Skip to contents

Frequency-dependent signal-to-noise ratio from integrated spectra

Source: R/GetIntegratedSNR.R
GetIntegratedSNR.Rd

This function calculates the signal-to-noise ratio (SNR) as a function of frequency, interpreted as the temporal resolution of a proxy record. This variant of the SNR is obtained from a signal and a noise spectrum which are each integrated across frequencies before taking their ratio.

Usage

GetIntegratedSNR(input, N = 1, f1 = 2, f2 = "max", limits = NULL)

Arguments

input

a list of the spectral objects (?spec.object) signal and noise, usually to be obtained from a call to SeparateSignalFromNoise.

N

integer; number of proxy records averaged. The default returns the SNR of a single proxy record. For a different number, the SNR is calculated for a "stack" averaged across N individual proxy records with the same signal and equivalent noise characteristics, assuming independent noise between the records.

f1

index of the signal (and noise) frequency axis to specify the lower integration limit from which to integrate the spectra; per default the lowest frequency of the spectral estimates is omitted.

f2

as f1 for the upper integration limit; defaults to use the maximum frequency of the given spectral estimates.

limits

numeric vector with a frequency range of the integration: this is an alternative way of specifying the integration limits and overrides the setting by f1 and f2. If not NULL it must be a length-2 vector with the lower integration limit as first and the upper integration limit as second element.

Value

the SNR spectrum as a spectral object.

Details

The function is an implementation of Eq. (6) in Münch and Laepple (2018). The integral in (6) is approximated by the cumulative sum of the integration arguments from f.int1 to f.int2, where f.int1 = f1 and f.int2 consecutively increases from f1 to f2.

References

Münch, T. and Laepple, T.: What climate signal is contained in decadal- to centennial-scale isotope variations from Antarctic ice cores? Clim. Past, 14, 2053–2070, https://doi.org/10.5194/cp-14-2053-2018, 2018.

See also

spec.object for the definition of a proxysnr spectral object.

Author

Thomas Münch