Comments on: Video over UTP active adapters

By: Tomi Engdahl

Tomi Engdahl — Tue, 31 May 2022 10:30:35 +0000

Twisted-Pair Transmission of Closed-Circuit Video Made Easy
https://www.analog.com/en/technical-articles/twisted-pair-transmission-of-closed-circuit-video-made-easy.html

With the pervasive adoption of twisted pair infrastructure for in-building communications, developers of closed-circuit television (CCTV) systems face increasing pressure to utilize this popular medium. Twisted-pair cabling (Category V, commonly known as CAT5, being the prevalent example) offers the end user many more signals per cable pulled and reduced termination costs compared to traditional coaxial-cable (coax) solutions.

The technical drawback to twisted-pair transmission, especially with commonly used unshielded-twisted-pair (UTP), is the tendency for common-mode noise pickup to degrade the video quality at the receive end amplifier. This receiver issue is effectively eliminated by using the LT6552 differential-input amplifier, due to the very high common-mode rejection-ratio (CMRR) of the part at high frequencies. The LT6552 also provides cable-driving output capability, thereby simplifying both the conversion of camera coax signals into twisted-pair transmissions and twisted-pair signals back to coaxial.

By: Tomi Engdahl

Tomi Engdahl — Sun, 16 May 2021 16:58:42 +0000

http://www.savel.org/2007/10/26/video-over-utp/
https://electronics.stackexchange.com/questions/331050/clamper-for-easy-dc-restore-in-video-composite

By: Tomi Engdahl

Tomi Engdahl — Sat, 05 Dec 2015 13:02:08 +0000

Here’s a useful PDF document that discusses signals, cables and connections.
http://www.kramerelectronics.com/downloads/manuals/cable.pdf

By: Tomi Engdahl

Tomi Engdahl — Sat, 05 Dec 2015 13:01:37 +0000

Increasing cable length in precision video applications
http://hackaday.com/2015/12/04/increasing-cable-length-in-precision-video-applications/

Transmitting video signals over long distances can be tricky. Cheap co-ax cables won’t do the job. You either need amplifiers along the path, or need to use expensive, high quality shielded co-ax cables – both of which can end up costing a lot. [Maurizio] built a low cost solution to transmit video over long distances using twisted pair cables.

The system is cheap and uses readily available parts. The idea is to convert the video signal into a differential output using a pair of op amps and transmit them over a pair of twisted pair wires, then extract the signal at the receiving end using another amplifier.

This symmetrical configuration renders the system immune to external noise. The design was tested for transmitting video on inexpensive CAT-3 twisted pair wire. According to him, when transmitting on 300m of wire, good quality color video was displayed on a monitor with an NTSC input. He used LMH6643 op-amps for this experiment, but other devices with similar characteristics can be used.

http://dev.emcelettronica.com/increasing-cable-length-in-precision-video-applications