seasonder_findFORNullsInSpectrum {SeaSondeR} | R Documentation |
Identify Nulls in First Order Region (FOR) Spectrum
Description
This function locates the null points in the First Order Region (FOR) of a Doppler spectrum. These nulls define the boundaries separating the first-order Bragg peak from the surrounding noise or second-order energy.
Usage
seasonder_findFORNullsInSpectrum(
seasonder_cs_object,
spectrum,
doppler_bins,
negative_Bragg_region = FALSE
)
Arguments
seasonder_cs_object |
A |
spectrum |
A numeric vector representing the power spectrum to analyze. |
doppler_bins |
A numeric vector containing the Doppler bins corresponding to the spectrum. |
negative_Bragg_region |
A logical value indicating whether the function should analyze the negative Bragg region. Default is |
Details
The function executes the following steps:
-
Retrieve First Order Settings: The function extracts the
fdown
parameter, which defines the drop-off level relative to the maximum power. -
Prepare the Spectrum:
Convert all values to negative absolute magnitudes to facilitate peak detection.
Reverse the spectrum and Doppler bins if analyzing the negative Bragg region.
-
Find the Main Spectral Peak:
The function identifies the first major peak using
findpeaks
with at least two consecutive increases and decreases.The search is limited to the portion of the spectrum beyond this peak.
-
Determine the First Order Boundaries:
The maximum power (
MAXP
) is found along with its bin index (MAXP.bin
).A threshold value
start_point_P
is computed asMAXP / fdown
to establish the cutoff point for the null search.
-
Search for Nulls: The spectrum is split into left and right sections:
The right-side spectrum is analyzed using
seasonder_findFORNullsInFOR
to find the right null.The left-side spectrum undergoes the same process but reversed.
-
Output the Results: The function returns a list containing:
The sequence of Doppler bins defining the FOR region.
The maximum power detected (
MAXP
).The Doppler bin index where
MAXP
occurred (MAXP.bin
).
Value
A list with three elements:
-
FOR
: A sequence of Doppler bins defining the first order region. -
MAXP
: The maximum power found in the spectrum. -
MAXP.bin
: The Doppler bin index of the maximum power.
See Also
-
seasonder_findFORNullsInFOR
for detecting nulls within a selected region. -
findpeaks
for peak identification. -
seasonder_getFOR_parameters
for retrieving FOR settings.