I have an application which requires **sending** PAL video signal & UART infomation over a **50R coaxial cable** without disrupting the PAL protocol while doing it, the total length of the cable is around **200 meters or 656 ft**. 

I have already decided how to **multiplex** this signal over the PAL, my issue is that I will need to send signal from both ends of the cable without **dirupting** the controlled impendance and typical methods for cable termination are not suitable for me.

What I come around, is a design involving drivers with a **shutdown pin** to let me **"disable"** the 50R. Since the receivers have **"always-on"** termination I wanted to control them too so I added some **BJTs** (still don't know if it's a good design or MOS needed) controlled by some GPIO from a microprocessor which can **"translate"** the line number, if it's HSYNC or VSYNC and so on.


In case somebody wants to take a deeper look: 

 - **Driver** **->** LMH6722(w/SH) - [Datasheet][1]
 - **Receiver** **->** same just configured as a Schmitt Trigger for level translation


Can somebody recommend me a better termination technique which I could use ? Also I cannot use two coaxial cables for each line, **only** half-duplex.

This is just a design, not tested yet, waiting for a second opinion. **:)**

[![Final Design][2]][2]


  [1]: https://www.ti.com/lit/ds/symlink/lmh6722.pdf?ts=1623668642080&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FLMH6722
  [2]: https://i.sstatic.net/73Zij.jpg