StreamPro ADCP Operation Manual - global site

StreamPro ADCP Operation ManualSelf-Contained ADCP: An ADCP equipped with internal batteries and aninternal recorder for autonomous operation.Sentinel: The model name for a self-contained Workhorse ADCP.Ship Coordinates: Profile data is reported in an orthogonal coordinateframe as referenced to the ship (if beam 3 is forward then ship coordinatesare the same as instrument coordinates).Sidelobes: Peaks in sound intensity generated by a transducer found to theside of the main lobe.Sidelobe Contamination: This only need be considered when operating anADCP near a boundary (e.g. in shallow water). The beam angle of the mainlobe of an ADCP transducer is 20 or 30º off the vertical, which means thatthe distance to the boundary along the ADCP centerline is shorter than thedistance to the boundary along a beam. Because most boundaries will reflectvery strongly (much more strongly than the scatterers), sidelobe energycan travel the shorter path directly to the surface and thereby includethe “velocity” of the boundary with the velocity measurements taken alongthe beams at any longer distance. This potential for interference dependsstrictly on the beam angle. An ADCP with a 20º beam angle has the potentialfor sidelobe contamination at (distance to the boundary)*cos(20º), orequivalently, the last 6% of the profile. Note: Sidelobe contamination is notrelevant for DVLs, which specifically look for the bottom.Software Break: When using radio or acoustic telemetry, it is usually notpossible to send a break signal. Under these circumstances an ADCP can beconfigured to recognize a series of keystrokes (i.e. = = =) as a break.Source: Originator of sound of known frequency, here typically the transducerof an ADCP.StreamPro: Model name for ADCP designed for discharge measurement inshallow waterways.------ T ------Top Discharge: When using an ADCP to measure river discharge, it is notpossible to measure all the way to the surface (due to the blank zone and tothe need to mount the transducers at sufficient depth to remain submergedwith no air entraining past the transducers). In order to get an accurate approximationof the total discharge, the flow in this area must be estimatedand included, usually by extrapolating the measured velocities to the surface.Transducer: A device to convert electrical energy into sound waves, andvice versa.P/N 95B-6003-00 (February 2008) page 109