Doppler Effect in the Underwater Acoustic Ultra Low Frequency Band

We address communications between Autonomous Underwater Vehicles (AUVs), Underwater Sensors (USs) and remote operators. We assume the use of acoustic waves. Due to the Doppler effect, the communication frequency depends on the relative motion between the participants. We are interested in the Ultra Low Frequency (ULF) range, from 0.3 to 3 kHz. We relate the Doppler effect to the half-power bandwidth, versus distance. Numeric simulations are conducted. We show that the Doppler shift is significant with respect to the half-power bandwidth in the ULF band, for long distance communications.