The X-Coupling systems we use in Area and the big Terminal place in the UK are not that clever - they simply re-transmit what they get. They don't wait for anything. The problem of suppresion in our systems (not knowing anything of the details of Manchesters stuff I can't comment) shouldn't happen. It can, however, cos a strong RF signal from one A/C might dowse down a small RF signal from another on a different frequency, but the system is designed to let it all just pass through. I'm still very sceptical about the number of frequencies that can be X-Coupled at Swanwick. You can couple up to 12 together, and this can cause all kinds of problems in the way radios work and the systems we use to drive the radio equipment. But, people alot clevererererererer than me designed it and say it works. Who am I to argue? And why would they listen to a little person like me who actually has practical experience on the stuff? Ring any bells anyone?