Quality Analysis Steps

 

This section documents the processing steps available in the Quality Analysis category.

 

The types of quality analysis currently available are:

 

 

 

Amplitude Analysis

 

Usage:

The Amplitude Analysis step performs single- or multi-channel- or single-channel average analysis of sample amplitudes and updates a user specified trace header with the results of the analysis.  Attribute types include RMS amplitude, Average magnitude, Maximum amplitude, Energy, Median magnitude, and Maximum magnitude. Results may be output to a report file.

 

Input Links:

1) Seismic data in any order (mandatory).

 

Output Links:

1) Seismic data in any order (mandatory).

 

Reference:

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Example Flowchart:

 

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Analysis type: Specify whether the amplitude analysis will be single-channel, multi-channel or single-channel average.  Single-channel attributes are calculated per trace.  Multi-channel attributes are calculated from the ensemble of traces in an input gather.

 

Single-channel — Select single-channel amplitude analysis.

 

Multi-channel — Select multi-channel amplitude analysis.

 

Attribute type: Specify the type of amplitude attribute.

 

RMS amplitude — If selected, calculate the root-mean-squared value in the analysis window.

 

Average magnitude — If selected, calculate the average of the absolute values in the analysis window.

 

Maximum amplitude — If selected, determine the maximum of the absolute values in the analysis window.

 

Energy — If selected, calculate the sum of the squares of sample values in the analysis window.

 

Median magnitude — If selected, determine the median value in the analysis window.

 

Maximum magnitude — If selected, determine the maximum value in the analysis window.

 

Time-space window: Specify the number of analysis windows per trace for a single- or multi-channel analysis.

 

Window — Specify the number of windows to use.

 

1 — The first window is checked by default for use in the calculations.

 

2 — Check to use a second window in the calculations.

 

3 — Check to use a third window in the calculations.

 

Start time (ms) — Enter the start time in milliseconds for the window to use.

 

Length (ms) — Enter the length in milliseconds for the window to use.

 

Apply LMO — Specify whether a linear moveout will be applied to the start time of the analysis window.

 

Apply — If checked, a linear moveout will be applied to the start time of the analysis window.

 

Velocity value — If linear moveout is to be applied, enter the moveout velocity.

 

Limit offset — If offset is to be limited, specify minimum and maximum values. Absolute values may be specified.

 

Limit — If checked, the offset will be limited, specify minimum and maximum values.

 

Minimum — Enter minimum offset value.

 

Maximum — Enter maximum offset value.

 

Absolute — Specify if absolute value is desired.

 

Yes — If checked, an absolute value will be used.

 

Output trace header — Select the trace header for each window that will be updated with the results of the analysis.

 

Report file — Specify whether to save results to a report file and browse to locate or create an amplitude analysis report file.

 

Output results to a report file — If checked, results will be saved to a report file.

 

Amplitude Spectrum

 

Usage:

The Amplitude Spectrum step inputs seismic data and outputs the amplitude spectrum of each trace into the output seismic file.

 

Input Links:

1) Seismic data in any order (mandatory).

 

Output Links:

1) Seismic data amplitude spectrum attribute traces (mandatory).

 

Reference:

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Example Flowchart:

 

 

Step Parameter Dialog:

 

 

 

 

Parameter Description:

 

Trace window: Specify the parameters related with the

 

Specify trace window — If checked, the specified trace window will be used for calculating the amplitude spectrum.

 

Start time (ms) — Enter the start time of the trace window to use in milliseconds.

 

Length (ms) — Enter the length of the trace window to use in milliseconds.

 

Apply LMO to window start time — If checked, a linear moveout will be applied to the start time of the trace window.

 

Linear moveout velocity — If linear moveout is to be applied, specify the moveout velocity.

 

Amplitude scale: Specficy the amplitude scale of the spectra either amplitude or dB.

 

Amplitude scale — Select the amplitude scale in dB down or in absolute amplitude.

 

dB scale control — Control the dB scale by specifying a zero decibel value.

 

Use this value as the 0 dB vlaue — If checked, the value entered will be used to control the dB scale.

