Correct for Drift in an Instrument Clock

It is assumed that the instrument clock matches the real time at the start of the sampling, and that the clock drifts linearly (i.e. is uniformly fast or slow) over the sampling interval. Linear interpolation is used to infer the values of all variables in the data slot. The data length is altered in this process, e.g. a slow instrument clock (positive slowEnd) takes too few samples in a given time interval, so undriftTime will increase the number of data.

Usage

undriftTime(x, slowEnd = 0, tname = "time")

Arguments

x: an oce object.
slowEnd: number of seconds to add to final instrument time, to get the correct time of the final sample. This will be a positive number, for a "slow" instrument clock.
tname: Character string indicating the name of the time column in the data slot of x.

Value

An object of the same class as x, with the data slot adjusted appropriately.

Sample of Usage


library(oce)
file <- "~/data/archive/sleiwex/2008/moorings/m08/pt/rbr_011855/raw/pt_rbr_011855.dat"
rbr011855 <- read.oce(file)
d <- subset(rbr011855, time < as.POSIXct("2008-06-25 10:05:00"))
x <- undriftTime(d, 1)   # clock lost 1 second over whole experiment
summary(d)
summary(x)

Author

Dan Kelley