Zero-Time Correction
Definition
A GPR processing step that aligns all traces to a consistent time-zero at the ground surface, removing the slight variation in the start time of traces caused by electronics delays and coupling differences. It is the first processing step applied before depth conversion.
- Applies to
- GPR trace time-zero alignment
- Corrects for
- Electronics delay and coupling differences
- Processing order
- First step, before depth conversion
- Goal
- Consistent time-zero at the ground surface
Common questions
What happens to depth estimates if zero-time correction is skipped?+
Depth conversion relies on the travel time measured from time-zero, so an uncorrected offset in the trace start times shifts every subsequent depth calculation by the same error, which can misplace the estimated depth of a buried target such as a clandestine grave or concealed object.
Why does coupling between the antenna and the ground cause a variable delay?+
The antenna's electrical contact and proximity to the ground can vary slightly as it moves across uneven terrain or different surface materials, shifting when the signal actually enters the ground relative to when the system starts recording, which is the trace-to-trace variation zero-time correction removes.
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