Hal Albach :
Thanks for the link - shall give it a go.

Michael :
Yes thats a new line of thinking ( at least for me ) to use data packets instead of a singularly coded information for activating each relay using a common RF link.

The aspect of safety cannot be more emphasised. The example with the school kids is spine chilling stuff. Fortunately in my case the vehicle is Off-The-Road stuff and these OTR vehicles are not permitted to enter public roads even for short links.

Kai :
Yes with the packet schemee, I think error control becomes quite possible. Have noted your various suggestions.

Bert :
That is news - 8051 cores with RF communication facilities. Sounds interesting.

Lee Cross:
Yes the licensing part is a key issue and I am on the job. One of the resaons I want a setup that does not need licensing.

Thanks to all of you.

Raghu