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Old 09-25-2014, 09:09 PM   #9
JDCAVE's Avatar
City: Lions Bay, BC
Country: Canada
Vessel Name: Phoenix Hunter
Vessel Model: Kadey Krogen 42 (1985)
Join Date: Apr 2011
Posts: 2,271
The work that my team did with our agency using dual frequency imaging sonar clearly showed to us that degradation of the beam resolution with extended ranges was severe enough that we usually only operated it on the high frequency setting. We operated a longer range unit for several years and continue to do so, but the image quality makes this unit marginal at best at the 40 m. range setting. Long range units are no longer the preferred choice going forward.

FYI, figure 6 page 12 of the attached link below shows a schematic of the difference between images for split beam and dual frequency imaging sonar. The bullets discuss the range limitations of such units...

Again, I guess my point is, the devil is in the details.

I'm curious what the Simrad units cost? As I have mentioned Simrad produces some very high end technology but they are new comers to imaging sonars as the technology had been proprietary until the US govt, allowed it to be released to research agencies such as ours. Does Simrad reveal details of the technology? In the past they have been "closed mouth". I'd be curious about technical detail about the number of beams deployed, their geometry and the resolution between two closely spaced targets of known size at range. It's that kind of information that is required in order to assess the claimed capabilities.

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