Compute SNR using the sonar equation
Estimate SNR from Passive Sonar Equation
Estimate the SNR of a signal arriving from a source with a source level of 200 dB. The noise level is 75 dB, the receive array directivity index is 25 dB, and the transmission loss is 140 dB.
SL = 200.0; NL = 75.0; DI = 25.0; TL = 140.0; SNR = sonareqsnr(SL,NL,DI,TL)
SNR = 10
Estimate SNR from Active Sonar Equation
Estimate the SNR of a signal transmitted by a source with a source level of 130 dB//1 μPa and reflected from a target with 25 dB//1 target strength. The noise level is 45 dB//1 μPa, the receive array directivity is 25 dB, and the one-way transmission loss is 60 dB.
SL = 130.0; NL = 45.0; DI = 25.0; TL = 60.0; TS = 25.0; SNR = sonareqsnr(SL,NL,DI,TL,TS)
SNR = 15
SL — Sonar source level
Sonar source level, specified as a scalar. Source level is the ratio of the source intensity to a reference intensity, converted to dB. The reference intensity is the intensity of a sound wave having a root-mean-square (rms) pressure of 1 μPa. Units are in dB//1 μPa.
NL — Received noise level
Received noise level, specified as a scalar. Noise level is the ratio of the noise intensity to a reference intensity, converted to dB. The reference intensity is the intensity of a sound wave having a root-mean-square (rms) pressure of 1 μPa. Units are in dB//1 μPa.
DI — Receiver directivity index
Receiver directivity index, specified as a scalar. Units are in dB.
TL — Transmission loss
Transmission loss (TL), specified as a positive scalar. Transmission loss
is the attenuation of sound intensity as the sound propagates through the underwater
channel. Transmission loss is defined as the ratio of sound intensity at 1 m from a
source to the sound intensity at distance R. For active sonar,
TL represents one-way transmission loss.
Units are in dB.
TS — Target strength
Target strength, specified as a scalar. Target strength is the ratio of the intensity of a reflected signal at 1 m from a target to the incident intensity. Target strength is the sonar analog to radar cross section. Units are in dB//1 m2.
SNR — Received signal-to-noise ratio
Received signal-to-noise ratio, returned as a scalar.
 Ainslie M. A. and J.G. McColm. "A simplified formula for viscous and chemical absorption in sea water." Journal of the Acoustical Society of America, Vol. 103, Number 3, 1998, pp. 1671--1672.
 Urick, Robert J, Principles of Underwater Sound, 3rd ed. Peninsula Publishing, Los Altos, CA, 1983.
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