Navigation and Seamanship

3.1.8.4. Recorders

The recorders are responsible for displaying and recording of the echos in different forms like paper recorder, a flash-light display, an audible signal or an oscilloscope (Cathode Ray Tube ( CRT)) . Modern echosounders often use a colour monitors to show the echoes. In recent years , most advanced, light weight displays such as LCD and LED are used in echosounders, with that the crystal clear visibility of the display is possible even under the direct sunlight. The recording unit also has another important function of starting the transmitter to produce the electrical pulse and to measuring the time between the transmission of the sound pulse and the reception of the echo. Oscilloscope or Cathode Ray Tube (CRT) presentations of echo signals is sometimes known as fishlupe.

The colour display will clearly differentiate the echoes with varying strengths. This display is therefore the best for the detailed study and identification of echoes, while the CRT display is well suited to the recognition of fish echoes close to the bottom. This feature can further be improved with a bottom lock system . To achieve superior overall performance it was an obvious step to combine paper recording with CRT display and so conveniently utilize the advantages of both systems. Such units naturally belong to the more powerful and expensive class of echo sounders .