>A device may be capable of communicating using at least two type types of modulation methods. The device may include a transceiver capable of acting as a master according to a master/slave relationship in which communication from a slave to a master occurs in response to communication from the master to the slave. The master transceiver may send transmissions discrete transmissions structured with a first portion and a payload portion. Information in the first portion may be modulated according to a first modulation method and indicate an impending change to a second modulation method, which is used for transmitting the payload portion.
This could be valid for any form of communication with more than one modulation system (Wifi, BT, DVB television, any recent communication system). I'm pretty sure that the modulation of the monitoring systems in a rocket will switch between transmission modes when the rocket reaches some upper layers of the atmosphere.