On Sat, 3 Apr 2010 15:47:40 -0400 solarwind wrote: > Respectfully, How does that make sense? Without encryption, I have no > guarantee that someone won't bring down my balloon. And by guarantee, > I mean reasonable guarantee, which encryption provides. > > Again sorry for messy reply, sent from phone. You can use codes without encryption. Implement a handshake protocol with a challenge/reply. You don't have to encrypt for that. Send a 64-bit code sequence. I'm sure nobody will find it out before launch. You can also transmit visible packets with a special, non-standard CRC protocol. The contents of the packet could still be clear-text. You could also use the bands which are reserved for remote-control, where nobody normally _listens_ to the transmissions. John -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist