Rate-Range for an FH-FSK Acoustic Modem

Signals transmitted through underwater channels experience attenuation due to dissipation of acoustic energy by spreading as well as by absorption. The path loss due to absorption is found to be highly dependent upon the frequency. Ambient noise, which also greatly affects accurate reception of the signal, is also highly dependent upon frequency. For these reasons, the received SNR cannot be assumed to be constant over wideband acoustic signaling schemes. In this paper, the authors determine the (signaling) rate vs. range curves for a FH-FSK modem considering the frequency selective nature of signal attenuation in an acoustic medium.