galileoQC.qualitycontrol.psdChannelDiff

Plot power spectral density of the difference between two channels.

Author: Mark Helm Dransfield

Created: ca 2023

License: CC BY-SA

Module Contents

Functions

psdChannelDiff	Plot the PSD (log-log Sqrt(Power) from welch method) of channel1 - channel2 in each flightLine.
psdChannel	Plot the PSD of channel averaged over the flightLines.
psdChannelGain	Plot the FFT of filchan / rawchan averaged over the flightLines.
_costaper	Return the gain vector corresponding to the freq vector for a cosine taper low-pass filter with centre frequency corresponding to nominalperiod and pass frequency 2/3rd the 50% pass frequency; cut frequency 4/3rds.
_period_to_dist	Converts period (sec) to distance by multiplying by the GLOBAL mean speed (m/s). For use in creating a secondary wavelength axis for psdChannelDiff.
_dist_to_period	Converts distance (metres) to period(sec) by dividing by the GLOBAL mean speed (m/s). For use in creating a secondary wavelength axis for psdChannelDiff.
_time_frequency	Returns the sample frequency of the data in the project group. Simply calculated as the inverse of the difference of the first two sample times in the first line. Relies on the TimeChannel attribute being set.
_mean_line_speed	Returns the mean line speed of the data in the line (which is in the given project group). Instantaneous speeds are calculated for each sample along the line and their average value returned. Relies on the XChaneel, YChannel and TimeChannel attributes being set.

Data

groupName

API

galileoQC.qualitycontrol.psdChannelDiff.groupName

None

galileoQC.qualitycontrol.psdChannelDiff.psdChannelDiff(whizzFile, channel1, channel2, flightLines=[])

Plot the PSD (log-log Sqrt(Power) from welch method) of channel1 - channel2 in each flightLine.

Parameters

whizzFile : String or pathlib Path

Name of a HDF5 Whizz file, including path and extension.

flightLines : String List, optional

A list of flightline, e.g. ['1000110.0']. Default is all lines in whizzFile.

channel1 : String

The name of a channel.

channel2 : String

The name of a channel.

Returns

None.

galileoQC.qualitycontrol.psdChannelDiff.psdChannel(whizzFile, channel, flightLines=[], shortestPeriod=0.0, minlinelenkm=None, verbose=False)

Plot the PSD of channel averaged over the flightLines.

Parameters

whizzFile : String or pathlib Path

Name of a HDF5 Whizz file, including path and extension.

channel : String

The name of the channel to be analysed.

flightLines : String List, optional

A list of flightline, e.g. ['1000110.0']. Default is all lines in whizzFile.

shortestPeriod : Float, optional

The left hand limit of the x (period) axis of the plot in seconds. Default is 0.0.

minlinelenkm : Float, optional

Flightlines shorter than this number of kilometres will be ignored in the calculation. Default is None.

verbose : Bool, optional

If True, more information is printed. Default is False.

Returns

None.

galileoQC.qualitycontrol.psdChannelDiff.psdChannelGain(whizzFile, rawchan, filchan, flightLines=[], nominalPeriod=0.0, shortestPeriod=0.0, minlinelenkm=None, verbose=False)

Plot the FFT of filchan / rawchan averaged over the flightLines.

Parameters

whizzFile : String or pathlib Path

Name of a HDF5 Whizz file, including path and extension.

rawchan : String

The name of the channel to be the denominator in the gain.

filchan : String

The name of the channel to be the numerator in the gain.

flightLines : String List, optional

A list of flightline, e.g. ['1000110.0']. Default is all lines in whizzFile.

nominalPeriod : Float, optional

At this period in seconds, a vertical red line is drawn. Default (0.0) is to not draw the line.

shortestPeriod : Float, optional

The left hand limit of the x (period) axis of the plot in seconds. Default is 0.0.

minlinelenkm : Float, optional

Flightlines shorter than this number of kilometres will be ignored in the calculation. Default is None.

verbose : Bool, optional

If True, more information is printed. Default is False.

Returns

None.

galileoQC.qualitycontrol.psdChannelDiff._costaper(freq, nominalPeriod)

Return the gain vector corresponding to the freq vector for a cosine taper low-pass filter with centre frequency corresponding to nominalperiod and pass frequency 2/3rd the 50% pass frequency; cut frequency 4/3rds.

galileoQC.qualitycontrol.psdChannelDiff._period_to_dist(p)

Converts period (sec) to distance by multiplying by the GLOBAL mean speed (m/s). For use in creating a secondary wavelength axis for psdChannelDiff.

Parameters

p : Float

The period in seconds.

Returns

Float. The distance in metres.

galileoQC.qualitycontrol.psdChannelDiff._dist_to_period(x)

Converts distance (metres) to period(sec) by dividing by the GLOBAL mean speed (m/s). For use in creating a secondary wavelength axis for psdChannelDiff.

Parameters

x : Float

The distance in metres.

Returns

Float. The period in seconds.

galileoQC.qualitycontrol.psdChannelDiff._time_frequency(group)

Returns the sample frequency of the data in the project group. Simply calculated as the inverse of the difference of the first two sample times in the first line. Relies on the TimeChannel attribute being set.

Parameters

group : HDF5 group

Must be the project group (top level of hierarchy in whizz File).

Returns

Float. The sample frequency in Hz.

galileoQC.qualitycontrol.psdChannelDiff._mean_line_speed(group, line)

Returns the mean line speed of the data in the line (which is in the given project group). Instantaneous speeds are calculated for each sample along the line and their average value returned. Relies on the XChaneel, YChannel and TimeChannel attributes being set.

Parameters

group : HDF5 group

Must be the project group (top level of hierarchy in whizz File).

line : String

The line identifier.

Returns

Float. The mean speed along the line.