ok thank you for your responses.
My club has rechargeable transponder and 1 AMBrc3 decoder, no problem for personnal transponder.

24 bits is it enough ?after valid signal and 3 byte report to up, you stop the tranponder message.
we are waiting now for the Payalneg answer about the RC4 protocol!
do you want the AMB transponder rechargeable preamble ?

thanks