The Knudsen sub bottom profiler is capable of operating as a subbottom profiler (3.5 KHz) and a conventional single beam echo sounder at 12 KHz. It is possible to run both modes simultaneously. The computer gets heading info directly from the gyro. Heave correction is not currently applied. Position data comes directly from a GPS receiver. During normal operation on the Healy, the 12 KHz mode is not used as it interferes with operation of the swath mapping (multibeam) system.