The purpose of this publication is to provide the descriptions, procedures and detailed parameter explanations required to allow for safe and efficient use of the ST90 system. The publication also provides you with a thorough understanding of the parameters and adjustments provided by the ST90 system.
Some echoes are weak while others are stronger. To compensate for this it is often necessary to adjust the sensitivity of the ST90 system. This adjustment is commonly referred to as gain.
When an acoustic pulse is sent through the water, it will gradually lose its energy. The greater the distance between the transducer and the target(s), the greater the loss of energy. TVG (Time Variable Gain) compensates for the loss of acoustic energy due to geometric spreading and absorption.
Some echoes are close, others are further away. It is often necessary to adjust the radius of the search area. On the ST90 system, this is referred to as range.
In some situations you may wish to expand the range in the sonar presentations. Use View Range to expand the range shown in the relevant views to any percentage of the original Range setting.
The effect of the Gain adjustment is minimized if you apply RCG (Reverberation Controlled Gain) and AGC (Automatic Gain Control). The Display Gain is applied at the end of the filter sequence in the ST90 system. This means that you can use Display Gain if you are not completely satisfied with the results of the automatic gain functionality.
In order to detect fish or schools in the water column you may need to change the angle of the sonar beams. The transmitted sonar beams can be tilted electronically.
The Horizontal view presents the 360 degrees area around your vessel from a bird’s eye view. For the other views you must define the horizontal direction of the beam. Use Bearing to adjust the horizontal angle referenced to the vessel heading. You can also select the bearing line and drag it sideways.
The technical specifications summarize the main functional and operational characteristics of the ST90 system. They also provide information related to power requirements, physical properties and environmental conditions.
The ST90 system can send and receive information to and from several different peripherals. All transmissions take place as datagrams with data sentences. Each datagram has a defined format and length.
