Obrazový vysielač/prijímač: 1VP-B (uhlový, BNC, 2ks)

TR- 1B(k) vysielač/prijímač (pasívny transformátor) bol určený na prenos obrazového signálu - z/jeden výstupný obrazový signál/vstup - cez krútený kábel (UTP, FTP, STP). Kvôli uhlovému tvaru sa dobre spája so zdrojovým zariadením alebo prijímačom signálu (môže byť zapojený v každý smer).
Transformátor odpovedá impedancii koaxiálneho káblu (75 ohm) do impedancie súmerné linky (100 ohm), zaisťuje riadny prenos obrazu cez vzdialenosť až do 400 m (kategórie 5 kábel).

Inštalátor by mal venovať pozornosť pri spájaní k správnym vývodom: (+) (+) a ( - ) ( - ). Nevhodné spojenie vedie k poruchám obrazu.

CMRR in video transformers (baluns). "Balun" is the short for "Balance-Unbalance", in CCTV applications meaning a transformer for changing the transmission medium from a coaxial cable to a twisted pair, and vice versa. The biggest advantages of using balanced transmission cables are lower costs, higher resistance to external interferences, and possibility of using longer transmission lines. Due to identical arrangement of the two wires of a balanced line, the interferences are also the same and can be cancelled in a differential balanced input of the receiver. It is not possible in the case of a coaxial transmission line.

The ability of a video transformer to cancel the common interferences identical in both wires is characterized by Common Mode Rejection Ratio (CMRR). It is the ratio of the error signal at the asymmetric output of the transformer to the interference on the both balance inputs. The parameter can be measured, for example, by applying high, common interference signal V_.z. to the both balance inputs (i.e. shorted, to eliminate a differential signal). Under such conditions, an ideal transformer would not provide any signal on its unbalanced output, but the real device will demonstrate a V_.b. value. The CMRR is calculated using the following formula:

CMRR = 20*LOG(V_.b./V_.z.)

The CMRR of Etrix baluns (in the 15 kHz to 6 MHz range) is 60 dB. It means that they attenuate the common signals (interferences) 1000 times.