1 M or m â prefix designating a number in thousands (not to be confused with SI prefix M for mega-or m for milli).
There are two types commonly referred to as: 'Shallow' and 'Deep' water. The differences are not only in the Frequency but also in the Beam Width and they are as follows: 'Shallow' water HST-WSBL 106-72 Transducer will operate on 2 frequencies on the HDS models: 200 (20Â°) & 83KHz (60Â°). 'Deep' water HST-DFSBL 106-77 Transducer will operate on 2 frequencies on the HDS models: 200KHz (12Â°) & 50KHz (35Â°).
High frequency (192 - 200 kHz) transducers come in either a narrow or wide cone angle. The wide cone angle should be used for most freshwater applications and the narrow cone angle should be used for all saltwater applications. Low frequency (50 kHz) sonar transducers are typically in the 30 to 45 degree range.