Thread: Sonar Quiz #23

Not sure, but I'm tuning in for the answers.

Darned if I know, I'm with Searay, waiting for the answer!
I had an answer, until I killed my own answer! LOL

Tell us !!! Is it the size of the cone angle?

Narrower cone? Fish goes from one side of cone to center and back out quicker with a narrower cone, even tho the cones are travelling at the same speed

Greater cone angle from the 83kHz (35deg) picks up more detail than the 200kHz (12 or 20deg).

... cp

Originally Posted by rnvinc

The image below shows a split frequency screen ...(credit to Peter at continuouswave)...

Same sonar history ... 200kHz on the left and 83kHz on the right ...

Explain why the 200kHz doesn't paint the pretty arch like the 83kHz does (in this example of the same echo targets)...



Rickie

I don't know what cone angle the 200 has but it looks like 12 degrees as a 20 would arch fish. The 83 is approaching 60 degrees at 3db therefore the fishes depth is in the cone longer.

I AGREE ,CONE WIDER

Great job guys ...

Now let's look at the 2 most important factors that affect the difference in the way this example paints the 200kHz targets vs the same targets in the 83kHz ...

1. Time duration of the target in the cone beam ...
2. Target distance from xducer as it passes thru the cone beam ...

note: online right triangle calculators are cool




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It's important to note that all makes of 200kHz are not exactly 20° ... And all makes of 83kHz are not exactly 60°...these beam angle values were chosen to show the comparison of how the echo target is painted in a "narrow cone beam" vs a "wider cone beam"...

Rickie