Have you tried turning off the cameras? I was working on a construction site, and we were having problems, it turned out the aerials on some radios were damaged which was affecting the rest, you only need one bad transmitter to stop rest working.
Reply to CCTV radio interference in the Security Alarms, Door Entry and CCTV (Public) area at ElectriciansForums.net
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc