75 ohm) to symmetrical transmission mode (two-wire technology, 100 ohm) and to split the signals between the panel´s 12 output ports (RJ45 ports). Thus, while maintaining the maximum interference emission permitted under EN 50083-2, the CAT TV panel is able to bridge a maximum cable attenuation of 40 dB (normal operation). By increasing the output level, cable attenuations of up to 50 dB are also bridgeable with additional shielding measures (special operation). In order to comply with the relevant EMC regulations the externally connected network components must have a minimum shielding attenuation of 75 dB.
Because of great differences in level at the service interchange point, the CAT TV panel needs to be adjusted. To do this we use a level controller and an equalizer at the input. The CATV signals are initially switched through by connecting a CAT TV balun to the RJ45 port of the CAT TV panel via a control current.
Each RJ45 output port can then be individually connected to an RJ45 patch panel port by screened RJ45 patch cables (PiMF). The symmetrical data cable permanently attached to it terminates at an data outlet, also with RJ45 ports. If desired, other voice or data services such as telephone or Ethernet services can also be distributed using the same symmetrical data cable.
The CAT TV balun is connected to the data outlet by a high-performance shielded RJ45 patch cable. This ensures that the symmetrical signals received via the structured cabling are converted into a coaxial signal which the device (e.g. TV set) can "understand". If telephone and HF services are transmitted over the same data cable, the signals are split and prepared in the CAT TV balun. For the telephone connection splitting is carried out to an RJ45 port, for the HF signals to coaxial ports ("IEC" for TV and radio and "F" for data).
Because the signals are more markedly attenuated at high link lengths and high frequencies than with short lengths and lower frequencies, an adjustment must take place towards as uniform a level relationship as possible. This adjustment is made at the CAT TV balun during initial start-up by means of a three-stage switch, i.e. on the "plug and play" principle.
Datwyler´s CAT TV balun can be supplied with or without a reverse channel. A type "F" coaxial port is provided at the balun output for reverse channel use with the relevant variant. All twelve incoming reverse signals are combined in the panel and together channelled to the coaxial input cable. To operate a reverse signal it is necessary to install a passive filter module in the CAT TV panel. For a safe operation with reverse signal, the commissioning must be coordinated with the service provider or his partner. Separate symmetrical signal transmission in the forward and reverse direction takes place via a pair of conductors each, making for interference-free operation.
The individual static disconnection of each of the 12 HF output ports can also be effected by way of the sub-D 15 pin port at the rear of the panel. The signals at the relevant HF output port are cut off by activating the corresponding PIN of the sub-D15 port with a TTL level = 0 to 1V (to ground).