How to open
This page is opened either in the Beam Mode dialog box. The dialog box can be opened either from the Beam Mode Adm. function or View Beam Mode.
Opening the Beam Mode dialog box from the Beam Mode Adm. function enables you to edit and make changes to a chosen beam mode.
Beam Mode Adm. is located on the Setup menu. Select beam mode from the list, then select Edit to make changes to the beam mode.
Opening the Beam Mode dialog box from the View Beam Mode function allows you to view the current beam mode, but not making any changes.View Beam Mode is located on the Operation menu.
Description
The Beam Mode Administration dialog box allows you to create and delete beam modes for the ME70 system. By means of the Beam Mode dialog box you can also view and edit the beam modes.
Details
Upper Frequency
Select the upper frequency to be used by the beams in the fan.
Lower Frequency
Select the lower frequency to be used by the beams in the fan.
Freq(uency)/Beam Spacing
Select the frequency/beam spacing mode. For further information, refer to the Frequency distribution concept description.
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Linear This mode provides equidistant pacing in frequency of all the beams inside the selected band.
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Optimized This mode provides an optimized beam spacing.
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Manual Select this mode if manual overriding of frequency allocation through the XML file description of the beam mode will be used.
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Frequency/Space Distribution
Select the frequency/space distribution mode. The alternatives are:
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Inverse V This mode assign the highest frequencies to the centre beams of the fan.
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V-shape This mode assign the highest frequencies to the beams with the most athwart beam steering in the fan.
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Pulse Duration
The Pulse Duration setting specifies the current duration ("length") of the transmitted pulse. Select the pulse duration to be used for all the beams. The frequency band and the number of active beams will limit the bandwidth for each beam. This bandwidth will further limit the minimum pulse duration that you may select.
Pulse Type
The ME70 system offers several pulse types:
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LFM (Linear Frequency Modulation) |
Order Beam Tx By
Select one of the following alternatives:
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Beam Number Beam number 0, 1, 2 and 3 is sent in the first group followed by 4, 5, 6 and 7 etc.
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Increasing Steering Beams with the maximum athwart angle are transmitted first, followed by beams with decreasing steering.
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Decreasing Steering Beams located close to the vertical are transmitted first, followed by beams with increasing steering.
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# Beams in Group
Select the number of beams to be transmitted in each group. Valid choices are between 1 and 4. Using fewer beams in each group will increase the source level. The increase is displayed. By reducing the number of beams in each group the blind zone of the system is also increased. There can be maximum 23 groups.
Use the Tx Amplitude Plot to see the resulting transmit pulse.
Source Level Increase
When the number of beams in a beam group is reduced, this will have an effect on the source level. This parameter identifies this effect.
Fc Factor
The Fc Factor affects the number of Fourier coefficients used in the signal processing of the ME70. Using more Fourier coefficients (higher
Fc Factor) will decrease sidelobes in time/range, but will also increase the processing load and can potentially result in reduced
maximum ping rate.
We recommend that you to use as high Fc Factor as possible while meeting potential ping rate requirements. If your survey involves objects close to the bottom it is particular
recommended to use the maximum Fc Factor.
Default value is the maximum value 4 and it is not recommended to use a value lower than 1.5.
Edit
This opens the Beam Mode dialog box for the appropriate beam mode. The Beam Mode dialog box allows you to edit the beam mode’s current operational parameters. When editing a calibrated mode you must ensure the changes you have made are compatible with the calibration data stored with
the configuration.
Delete
Select this button to delete the highlighted beam mode. When deleting a beam mode you will receive a verification question if you really want to delete the beam mode. If the beam mode has been calibrated previously you will receive a second verification question on whether or not you want
to delete the beam mode.
New
This button creates a new beam mode. The Beam Mode dialog box is provided to enter the name of the new beam mode. The new beam mode will be created with a default configuration, and you must edit these parameters using the Edit button.