aww shucks, thank you for all the tips and encouragement. I suppose I have been doing a silly thing really because I am tempted to come up to the surface as an 'invisible watcher' in freeview ( is it?) just to see what is going on, and up there, separated from the sub, you can't hear the pings... I wondered if the pings were MY pings bouncing off them,like with computers, but seems not, t'other way around... oh dear. A lot to learn, but, I shall be back there in a bit to have another go
