The instrument arm was newly developed for the CRIS at our laboratory. The umbilical consists of two cables for the instrumentation's supply and datalink, a control cable for the adjustable arm, a hose for supplying an underwater sampling pump with air. The USTM . The USTM is a sophisticated instrument, capable of measuring the sedimentconcentration and the velocity of the sediment in the X-Y plane. The velocity is derived from the doppler frequency shift of the reflected acoustic sound.
Sediment concentration is derived from the amplitude of the reflected signal.
One USTM sensor consists of a single acoustic source with a 4.5 Mhz operating frequency. Two receivers pick up the reflected signals. The data from the USTM is directly sent to computers on the WESP at a 2Hz rate. One computer continuously stores all the incoming data to harddisk. A second laptop gives an on-line representation of the USTM signals.