omnisonar_nr0a: Generates close range noise in active mode to be used for...
In arnejohannesholmin/echoIBM: Simulation of multibeam sonar data

omnisonar_nr0a

R Documentation

Generates close range noise in active mode to be used for fishery sonar. The noise is generated in non-TVG-amplified mode such that when TVG-amplified, the noise follows a pure log r-relationship, i.e., m * log(r). The term "close range noise" is here used somewhat misleading, since it is merely used to mimic the background level of a fishery sonar, which includes surface reverberation and possibly other backscattering which does not fall into the definition of noise in this system (all energy not backscattered from objects).

Description

Generates close range noise in active mode to be used for fishery sonar. The noise is generated in non-TVG-amplified mode such that when TVG-amplified, the noise follows a pure log r-relationship, i.e., m * log(r). The term "close range noise" is here used somewhat misleading, since it is merely used to mimic the background level of a fishery sonar, which includes surface reverberation and possibly other backscattering which does not fall into the definition of noise in this system (all energy not backscattered from objects).

Usage

omnisonar_nr0a(
  beams,
  SNref = -65,
  rref = 600,
  SN0 = -25,
  rjoin = 20,
  m = 2,
  TVG.exp = 2
)

Arguments

`beams`	is a list of beam configuration data, specifically (1) the average speed of sound "asps", (2) sampling interval "sint", (3) beam length "lenb", (4) number of beams "numb", (5) and absorption coefficient in units of dB re 1 m^-1 "absr".
`SNref`	is the reference noise level in dB at range 'rref'.
`rref`	is the range of the reference noise level.
`SN0`	is the noise level at zero range.
`rjoin`	is the range to the point where the transient like close range noise (passive mode) joins the active mode close range noise.
`m`	specifies the TVG shape of the noise as modeled by 10 m log(r). If m=2, the noise (except absorption) follows the clean background noise, whereas if m=0, the noise (except absorption) is flat (independen of the range form the sonar). The absorption is always present, causing decreasing signal to noise ratio (SNR).
`TVG.exp`	the TVG exponent. Set this only if the final data should have another TVG than 2.