 

Zero dB amplitude — Specify the zero decibel amplitude.

 

e+ — Enter the exponent (the number of tens) desired for multiplying the zero decibel value.

 

Spectrum averaging — Specify the number of spectra to be average based on the trace number.

 

Average spectra — If checked, the spectrums of the specified traces will be averaged.

 

First trace — Enter the first trace number in the window to be averaged.

 

Number of traces — Enter the number of traces to averaged.

 

Autocorrelation

Usage:

The Autocorrelation step computes a single trace autocorrelation for each input data trace.  The autocorrelation trace will have the same length as the input trace, and the zero lag value can be shift in time if you want to view both positive and negative lags.

 

Input Links:

1) Seismic data in any sort order (mandatory).

 

Output Links:

1) Seismic data in any sort order (mandatory).

 

Reference:

-

 

Example Flowchart:

 

 

Step Parameter Dialog:

 

 

 

Parameter Description:

 

Autocorrelation window start (ms) — Enter the start time in milliseconds for computing the trace autocorrelation.

 

Autocorrelation window length (ms) — Enter the length in milliseconds for computing the trace autocorrelation.  The autocorrelation function will be generated from data samples between the start time and the start time + window length.

 

Apply LMO to autocorrelation window start time — If checked, the autocorrelation window start time will be a function of offset: Start time = (source-receiver offset/ velocity) + Autocorrelation window start time.

 

Linear moveout velocity — Enter the linear moveout velocity.

 

Dead Trace Analysis

Usage:

The Dead Trace Analysis step allows to kill traces based on a user-defined trace header key word, and receiver lines or entire records based on the number and the relative location of dead traces.

 

Input Links:

1) Seismic data in any sort order (mandatory).

 

Output Links:

1) Seismic data in any sort order (mandatory).

 

Reference:

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Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Kill traces based on header values — If checked, traces will be killed based on the value stored on a user-defined trace header key word. Traces can be killed after some mathematical operations are performed with the selected traces header key word.

 

Kill receiver lines based on adjacent dead trace limit — If checked, receiver lines will be killed depending on a limit of consecutive dead traces.

 

Receiver line adjacent dead trace limit — Enter the minimum number of consecutive dead traces a receiver line must have to be killed.

 

Kill receiver lines based on percent of dead trace per line — If checked, receiver lines will be killed depending on the percentage of dead traces.

 

Dead trace limit per receiver line (%) — Enter the minimum percentage of deade traces a receiver line must have to be killed.

 

Kill entire records based on number of dead receiver lines — If checked, records are killed depending on the number of dead receiver lines.

               

Dead receiver line limit per record (%) — Enter the minimum percentage of dead receiver lines a record must have to be killed.

 

Kill entire records based on number of adjacent traces — If checked, records are killed depending on a limit of consecutive dead traces.

 

Adjacent dead trace limit — Enter the minimum number of consecutive dead traces a record must have to be killed.

 

Kill entire records based on percent of dead traces per record — If checked, records are killed depending on the percentage of dead traces per record.

 

Dead trace limit per record (%) — Enter the minimum percentage of dead traces a record must have to be killed.

 

Frequency Analysis

 

Usage: The Frequency Analysis step computes frequency related seismic attributes in distinct time windows from an input seismic file. Seismic attributes may be compute from single or multi-channel. Avaialble seismic attribeutes are dominant frequency, center frequency, average frequency, RMS frequency, bandwith or peak amplitude. Computed attributes can be stored in

 

Input Links:

1) Seismic data in any sort order (mandatory).

 

Output Links:

1) Seismic data in any sort order (mandatory).

 

Reference:

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Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Analysis Type: Specify if the analysis is to be performed in single- or multi-channel.

 

Single-channel — If selected, frequency analysis attribute will be computed on each single-channel of the current record.

 

Multi-channel — If selected, frequency analysis attribute will be computed on all the traces of the current record.

 

Single-channel average — Not yet available.

 

Attribute type: Specify the type of frequency attribute to be computed for the analysis.

 

Dominant frequency — If selected, computes the dominant frequency of the signal.

 

Center frequency — If selected, computes the center frequency of the signal.

