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View Full Version : What is meant by 90 degree sonar on a fish finder?



mighty
02-22-2006, 12:57 PM
How do you know where the fish are, like are they directly under the boat?
I ask because I just got blessed with and I am looking into getting a Matrix 17 fish finder.
I nothing about fish finders.

Help ME PLEASE.

Thanx

Moose1am
02-22-2006, 01:13 PM
Mighty:
90 deg cone angle is just a large cone that covers more of the bottom of a lake. Most cone angle are smaller. Mine is just 20 deg. Here's a more detailed explaination of how sonar works.


Sound waves travel out in an ever expanding wave. The effectiveness of that wave for finding objects on the bottom and getting sound waves to bounce off those objects with enough energy to make the return trip back to the transducer and be recorded is how they determine the cone size. Some waves don't return and are lost. A narrow cone only shows a small part of the bottom. A wider cone will show more area of the bottom. There are some limitations that one must know about when trying to interpret the recordings.


The new thing these days is to take a very narrow cone size and using multiple pings (transmission) that are moved around like a flash light beam in the dark. You actually paint the bottom with multiple narrow overlapping sound waves. We do this with radar beams also. The term is phased Array Radar and I think that they are doing the same thing with sonar beams.

I am adding some pictures that I scanned into my computer to help you and anyone else that has a hard time picturing what the sonar waves are doing.

http://i49.photobucket.com/albums/f263/Moose1am/Fig1Fig2Fig3.jpg


http://i49.photobucket.com/albums/f263/Moose1am/Fig4.jpg

http://i49.photobucket.com/albums/f263/Moose1am/Fig5Fig6Fig7.jpg

http://i49.photobucket.com/albums/f263/Moose1am/Fig8.jpg

http://i49.photobucket.com/albums/f263/Moose1am/Fig9Fig10.jpg

http://i49.photobucket.com/albums/f263/Moose1am/Fig11.jpg

http://i49.photobucket.com/albums/f263/Moose1am/Fig12Fig13.jpg




How do you know where the fish are, like are they directly under the boat?
I ask because I just got blessed with and I am looking into getting a Matrix 17 fish finder.
I nothing about fish finders.

Help ME PLEASE.

Thanx

freeflow_23
02-22-2006, 01:29 PM
90* is the size of the sonar cone. I think this size is good for freshwater. Water that is 5' to 40'. You'll see lots of ground under your boat.

30* cone is very narrow.

unknown 5
02-23-2006, 08:40 AM
I have a 90 degree cone angle on my fishfinder and I can see lots of things others would miss with my fishfinder. I wouldn't go fishing without it.

jimfish
02-23-2006, 09:54 AM
Hey guys used to be bothered by same problems ,reason being that after Mar.1 and up till fall i wont be in over10 ft. of water. found how much you miss even with a 90* cone angle. I have HUMM.400tx hooked to a wide side trans. lets me look to both sides at same time up to 120 ft. when i spot fish i bring my scale down to pinpoint. Have had a lot of success.

KINGFISHER
02-23-2006, 10:17 AM
Moose1am I am glad that you are posting again. You have always had the most interesting thing to say. This is an example! I did not have any idea how a finder works. This is great! I have always wondered what is that on my screen? Now maybe I will I will know. Thanks! Don

mighty
02-23-2006, 01:32 PM
Thank yall