Speech watermarking for the VHF radio channel

In air/ground voice radio communication for air traffic control, an automatic identification of the 'talking' aircraft could avoid call sign confusion and ambiguity. This automatic identification can be achieved with speech watermarking, with which it is possible to transmit the aircraft identification or other data over the existing VHF radio communication link. The digital data is embedded into the existing analogue voice transmission between air traffic controller and pilot. The constraints and requirements for this application yield to a watermarking system design which does not require a modification of the existing radio infrastructure. A number of speech watermarking techniques are suitable for this purpose, of which speech perception-based watermarking is a novel approach which promises high data rates along with low audibility. The watermarking system has to be robust against the noisy radio transmission fading channel, of which the properties will be determined in upcoming flight experiments. For measuring the time-variant impulse responses of the channel, the proposed baseband measurement method allows for an inexpensive setup.