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Analog sidescan (and sub-bottom) sonars produce one or more channels of voltage signal, usually in the domain of 0 - 5 Volts, -5 to +5 volts, or 0 to 10 volts for each data channel (port or starboard sidescan), plus a trigger signal to indicate start of line. GeoDAS uses the trigger signal (and in some cases also supplies it) to detect the start of each "ping", and digitizes the continuous analog channels at 16 bits resolution, at rates selected by the user, to create the digital data we log and display for each ping.
Some analog sonars offer a control API, allowing GeoDAS to provide a set of controls for the sonar, to adjust range, gain, etc. Other systems offer data only, and the user must use the manual controls on the sonar deck unit to adjust range and other tunable properties. With the latter systems, GeoDAS must detect the range from the period between the pings.
OIC supports analog data acquisition using National Instruments A2D cards, such as the PCI card 6023E, |
