[Stuarts]

Thanks for the clarification.

Some occasional collisions may occur, as with a Davis system with multiple TX units (for extra sensors), but this will not affect the functionality of the system. If one data packet is lost, a new one with the same data, or updated data, will income within seconds (specially for wind).
The system was been fully tested with 3 TX units (maximum supported), two of them sending wind data (worst situation) and with the data relay function active.
Further tests have been done, running two systems (with different TX ID's) on the same location (at my home ), and collisions still are not a major problem.

Also I never seen a corrupted data packet. It seems data the checksum routines included on the virtualwire library are very efficient.