Video signal on spare Fathom tether conductors

General Discussion
1

Hi all ,

On Bluerovs running on Fathom-X , have you ever used the spare tether conductors to run multiple video signals ?
I.e. adding two cameras ( with or without video baluns ) and running the video signal on two separate twisted pairs on the Fathom tether .

Any interferences ? any problems ?

Thank you
Davide

2

Davide,

I run the Fathom-X, Fathom-S for a second camera, and RS-485 (TX/RX) across the two other pairs through a 100m of Fathom tether without issues.

Ken

3

Thank you for sharing Ken.

If used only to run the 2nd cam , wouldn’t a video balun do the same as a Fathom-S , for a fraction of the price ?

Davide

4

I sometimes run a similar setup to Ken. I have RS-485 half-duplex on one pair, video from a passive balun (to an active balun on the topside) on a pair, and ethernet via the fathom-x on another pair. I do not use the Fathom tether, but it has similar construction with 4 unshielded pairs.
I do notice some noise in the live video signal that uses the balun, and it is caused by the Fathom-X, but its not too bad.

5

Thank you Nathan .

On what tether length are you running ?

Can I ask why do you need an active balun on the topside ? are you having better results than using two passive ones ?

Thank you very much .
Davide

6

In this case I have about 1500’ of the tether on a winch. I have tested every combination of balun, but using the passive to active setup gave the best, most stable video output at the surface at this distance.