Humminbird Side Imaging Forums
Side Imaging Forums => 898c SI => Topic started by: Spd 135 on June 11, 2015, 11:41:47 PM
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I have been experimenting with my transducer and have been getting some good images. By turning it sideways the detail comes out. You do, however, get some acoustic multipath and background reverberation as it shows on the side that is facing the surface. The depths are no good as the transducer is not facing the bottom.
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You can "aim" the HDSI 60° like we've already experimented with so the right SI main axis is pointing straight down ...(the main axis is the strongest part of the sound pulse) ...
(http://i477.photobucket.com/albums/rr134/rnvinc/HB/null_zpsc69ceb32.jpg) (http://s477.photobucket.com/user/rnvinc/media/HB/null_zpsc69ceb32.jpg.html)
You can see our experiments here ...
http://forums.sideimagingsoft.com/index.php?topic=5388.0 (http://forums.sideimagingsoft.com/index.php?topic=5388.0)
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If you connect your HDSI and a 2nd dual beam xducer to the AS SIDB Y cable ... You can then remove the left SI pin in the AS SIDB Y cable and render the left SI piezo dead to eliminate the left sound pulse from firing at the water surface ...
(http://i477.photobucket.com/albums/rr134/rnvinc/HB/null_zpsb4bd5280.jpg) (http://s477.photobucket.com/user/rnvinc/media/HB/null_zpsb4bd5280.jpg.html)
This allows you to sacrifice a $30 cable instead of a $270 xducer to achieve the same result (dead left SI pulse) ...
Rickie
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spd
what is the advantage of this set up ?? is DI better??
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The advantage is that the angle of attack is different. Instead of being from the top down it is sending the sound waves at a different angle. Remember, SONAR is underwater imaging. Imaging that the transducer is a camera. The angle you point is the picture you get. Of course, with a camera we stand where we get the best pic when we can. With sonar the dynamics are different. The moving boat and general proximity of the target also factor in to the image. You can make one pass and get a "lump" and on another pass you get a photo worthy image. The angle of the transducer can make a difference, and besides, "My transducer....my rules" ;D Mark Michaud
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spd
what is the advantage of this set up ?? is DI better??
Yes the DI in a HB SI unit is better when you "aim" the main axis of the right SI piezo straight down ...
The main axis is the strongest part of the sound pulse ...
But like Spd mentioned ... You need to do something with that left SI sound pulse ...(that is now "aimed" at the water surface) ...
Using a 2nd dual beam xducer and the AS SIDB Y cable allows us to remove the left SI pin in the AS SIDB Y cable to effectively remove the left SI sound pulse ...
Or you can leave the left SI firing like Spd did and just deal with the weird echoes received in the left SI piezo ...
Rickie
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rnvinc............pm sent