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Functions and dialog boxes
Pages in the Environment dialog box
Environmental parameters such as salinity, sound speed and water temperature all play an important part to present accurate echo data. Use the Environment parameters to define these values. Depending on the current sea and weather conditions, you may need to change these values frequently.
Water Column page
To achieve correct echo information, the current environmental parameters must be known to the ST90 system. The Water Column page collects these parameters. These must be defined to match the current conditions.

About this manual
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.
Simrad ST90
Operating procedures
Maintenance procedures
User interface
Menu system
Functions and dialog boxes
- Main menu: functions and dialog boxes
  The Main menu is located at the top of the menu structure. It offers the most common functions for efficient use of the ST90 system. Unless you hide the entire menu system, the Main menu is visible at all times, even if you close the secondary menus.
- Operation menu: functions and dialog boxes
  The Operation menu allows you to control the operating mode, the recording functionality, and how the ST90 system transmits audio pulses ("ping") into the water.
- Display menu: functions and dialog boxes
  The Display menu provides basic functions related to the screen behaviour and presentation of the echo data. Use the Display menu to control the visual aspects of the system, and to show or hide various elements in the presentation.
- Setup menu: functions and dialog boxes
  The Setup menu provides basic functions related to the installation parameters and the communication with peripheral systems.
- Active menu: functions and dialog boxes
  The Active menu offers parameters related to current views and data presentations provided by the ST90 system.
- Secondary functions and dialog boxes
- Pages in the Output dialog box
  A key function of the ST90 system is its ability to export data. The purpose of the Output dialog box is to collect all functionality related to data output in one easily accessible location.
- Pages in the Display Options dialog box
  The Display Options dialog box is used to specify basic settings for the sonar presentation.
- Pages in the Environment dialog box
  Environmental parameters such as salinity, sound speed and water temperature all play an important part to present accurate echo data. Use the Environment parameters to define these values. Depending on the current sea and weather conditions, you may need to change these values frequently.
  - Water Column page
    To achieve correct echo information, the current environmental parameters must be known to the ST90 system. The Water Column page collects these parameters. These must be defined to match the current conditions.
- Pages in the Diagnostics dialog box
  The ST90 system is a computerized sonar. There are hardly any analogue circuitry, and the possibility of traditional troubleshooting is limited. In order to rectify this, a built-in software application is available to offer test and maintenance functionality. The Diagnostics dialog box controls the test and diagnose application that checks the performance of the ST90 system.
- Pages in the Installation dialog box
  Before you use the ST90 system you must set it up to communicate with the relevant peripherals. Use the Installation dialog box to set up all interfaces with external devices, and to set up basic parameters related to installation and operation. In most cases, you only need to do this once.
- Pages in the Echogram dialog box
  The Echogram dialog box allows you to control the echogram presentation in the Inspection views. Two pages control the horizontal lines and the echogram type with applied TVG (time variable gain). One page controls how fast the echogram travels horizontally across the presentation.
- Pages in the Information Pane Options dialog box
  The ST90 system offers several information panes to provide additional and detailed data from the presentations. The information panes are opened and closed from the top bar. Several of the information panes are fitted with a Setup button. Select Setup to open the Information Pane Options dialog box. Use the Information Pane Options dialog box to change the operating parameters for the data provided in the information panes.
Concept descriptions
Technical specifications
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.
Datagram formats
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.
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Water Column page

To achieve correct echo information, the current environmental parameters must be known to the ST90 system. The Water Column page collects these parameters. These must be defined to match the current conditions.

This page is opened from the Environment dialog box. The Environment dialog box is opened from the Setup menu.

Description

You must correctly set the sound speed through the water to obtain accurate depth readings and fish echoes. Several parameters are required to calculate the correct sound speed value. If these parameters are unknown, use the default value of 1494 m/s. This is a typical mean value for sound speed in salt water.

Details

Conditions

Use these settings to set up the ST90 system for operation in fresh or salt water.

Sound travels at different speeds in salt and fresh water. For this reason, the ST90 system must know your water profile. The default setting is Salt.

Parameters

Use these settings to provide manual values.

Freshwater/saltwater settings, temperature, salinity, acidity, depth, and operating frequency are all used to calculate absorption.

Temperature: Specify the water temperature. Once the salinity and temperature information is provided, the ST90 system calculates the sound speed and absorption.
Salinity: Provide the current salinity. Once the salinity and temperature information is provided, the ST90 system calculates the sound speed and absorption.

Sound Speed

You must correctly set the sound speed through the water to obtain accurate depth readings and fish echoes.

Calculated: Select Calculated to allow the ST90 to calculate the sound speed and absorption based on your supplied parameters (frequency, salinity, acidity sound speed, and water temperature).
Manual: Select Manual to provide a sound speed value manually. A value provided manually can be relevant if neither a sound speed sensor nor a CTD (Conductivity Temperature Depth) sensor is available.

Absorption

The absorption curve is calculated and drawn using the parameters provided.