Page 70 of 254
Part No. 96000001
5.6.1 Frequency (kHz) 170 kHz – 450 kHz
The Sonic MBES operates on a user-selectable frequency, from 170 kHz to 450 kHz (standard with
Type 1006 projectors; the Type 1004 projector is limited to 200 kHz to 400 kHz), in 10 kHz steps.
The operating frequency can be changed on the fly; there is no need to stop recording data, go
offline, or load any firmware. The operating frequency is selected via the drop-down menu next to
Frequency (kHz) or can be typed in (within the 170 kHz to 450 kHz restrictions).
Figure 58: Operating Frequency Selection
5.6.1.1 700 kHz UHR (Sonic 2024/2022)
The optional UHR upgrade enables the sonar to operate at 700 kHz for Ultra High Resolution. If this
option is installed, there will be the added 700 kHz frequency, after 450, in the available frequency
list (as seen above). If the upgrade is not installed, there will be no listing of this frequency.
The UHR upgrade requires a Type 1006 projector, which covers the normal 170 – 450 kHz frequency
range, but can also provide the necessary power to operate at 700 kHz. The projector is specially
labeled with a blue indicator at the end of the projector.
When 700 kHz is selected, the swath sector will automatically be reduced to 70°. The UHR upgrade
is intended for short-range operation. In the UHR mode of operation, the across-track beamwidth is
0.3° (0.6° for the Sonic 2022) and the along-track beamwidth is 0.6°: true Ultra High Resolution
sonar.
5.6.1.2 UHR Operation Suggestions
When operating at the high 700 kHz frequency, it will be necessary to increase Power and
Absorption significantly (Absorption set to 200dB/km). Along with this will be a possible increase in
Pulse Length, Gain, and Spreading Loss. As frequency increases so do the effect of attenuation and
this is why when in UHR mode, the sonar operating settings need to be increased to increase the
total power going into the water and the higher gain needed to receive the attenuated signal. As
stated, the UHR mode is for short-range operation.
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