| adp.beam.attenuate {oce} | R Documentation |
Convert ADP from beam to velocity
adp.beam.attenuate(x, count2db=c(0.45, 0.45, 0.45, 0.45))
x |
an object of class "adp" |
count2db |
a set of coefficients, one per beam, to convert from beam echo intensity to decibels. |
Beam echo intensity is first converted from counts to decibels,
by multiplying by count2db. Then the signals are range
corrected by adding the term 20*log10(r), where
r is the distance from the sensor head to the water from
which scattering is occuring. r is given by
x$data$ss$distance.
An object of class "adp".
Dan Kelley
The coefficient to convert to decibels is a personal communication. The logarithmic term is explained in textbooks on acoustics, optics, etc.
See read.adp for other functions that relate to objects
of class "adp".
library(oce)
data(adp)
plot(adp, which=5) # beam 1 echo intensity
adp.att <- adp.beam.attenuate(adp)
plot(adp.att, which=5) # beam 1 echo intensity
# Profiles
par(mar=c(4, 4, 1, 1))
plot(apply(adp$data$ma$a, 2, mean), adp$data$ss$distance, type='l', xlim=c(0,256))
lines(apply(adp.att$data$ma$a, 2, mean), adp$data$ss$distance, type='l', col='red')
legend("topright", lwd=1, col=c("black", "red"), legend=c("original", "attenuated"))