 

Bandwidth — If selected, computes the bandwidth the signal.

 

Average frequency — If selected, computes the average frequency of the signal.

 

RMS frequency — If selected, computes the root mean square frequency of the signal.

 

Peak Amplitude — If selected, computes the peak amplitude of the signal.

 

Time space window: Specify the spatial/time extent where the calculation of the frequency attribute will be computed.

 

Window — Check how many windows will be used for the analysis. A maximum of three windows can be used.

 

Start (ms) — Enter the start time (upper boundary) in milliseconds where the calculation will be done.

 

Length (ms) — Enter the length of the time window in milliseconds where the calculation will be done.

 

Apply LMO — If checked a linear moveout (LMO) will be applied to the data before computing the analysis

 

Velocity value — Enter the velocity value to be used for the LMO correction.

 

Limit offset — If checked limit the selection of traces based on the offset.

 

Minimum — Enter the minimum offset where the calculation will be done.

 

Maximum — Enter the maximum offset where the calculation will be done.

 

Absolute — If checked uses the absolute value of the offset defined.

 

Output trace header — Select the trace header key word where the attribute calculation will be stored.

 

Signal to Noise

Usage:

The Signal to Noise step provides a statistical estimate of the signal to noise ratio of the selected seismic data. The results of the process are output into a user-defined trace header key word.

 

Input Links:

1) Seismic data in any sort order (mandatory).

 

Output Links:

1) Seismic data in any sort order (mandatory).

 

Reference:

Hatton, L., Worthington, M.H. and Makin, J. 1986, Seismic Data Processing, Theory and Practice.

 

 Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

Window start time (ms) — Enter the starting time of the analysis window on the trace data.

 

Window length in samples — Enter the length of the analysis window in samples.

 

Output Header — Select the trace header field to store the results of the signal to noise calculation.

 

Signal to Noise Attribute

 

Usage:

The Signal to Noise Attribute step provides a statistical estimate of the signal to noise ratio of the selected seismic data based on different metrics (average power, average RMS and average absolute) considering user-defined distinct signal and noise windows within the seismic data. The results of the process are output to user defined trace header locations and records can be automatically flagged depending on the computed attribute value.

 

Input Links:

1) Seismic data in any sort order (mandatory).

2) Seismic data in any sort order corresponding to a noise record (optional).

 

Output Links:

1) Seismic data in any sort order (mandatory).

 

Reference:

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Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Parameterization method: Specify the space/time extent of signal and noise windows.

 

Specify windows — If selected, specify signal and noise windows manually by defining start and end time interval and minimum and maximum channel group considered for the calculation. These windows will be fixed for all the records in the input seismic file.

 

Signal window start time (ms) — Enter the signal window start time (upper boundary) in milliseconds.

 

Signal window end time (ms) — Enter the signal window end time (lower boundary) in milliseconds.

 

Signal window minimum channel group — Enter the minimum channel to be considered in the signal window.

 

Signal window maximum channel group — Enter the maximum channel to be considered in the signal window.

 

Noise window start time (ms) — Enter the noise window start time (upper boundary) in milliseconds.

 

Noise window end time (ms) — Enter the noise window end time (lower boundary) in milliseconds.

 

Noise window minimum channel group — Enter the minimum channel to be considered in the noise window.

 

Noise window maximum channel group — Enter the maximum channel to be considered in the noise window.

 

Use auxiliary noise record — If selected, the noise window is computed from an auxiliary seismic file containing a single noise record. Signal window is defined manually and fixed for all input records.

 

Signal window start time (ms) — Enter the signal window start time (upper boundary) in milliseconds.

 

Signal window end time (ms) — Enter the signal window end time (lower boundary) in milliseconds.

 

Signal window minimum channel group — Enter the minimum channel to be considered in the signal window.

 

Signal window maximum channel group — Enter the maximum channel to be considered in the signal window.

 

Compare S/N ratio in the frequency domain — If selected, the signal-to-noise ratio is estimated from the overlap between the amplitude spectra of signal and noise windows.

               

% of overlapping area — Enter the percentage of overlapping area of frequency spectra where the estimate is going to be computed.

