Checking for unserviceable transducer elements by means of the Reception test on the Transducer page

The purpose of the Diagnostics dialog box is to allow on-line testing and verification of the hardware components in the ST90 system. Use the Transducer page to do a reception test to check the individual transducer elements. Any errors are then easily detected.

  • The ST90 system is turned on.
  • The ST90 system does not transmit ("ping").
  • The transducer is retracted to its upper position.
  • The vessel is berthed or at sea.
CAUTION:

You must never set the ST90 system to ping unless the transducer is submerged in water. The transducer can be damaged if it transmits in the open air.

For the best possible conditions, the ship must be "silent".

  • The water must be as deep as possible. Recommended minimum depth is 100 metres.
  • There must be no other vessels in the vicinity.
  • The vessel must lie still in the water.
  • As much machinery as possible must be turned off. It is particularly important to turn off electrical motors, as well as cooling systems and hydraulic pumps that may cause electric noise.
  • To prevent interference, all other hydroacoustic instruments must be turned off.

By means of the Diagnostics functionality, you can easily determine if the hardware components in the ST90 system are operational. And most important, you can make sure that all the transceivers channels and transducer elements are functional. Each button provides a small colour coded indicator.

  • No indicator: Status is OK. No actions are necessary.
  • Yellow: This is a warning. A closer investigation is recommended.
  • Red: This is an alarm. A closer investigation is required.
  • Blue: A device monitored by the diagnostic system is disabled.
  • Grey: No information is available.

The Diagnostics dialog box and functionality is only provided for performance monitoring. The functionality offered by the dialog box is not required for normal use of the ST90 system. The dialog box does not permit you to change any operational settings.

Procedure

  1. Make sure that you have sufficient water depth below the keel before you lower the transducer.
  2. Lower the transducer to its bottom position.
  3. Select the default settings.
    1. On the Main menu, select User Settings.
    2. Observe the Factory Settings list.
    3. Select the setting you want to use.
    4. Select Activate Selected Setting.
    5. Select OK to apply your changes and close the User Settings dialog box.
  4. Make the following preparations.
    1. On the Main menu: Set Range to 1500 m.
    2. On the Operation menu: Set Tx Power to Off.
    3. On the Active menu:
      1. Set Pulse Type to CW Medium.
      2. Set Frequency to the start frequency: 14 kHz
      3. Set Vertical TX Sector to Narrow.
      4. Set Noise Filter to Off.
      5. Set the Bottom Filter Threshold to Off.
    4. On the Setup menu: Select Diagnostics to open the dialog box.
  5. Select Transceiver to open the page.

    The Transceiver page provides a graphic presentation of the transceiver boards. The visual presentation reflects the physical location of the boards in the Transceiver Unit. Only static information is provided. The Board Information parameters offer key information about the supply power to the selected transceiver board, as well as the environmental conditions.

    Note:

    The Diagnostics dialog box and functionality is only provided for performance monitoring. The functionality offered by the dialog box is not required for normal use of the ST90 system. The dialog box does not permit you to change any operational settings.

  6. Make sure that all the transceiver boards are fully functional.
  7. Select Transducer to open the page.

    The Transducer page presents all the elements that are used in the transducer. The presentation attempts to organize the elements in the same manner as in the physical transducer. The transceiver boards are shown as "buttons". Select a transceiver board to highlight the elements that are physically connected to the board.

  8. Select Reception Test to start an automatic test of the individual transducer elements.

    For the reception test to start, the ST90 system must be transmitting (pinging). The reception test validates each element in the transducer.The test returns the results using colour codes.

    • Green: The transducer element is fully operational.
    • Red: The transducer element offers reduced performance.
    • Black: The transducer element is not working ("dead").

    For more information, observe the tooltip provided for each element rectangle.

  9. Make sure that the number of unserviceable ("dead") elements does not degrade the performance of the ST90 system.

    A small number of unserviceable transducer elements are accepted, even for operational use. This is regarded as "graceful degradation�. The ST90 system offers a large number of transceiver channels. 12 identical transceiver boards are used. If a single channel fails during normal operation, you are not likely to detect it. Even if several channels fail, you may not see it.

    The detection of a faulty channel depends on the physical location of the relevant transducer element. If faulty channels are grouped together on the transducer face, this may cause a visible defect in the display presentation. If they are scattered, the visible defect may be a lot harder to see. In all cases, the echoes from the neighbouring channels cause an interpolation that will restore a lot of the degraded presentation.

    Which actions to take if single channels fail depend on the operational impact, the overall performance of the ST90 system, and a cost/benefit assessment. The most important factor in the cost/benefit assessment is whether you need to replace the transducer, or just a single transceiver board. If more than 3% of your transducer elements have failed, we recommend that you contact your dealer for advice.

    Note:

    For further investigations of this issue, use the functionality offered by the Element BITE (Element Built In Test Equipment) dialog box.

  10. If the result from the reception test shows a number of transducer elements that are either defective or offer reduced performance, repeat the test.

    With the vessel in port, the environmental conditions are not satisfactory. In the shallow waters of the port, noise from other vessels, dockyard workers or machinery will cause unreliable test results. If you do this tests in a busy harbour, or with noise sources present, the sensitive receivers will detect all the noise in the nearby waters. Excessive noise or interference may be misinterpreted as physical defects.

    You may need to repeat the test several times, and - if necessary - implement a "silent ship" to improve the conditions.

  11. Finish the test.
    1. Close the Diagnostics dialog box.
    2. Set Tx Power to Off.
    3. Hoist the transducer back up to its upper position.
RequirementsResult
The maximum number of bad elements is: 3 

If the noise level is higher than specified, you must investigate why.

  • Make sure that the Transceiver Unit is adequately grounded.
  • Make sure that other electric equipment and machinery on board, such as cooling systems, hydraulic pumps, electric motors, etc, do not influence the noise reading. To reduce noise, turn off as much machinery as possible, especially electrical motors.
  • Make sure there is no interference from other hydroacoustic systems.
  • Make sure there is no environmental noise, for example, from other vessels in the vicinity or animal life.