The weighting function has been designed to give the narrow beams for a given sidelobe level. In order to make the relative wide beams, such as 7 degrees, the system employ Gaussian weights. The current sound velocity at the transducer and the frequency configuration are also used as input to this calculation. The weight calculation is performed to meet the requested beam opening, for a vertical beam, at the frequency of the centre
beam of the fan (or the reference beam frequency). The value for the sound velocity at the transducer is controlled from the Transducer Face page in the Environmental dialog box.
When you create a beam mode on an off-line computer, select manual transducer sound speed source and enter a sound speed value
representative for the waters where the beam mode is intended to be used.