 

Minimum frequency (Hz) — Enter the minimum frequency in hertz of the spectra to be considered for the estimate.

 

Maximum frequency (Hz) — Enter the maximum frequency in hertz of the spectra to be considered for the estimate.

 

Signal window start time (ms) — Enter the signal window start time (upper boundary) in milliseconds.

 

Signal window end time (ms) — Enter the signal window end time (lower boundary) in milliseconds.

 

Signal window minimum channel group — Enter the minimum channel to be considered in the signal window.

 

Signal window maximum channel group — Enter the maximum channel to be considered in the signal window.

 

Noise window start time (ms) — Enter the noise window start time (upper boundary) in milliseconds.

 

Noise window end time (ms) — Enter the noise window end time (lower boundary) in milliseconds.

 

Specify velocity — If selected, signal and noise windows are defined based on a reference velocity varying linearly with the offset.

 

Reference velocity — Enter a reference velocity fo be used to define the location of the start time of the signal and noise windows.

 

Signal window start time below velocity (ms) — Enter the start time in milliseconds below the initial time computed from the reference velocity

 

Signal window length (ms) — Enter the signal window length in milliseconds

 

Signal window minimum channel group — Enter the minimum channel to be considered in the signal window.

 

Signal window maximum channel group — Enter the maximum channel to be considered in the signal window.

 

Noise window start time below velocity (ms) — Enter the start time in milliseconds below the initial time computed from the reference velocity

 

Noise window length (ms) — Enter the signal window length in milliseconds

 

Noise window minimum channel group — Enter the minimum channel to be considered in the noise window.

 

Noise window maximum channel group — Enter the maximum channel to be considered in the noise window.

 

Calculation method: Specify how if the signal to noise ratio is computed either on a record or trace-by-trace basis.

 

Record basis — If selected, estimate is based on the current record as a whole.

 

Trace by trace — If selected, the estimate is based on a trace-by-trace calculation.

 

Change noise window at each record — If checked, the noise window changes at each record. If unchecked, noise window changes at each record.

 

Output headers: Specify the location of the trace header key words where the attribute will be stored.

 

Top mute length (ms) — Enter the length of the top mute to be applied to both windows.

 

Bottom mute length (ms) — Enter the length of the bottom mute to be applied to both windows.

 

Minimum S/N ratio — Enter the minimum signal-to-noise ratio for a record to be consired bad.

 

Output average power header — Select the trace header location where the signal-to-noise ratio computed using the average power will be stored.

 

Output average power flag — Select the trace header location where the record flag based on the signal-to-noise ratio computed using the average power will be stored.

 

Output average RMS header — Select the trace header location where the signal-to-noise ratio computed using the average RMS will be stored.

 

Output average RMS flag — Select the trace header location where the record flag based on the signal-to-noise ratio computed using the average RMS will be stored.

 

Output average absolute header — Select the trace header location where the signal-to-noise ratio computed using the average absolute will be stored.

 

Output average absolute flag — Select the trace header location where the record flag based on the signal-to-noise ratio computed using the average RMS will be stored

 

Report file — Specify whether to save results to a report file and browse to locate or create an amplitude analysis report file.

 

Append to existing file — If checked, append report to existing report file.

 

Source Energy Estimation

Usage:

The Source Energy Estimation step computes an estimate of the source energy-to-noise ratio based on an analysis of samples values prior to and following the arrival of first break energy.  A text file is output that contains, for each source location, an estimate of (1) the energy-to-noise ratio, (2) the average energy, and (3) the average noise

 

Input Links:

1.       Seismic data in source order (mandatory).

2.       An Early Mute card containing reference times to the start of analysis. Typically, these would be picked at the time of the first arrivals.  (mandatory).

 

Output Links:

1)      Seismic data in source order (mandatory).

 

References

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Example Flowchart:

 

 

 Step Parameter Dialog:

 

 

Parameter Description:

Noise window specification: Specify the window for the analysis of noise.

 

Start Time above mute (ms) — Enter the time above the mute to start the analysis.

 

Window length (samples) — Enter the number of samples used to determine the noise estimate.

