• Standard calibration of echo sounders and integrators with optimal copper spheres 

      Foote, Kenneth G.; Knudsen, Hans Petter; Vestnes, Gudmund (Fiskeridirektoratets skrifter, Serie Havundersøkelser, Research report, 1983)
      Calibration of fisheries echo sounders and integrators by means of optimal copper spheres is reviewed. The standard procedure is elaborated. Maintenance of O.1 dB precision is described for a wide range of temperatures ...