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Map display / Background maps
5
Recording Data
5.1
Getting Started
118
Introduction
Since Hydromagic Survey version 6.0, sensor data isn't recorded directly to a sounding file, like it used
to be in for instance, version 5.2.
All sensor data is now time tagged with millisecond accuracy and stored into a plain ASCII text file.
Advantages of using raw data files
Time Tagging
In a sounding, position values are combined with depth measurements and eventually motion and tide
correction data.
Because data isn't arriving at exactly the same time, the offset between a depth and position reading has
to be calculated.
This is done when generating a corrected sounding file from a raw data file using the "Generate Sounding
Wizard".
Latency
In hydrography, latency is the time elapsed between sending out a ping by the echosounder, and the
time the serial data with the depth value is received at the computer's serial port.
When this value is known (usually between 10 and 100 milliseconds), the delay is subtracted from the
recorded timestamp to get an even better accuracy.
The higher the speed of the vessel during a recording, the bigger the error because of latency will be.
When you are not able to apply latency corrections, don't go to fast !
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