Thread: Sonar Quiz #45

In the SI view below ...:

#2 is obviously closer to the boat than #3 ...

So explain why would #3 give a better return than #2 if #3 is farther away ...??



Rickie

#3 is out in the meat of the SI beam. The #2 is in the marginal fringe area directly under the boat. I am curious why #2 doesn't give as much relief to where you can see that the block is elevated in the DI image. I guess if you are shooting across the top at an angle you get some shadowing and the unit sees it as raised up, whereas if you are directly over the top it cant really tell that there is a difference between the top of the block and the lakebed. I guess that one could just be all silted in also, the portion that laps over from the bottom contour looks like it is a little softer.

I GO OVER SUNKEN BOATS OFTEN AND ALWAYS GET BETTER PIC TO SIDE WITH SI,STRONGER SINGAL TO SIDE THAN STRAIGHT UNDER BOAT PLUSE SI TAKES A BETTER PIC OF OBJECT ON ANGLE WHERE IT CAN PASTE IT IN BETTER,EVEN A PAINTER CAN PAINT A BETTER PIC OF BOAT ON ANGLE BETTER THAN SIDE WAYS

I agree with both above. But since this was taken with an onix, I'm going to say it is sunk in softer bottom further as seen in the 2D view. But I don't understand why it shows up so curved on DI view?

PONTOON,ON DI, ONIX OR NOT ,DRAW A FLAT PIC AND SO CORNERS ARE FARTHER AWAY AND SO MUST BE DRAW DOWN HILL FARTHER FROM DUCER BUT IN LINE WITH REST OF CONCRETE SLAB,IF YOU WOULD PAINT A OVERHEAD PIC OF SLAB YOU ALSO WOULD HAVE TO PAINT THAT WAY,ON FLAT OBJECTS IT IS THE ONLY WAY TO DO IT,I AGREE ONE SLAB IS DEEPER IN THE MUD

Here's a better shot of those concrete slabs.they have cables attached,that hold the floating docks in place...

I like the way Orange worded his answer ... #3 is out in the meat of the SI beam. The #2 is in the marginal fringe area directly under the boat.

The SI sound pulse is strongest along its "Main Axis" ...which is 30° from horizontal ...

Above and below this 30° - the sound pulse is attenuating (getting weaker) ...



So like Gene mentions ... Better SI pix will come from objects that are off to the side a little in the stronger part of the SI beam sound pulse ...

Good job again guys ...

Cool pic kosmo ...

Rickie

KOMOS,THAT IS A GREAT PIC,FROM ONIX? DID IT DRAW OUT THOSE DOCKS LIKE THAT OR DID YOU PASTE SOME OF IT IN?WOULD LOVE TO SEE CAMERA PIC OF THAT BIG DOCK,AGAIN IF ALL THAT IS JUST SI ,DON'T SEE HOW YOU GOT SUCH A PIC UNDER THAT DOCK

Originally Posted by genec

KOMOS,THAT IS A GREAT PIC,FROM ONIX? DID IT DRAW OUT THOSE DOCKS LIKE THAT OR DID YOU PASTE SOME OF IT IN?WOULD LOVE TO SEE CAMERA PIC OF THAT BIG DOCK,AGAIN IF ALL THAT IS JUST SI ,DON'T SEE HOW YOU GOT SUCH A PIC UNDER THAT DOCK

That's all Onix.I'll be down that way today.I'll see if I can get you a video,to look at (maybe)

So if using 800 MHz looking for bottom structure is the rendered DI almost useless? Can you miss things directly under the boat on SI completely?