RoxAnn Hydrographic Features Applications Technical FAQ's   The RoxAnn GD-A Hydrographic system interfaces with the existing echosounder and GPS/DGPS onboard the survey vessel and data is displayed via the RoxMap software program on the survey PC, creating colour coded seabed material maps in 2 and 3 dimensions and in real-time. It is available for operation with echosounder frequencies from 15 kHz to 210kHz, either as a single or dual or four frequency system.