Interference on AVTECH 4CH DVD

My 4CH DVD is located in the garden and I run a Cat6 cable to the house, about 50m. I suffer from inteference occassionaly, especially at night. This is thick lines go (going from bottom to top). They are not strictly horizontal and are translucent. This is probably cause by bad or no eathing and due to interference from electrical cables in parallel. Are there any quick fixes?
I also don't know how to set the recording sensitivity LS SS TS RE. I don't have a handbook so don't know how to set these parameters.
My webcam is http://chanakanmansion.dyndns.info:90/ ID admin PW admin
Please remember I'm in Thailand so the time is GMT + 7
Thanks - Jeff

[scorpion]

For those of you who need a manual then there are some here, and they are in various languages, and there are the various Video Server E versions

http://scorpiontheater.com/cpcamtechsupport.aspx

http://scorpiontheater.com/troubleshooting.aspx


You can google scorpiontheater if the links have been removed by the mods.