 

Data window specification: Specify the window for the analysis of noise.

 

Start Time above mute (ms) — Enter the time above the mute to start the analysis.

 

Window length (samples) — Enter the number of samples used to determine the signal estimate.

 

Offset window specification: Specify the window in terms of offset for the analysis of noise.

 

First offset window — Enter the first offset where the noise analysis will be done.

 

Last offset window — Enter the last offset where the noise analysis will be done.

 

Output Header — Indicate the trace header field to store the results of the source-energy estimate.

 

Report file: Specify file name path for the report.

 

Browse — Specify the name of the text file (*.txt) that will contain the results of the analysis.

 

Display report in separate window — If checked, report file is automatically shown in a separate window.

 

Spectral Comparison

Usage:

The Spectral Comparion step computes the spectral semblance between an input seismic and a reference seismic trace as selected from the input record on from an auxiliary seismic file with a pilot signature. The comparison against a pilot signature can be done based on a user-defined trace header location. Trace are flaged as bad or good depending on the value of semblance.

 

Input Links:

1)      Seismic data in source order (mandatory).

2)      An auxiliary seismic file with a signature can be used for the comparison (optional).

 

Output Links:

1)      Seismic data in source order (mandatory).

 

References

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Example Flowchart:

 

 

Step Parameter Dialog:

 

 

Parameter Description:

 

Signature comparison input: Specify the signature to be used for comparison

 

One signature per dataset from auxiliary seismic file — If selected, signature is defined by the first trace of the auxiliary pilot seismic file.

 

One signature per record from input data file — If selected, the signature is defined by the channel number of the input record from input seismic file.

 

                Input channel number — Enter the channel number to be used as signature.

 

Match signature based on trace header — If selected, signature is from and axiliary pilot file and matched against current record based on the value of a user-defined trace header locations.

 

Select header location for source number — Select the location of the header to be used as reference between signature and input seismic file.

 

Mean signature per record from input data file — If selected, signature is computed as the average of a user-defined range of traces.

 

Minimum channel number — Enter the minimum channel number to be used for the mean signature.

 

Maximum channel number — Enter the maximum channel number to be used for the mean signature.

 

Compare to average of prior traces in dataset — If selected, signature is defined as the average of the number of prioer traces defined in a rolling window.

 

Number of prior traces in rolling window — Enter the number of prior traces in a rolling window to be used for the average of the signature.

 

Calculate spectral semblance on receiver line basis — If selected, signature is defined as the average along a receiver line.

 

Start time for signature analysis (ms) — Enter the start time (upper boundary) in milliseconds of the time window for the signature analysis.

 

End time for signature analysis (ms) — Enter the end time (lower boundary) in milliseconds of the time window for the signature analysis.

 

Remove DC bias: Specify if a DC remove bias filter will be applied to the input seismic file before computing the spectral semblance.

 

Use remove DC bias filter — If checked applies a Remove DC bias step to the input seismic file. The filter is not store in the output seismic file, it is only applied before the calculations of the spectral semblance.

 

DC calculation method: select the method to estimate the DC bias.

 

Mean — If selected, estimates the DC bias as the mean of the seismic samples considered.

 

Median — If selected, estimates the DC bias as the median of the seismic samples considered.

 

(Min+Max)/2 — If selected, estimates the DC bias as central value between the min and max of the seismic samples considered.

 

Channel Average: DC bias may be estimated using a moving window running through channels in order to increase the reliability of the estimate.

 

Use running average across channels — If checked the DC bias is estimate taking into account a moving window computed across channels.

 

Number of channels to average — Enter the number of channels that belong to the moving window.

 

Gather Average: DC bias may be estimated using a moving window running through gathers (or records) in order to increase the reliability of the estimate.

 

Use running average across prior gathers — If checked the DC bias is estimate taking into account a moving window computed across prior gathers.

 

Number of gathers to average — Enter the number of gathers that belong to the moving window.

 

DC calculation window: define the time gate where the calculation is going to be computed.

 

Calculate DC in a window — If checked, only the entered window of each trace will be used to calculate the DC.

