This process detects spikes, and performs actions on the affected traces and/or regions.
Create a Despike process
- In the Control Panel, open the Process tab.
- Click the blue "+" icon and select New Process.
- Search and double-click Despike.
- Type a name for the process and click OK.
Define Despike settings
- Volume: Select the input volume
Region: Select the region that the process is limited to
- Whole Trace - no limit applied
- Horizon/Constant - define a starting time or horizon and enter a window length
- Header - use a header to provide the starting time and enter a window length
Mode: choose the analysis method
- Peak Magnitude - if a value has magnitude greater than maximum, or less than minimum it is flagged as a spike
- RMS - if the RMS average of the samples is greater than the value, the window is flagged as a spike
- Average - if the average magnitude of the samples is greater than the value, the window is flagged as a spike
Vertical - compare local regions of a trace to a larger window of the trace using sliding windows
- Calculate the average of a small window
- Calculate the average of a long window, excluding the samples in the small window. This long window result is the reference
- If the short window result is greater than the “Compare factor” times the reference, then flag the short window as a spike
Horizontal - compare a trace to its neighbours, over a sliding window
- For each trace, calculate the average of the absolute values of the window
- If the result is greater than the “Compare factor” times its neighbours, then flag the short window as a spike
Action: Perform the following when spikes are detected
- Drop Traces - drop traces containing a spike, leaving NaNs or missing traces
- Mark Trace as Dead - keep traces, but set the TRID header to 30,000
- Set custom TRID - keep traces, but set the TRID header to a custom value
- Mute Spikes - ramp to zero - set spikes to 0 and smooth using the mute radius. Refer to the diagram - green curve
- Mute Spikes - clip to max values and smooth - set spike values to the Clip Magnitude, and smooth using the mute radius. Refer to the diagram - blue curve
Store max/average etc - Store spike values in a header
- The stored value depends on the detection algorithm used
- Where amplitude limits are used, the magnitude of the largest spike is stored
- For averages and rms, the resulting value is stored
- The value can be scaled or shifted before storing
- The despike result volume is available in the Volume tab