Chirp signalling offers

modulation scheme for underwater communications Edit J. Kaminsky Information contained in the slope of chirp signals can be employed for digital underwater acoustic communications across a broad range of applications. Wireless communication can be conducted in the underwater acoustic (UWA) channel through sonar signalling. We propose using the frequency-vs-time slope of sonar ‘chirps ’ to transmit information in a robust scheme for a spread-spectrum underwa-ter communications system. Digital data can be represented by the slope of chirp signals. In the simplest binary case, an ‘up ’ chirp (i.e., a signal with instan-taneous frequency that linearly increaseswith time) represents a ‘1 ’ and a ‘down ’ chirp represents a ‘0’. Higher-dimensional con