How is detection time corrected in VUE?

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I have log files from Vemco/Innovasea receivers which I would like to process (export to CSV) through VUE software (v2.7).

One of the options in VUE, under VRL File Editor, is to perform automatic time correction to the detection times. It's unclear to me what this time correction means exactly and how it is calculated.

Does this feature synchronize all of the receiver times to each other and/or to the PC time?

Can I use exported data that has been time corrected to then calculate tag positions directly?

acoustic-telemetry
1 Answers

According to the VUE manual, section 3.1 (p. 25), automatic time correction can help fix time drift in the receivers when the clock drifts are “highly linear”. This correction is done by calculating a simple linear regression, per receiver, based on PC time at initialization and at offload. This process can also be done manually by comparing the receivers’ respective time offsets in the logs' CSV files, under the CLOCK_REF headings (there should be one for INITIALIZATION and one for OFFLOAD).

Note that the type and the amount of drift can vary between receivers as well as over time, and thus the degree of usefulness of applying an automatic time correction. For example, sometimes synchronization will require polynomial correction to achieve adequate synchronization (see YAPS sync function, which performs this type of correction). Other times, receiver clocks will 'jump' ahead/behind several seconds/minutes, which requires a more complex approach to properly synchronize. You will have to check how well VUE's automatic time correction works with your detection data.

This process in Python or R can be useful for visualizing (and correcting) the time drift while you synchronize your detection data. In most cases, it probably won't hurt to use automatic time correction, which can then be followed with a more fine-tuned synchronization approach as needed.

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