Page 439 - The ROV Manual - A User Guide for Remotely Operated Vehicles 2nd edition
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  432 CHAPTER 16 Acoustic Positioning
  Reception 1
Multipath reception
Reception threshold level
Noise level
Reception 2
 FIGURE 16.5
Reception threshold level.
where:
E5(SL2TL) N520log10 (NT)
NT 5 O(NA2 1 NS2 1 NR2)
with:
Distance from sound source
 E 5 received signal sound pressure in dB
N 5 total received “in-band” noise sound pressure level
SL 5 source level in dB
TL 5 one-way transmission loss in dB
NT 5 total noise pressure level in μPa
NA 5 ambient noise pressure level (noise in the environment, both natural and man-made) in μPa NS 5 self-noise pressure level (noise generated by the acoustic receiver itself) in μPa
NR 5 reverberation pressure level (reverberations or echoes remaining from previous pings) in μPa
The source level (SL) is the acoustic power, measured in decibels, transmitted into the water by the equipment.
There are two reasons why an in-band signal will not be detected: The signal is either too weak (too quiet) or there is too much noise.
16.5.1 Weak signals
There are many possible causes for a signal’s being too weak. The most common cause by far is signal blockage. The acoustic signal cannot pass through certain objects, most notably those containing
dB level










































































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