bandpass {astrochron} | R Documentation |

## Bandpass filter stratigraphic series

### Description

Bandpass filter stratigraphic series using rectangular, Gaussian or tapered cosine (a.k.a. Tukey) window. This function can also be used to notch fiter a record (see examples).

### Usage

```
bandpass(dat,padfac=2,flow=NULL,fhigh=NULL,win=0,alpha=3,p=0.25,demean=T,
detrend=F,addmean=T,output=1,xmin=0,xmax=Nyq,genplot=T,verbose=T)
```

### Arguments

`dat` |
Stratigraphic series for bandpass filtering. First column should be location (e.g., depth), second column should be data value. |

`padfac` |
Pad with zeros to (padfac*npts) points, where npts is the original number of data points. |

`flow` |
Lowest frequency to bandpass. |

`fhigh` |
Highest frequency to bandpass. |

`win` |
Window type for bandpass filter: 0 = rectangular , 1= Gaussian, 2= Cosine-tapered window (a.k.a. Tukey window). |

`alpha` |
Gaussian window parameter: alpha is 1/stdev, a measure of the width of the Dirichlet kernel. Choose alpha >= 2.5. |

`p` |
Cosine-tapered (Tukey) window parameter: p is the percent of the data series tapered (choose 0-1). |

`demean` |
Remove mean from data series? (T or F) |

`detrend` |
Remove linear trend from data series? (T or F) |

`addmean` |
Add mean value to bandpass result? (T or F) |

`output` |
Output: (1) filtered series, (2) bandpass filter window. |

`xmin` |
Smallest frequency for plotting. |

`xmax` |
Largest frequency for plotting. |

`genplot` |
Generate summary plots? (T or F) |

`verbose` |
Verbose output? (T or F) |

### Value

bandpassed stratigraphic series.

### See Also

`lowpass`

, `noKernel`

, `noLow`

, `prewhiteAR`

, `prewhiteAR1`

, and `taner`

### Examples

```
# generate example series with periods of 405 ka, 100 ka, 40ka, and 20 ka, plus noise
ex=cycles(freqs=c(1/405,1/100,1/40,1/20),end=1000,dt=5,noisevar=.1)
# bandpass precession term using cosine-tapered window
bandpass_ex <- bandpass(ex,flow=0.045,fhigh=0.055,win=2,p=.4)
# notch filter (remove) obliquity term using cosine-tapered window
# if you'd like the final notch filtered record to be centered on the mean proxy
# value, set addmean=FALSE
notch_ex <- bandpass(ex,flow=0.02,fhigh=0.03,win=2,p=.4,addmean=FALSE)
notch_ex[2] <- ex[2]-notch_ex[2]
pl(2)
plot(ex,type="l",main="Eccentricity+Obliquity+Precession")
plot(notch_ex,type="l",main="Following application of obliquity notch filter")
```

*astrochron*version 1.3 Index]