A mechanism to communicate in a secure manner between locomotives of a train consist is disclosed. Controllers on locomotives generate data packets and encode them according to one of a plurality of modulation schemes and transmit the encoded data packets according to one of a plurality of frequencies. The frequencies and/or modulation schemes used to transmit data are changed periodically by the transmitting controller in a sequence. The receiving controller is aware of the current frequency and/or modulation scheme being used and can, therefore, decode the transmitted data. Since the transmission frequency and/or modulation scheme is not known by a malicious actor, the data communications between the controllers is secure. The sequence of frequencies and/or modulation schemes may be communicated between the two controllers during a handshaking procedure to set up communications. Clocks of the communicating controllers may be synchronized to enable the frequency and/or modulation hopping scheme.