Waveforms of the experiment signals at different ranges, where the receiver depth is 1111 m and the receiver ranges are (a) 59.6 km (the reference signal), (b) 47.2 km (the correlation is 0.92), (c) 48.9 km (the correlation is 0.84), (d) 51.0 km (the correlation is 0.74), (e) 49.4 km (the correlation is 0.47).