Deep-water Black Box Retrieval - November 2009, Volume 13, Number 09 - Archive - Hydro International
The maximum detection range is determined primarily by the frequency and the transmission power, with an initial source level of 160.5dB re 1µPa @ 1m, which reduces to 157.0dB re 1µPa @ 1m, after 30 days. The quoted maximum detection range is 2-3km, although this is influenced by environmental conditions.