Compensate ADP signal strength for spherical spreading.

beamUnspreadAdp(
  x,
  count2db = c(0.45, 0.45, 0.45, 0.45),
  asMatrix = FALSE,
  debug = getOption("oceDebug")
)

Arguments

x

an adp object.

count2db

a set of coefficients, one per beam, to convert from beam echo intensity to decibels.

asMatrix

a boolean that indicates whether to return a numeric matrix, as opposed to returning an updated object (in which the matrix is cast to a raw value).

debug

an integer specifying whether debugging information is to be printed during the processing. This is a general parameter that is used by many oce functions. Generally, setting debug=0 turns off the printing, while higher values suggest that more information be printed. If one function calls another, it usually reduces the value of debug first, so that a user can often obtain deeper debugging by specifying higher debug values.

Value

An adp object.

Details

First, beam echo intensity is converted from counts to decibels, by multiplying by count2db. Then, the signal decrease owing to spherical spreading is compensated for by adding the term \(20\log10(r)\), where \(r\) is the distance from the sensor head to the water from which scattering is occurring. \(r\) is given by x[["distance"]].

References

The coefficient to convert to decibels is a personal communication. The logarithmic term is explained in textbooks on acoustics, optics, etc.

See also

Examples

library(oce) data(adp) plot(adp, which=5) # beam 1 echo intensity
adp.att <- beamUnspreadAdp(adp) plot(adp.att, which=5) # beam 1 echo intensity
## Profiles par(mar=c(4, 4, 1, 1)) a <- adp[["a", "numeric"]] # second arg yields matrix return value distance <- adp[["distance"]] plot(apply(a,2,mean), distance, type='l', xlim=c(0,256))
lines(apply(a,2,median), distance, type='l',col='red')
legend("topright",lwd=1,col=c("black","red"),legend=c("original","attenuated"))
## Image plot(adp.att, which="amplitude",col=oce.colorsJet(100))