oce (version 0.1-75)

undrift.time: Correct for drift in instrument clock

Description

Correct for drift in instrument clock

Usage

undrift.time(x, slow.end=0, tname="t")

Arguments

x

an object of class "oce".

slow.end

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

name of time column.

Value

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

Details

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 x$data. The data length is altered in this process, e.g. a slow instrument clock (positive slow.end) takes too few samples in a given time interval, so undrift.time will increase the number of data.

Examples

library(oce)
rbr011855 <- read.oce("rbr011855")
d <- subset(rbr011855, t < as.POSIXct("2008-06-25 10:05:00"))
x <- undrift.time(d, 1)	  # a slow instrument clock lost 1 second
summary(d)
summary(x)