R: Computes complex demodulates using multiple taper techniques

demod.dpss {multitaper} | R Documentation

## Computes complex demodulates using multiple taper techniques

### Description

Computes complex demodulate of a given series around a given central frequency using multiple taper techniques. Returns amplitude, phase, and complex demodulate.

### Usage

    demod.dpss(x,centreFreq,nw,blockLen,stepSize=1,wrapphase=TRUE,...)

### Arguments

`x` | Time series, required to be contiguous.
`centreFreq` | Frequency around which to demodulate.
`nw` | Parameter controlling time-bandwidth.
`blockLen` | Length of sub-block to use; demodulate is computed on each block in turn.
`stepSize` | This is a proposed option that sets the index step size between blocks. Currently this must be set to 1 and changes in step size have not been implemented.
`wrapphase` | If true, routine wraps phases around +/-360 degree boundaries.
`...` | Additional arguments. Currently only includes depreciated arguments

### References

Thomson, D.J. (1995). The Seasons, Global Temperature, and Precession. Science, Volume 268, pp. 59–68.

Bloomfield P. (2000). Fourier Analysis of Time Series. 2nd edition. Wiley New York, pp. 97–130.

### Examples

    data(CETmonthly)
    nJulOff <- 1175
    xd <- ts(CETmonthly[,"temp"],deltat=1/12)
    demodYr <- demod.dpss(xd,centreFreq=1,nw=3,blockLen=120,stepSize=1)
    phase <- demodYr$phase
    offsJul <- 3*360/365
    phaseAdj <- phase
    phaseAdj[1:nJulOff] <- phase[1:nJulOff] + offsJul
    yr <- (time(xd)+1658)[1:length(phase)]
    plot(yr, phaseAdj, type="l", lwd=2,
         ylab="Phase of the Year in Degrees",
         xlab="Gegorian calender date")
    lines((1:nJulOff)/12+1659, phase[1:nJulOff], col="red")
    fit <- lm( phaseAdj ~ yr)
    abline(fit, lty=2, col="blue")
    cat(paste("Precession Estimate: ",fit$coef[2]*60*60,digits=6," (arcseconds/yr)\n",sep=""))

[Package multitaper version 1.0-13 Index]