 

Start time (ms) — Enter the start time of the window to be used for calculating the DC value.

 

End time (ms) — Enter the end time of the window to be used for calculating the DC value.

 

Filtering:

 

Apply low-cut filter — If checked applies to the input seismic file a zero-phase Butterworth filter to the input seismic data before computing the spectral semblance. The filter is only applied to the input file and not store in the output seismic file.

 

Low-cut filtering: Specify low-cut filter parameters.

 

Apply low-cut filter — If checked, a low-cut filter will be applied to your data.

 

Low-cut corner frequency (Hz) — Enter the low half-power frequency in Hertz to be applied to your data.  The amplitude of this frequency will be reduced by a factor of two relative to the input.

 

Low-cut rolloff rate (dB/oct) — Enter the low rolloff filter slope in decibels per octave to be applied to your data. Higher numbers give steeper rolloff.

 

High-cut filtering: Specify high-cut filter parameters.

 

Apply high-cut filter — If checked, a high-cut filter will be applied to your data.

 

High-cut corner frequency (Hz) — Enter the high half-power frequency in Hertz to be applied to your data.  The amplitude of this frequency will be reduced by a factor of two relative to the input.

 

High-cut rolloff rate (dB/oct) — Enter the high rolloff filter slope in decibels per octave to be applied to your data. Higher numbers give steeper rolloff.

                                                                                                                                  

Attribute: Specify the trace header location where the spectral semblance and flags will be stored.

 

Select output header location for spectral semblance — Select the trace header location where the value of spectral semblance will be store.

 

Select output header location for quality flag — Select the trace header location where the flag of good or bad trace will be stored.

 

Scale spectra at reference dB level — If checked, spectra of inut and signature are scaled at a refecence level.

 

Spectral semblance cutoff (percent) — Enter the semblance cutoff value in percentage to distinguish between good and bad traces.

 

Start time for analysis (ms) — Enter the start time (upper boundary) in milliseconds of the time window for the analysis of the input seismic file.

 

End time for analysis (ms) — Enter the end time (lower boundary) in milliseconds of the time window for the analysis of the input seismic file.

 

Report file: Specifies if a report file is generated

 

Output Report file — If checked, outputs a report file with a unique name idenfier.

 

Audio alarm: Specifies alarm depending on the number of traces flagged as bad traces.

 

                Percent (%) limit of failed traces — Enter the percent of failed traces to trigger the alarm

               

                Alarm volume — Use slider to define the alarm volume

 

                Alarm browse — Select an audio file to be used as alarm.

 

Trace Analysis Report

Usage:

The Trace Analysis Report creates a text file that contains list bad records, and optionally, a list of traces that were killed in the geometry application step.

 

Input Links:

1)      Seismic data in any sort order (mandatory).

 

Output Links:

1)      Seismic data in source order (mandatory).

 

References

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 Step Parameter Dialog:

 

 

Parameter Description:

 

Report traces killed by Geometry Definition step — If checked, traces killed by a previous Geometry Definition step will be reported.

 

Report traces killed by processing steps — If checked, report traces killed by processing steps.

Use Geometry Definition dead traces in analysis — If cheked, dead traces from Geometry Definition will be included in the analysis.

 

Report bad records based on adjacent dead traces — If checked, bad records are to be identified according to the number of adjacent dead traces.

 

        Adjacent dead trace limit — Enter the number of adjacent dead traces that will cause the record the be considered “bad”, and therefore listed in the trace analysis report.

 

Report bad records based on number of dead traces per record — If checked, bad records are to be identified according to the number of adjacent dead traces.

 

        Dead trace limit per record — Enter the maximum percentage of dead traces that will cause the record the be considered “bad”, and therefore listed in the trace analysis report.

 

Report records killed by prior process — If checked, traces killed by previous steps, e.g. by geometry definition, will be included in the report.

 

Kill bad records — If checked, bad records are killed from the input seismic file.

 

Audio alarm: Specifies alarm depending on the number of traces flagged as bad traces.

 

                Percent (%) limit of failed traces — Enter the percent of failed traces to trigger the alarm

               

                Alarm volume — Use slider to define the alarm volume