The composite video signal is send from the tunnel to the crate (in underground gallery or on the surface). The distance varies between 100 and almost 200 meters. Because of noisy environment and large losses of video signal quality a video signal amplificator is used in the tunnel crate.

Currently two systems are in use:

• in-house development called Dual Video Differential Line Driver, which also assembles signals from two cameras as well as distributes the camera control signals; this system is powered from the surface and requires between +18 and +26 V. Schematics number: EDA-01740-V1
• Kramer 101L - a commercial product, for single line, currently tested in SPS, powered from mains in the tunnel.