Humminbird Side Imaging Forums
Images, Snapshots and Videos => General Pictures and Screen Captures => Topic started by: Scrutch on May 05, 2011, 10:10:13 PM
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These images are from Barkley Lake. I don't want to spoil it for those who like to guess so I'll wait for a few guesses until I give the answer. PM me if you can't wait for the answer.
Once I reveal the answer, I have a question for all you experts.
[attachment=1]
[attachment=2]
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one more...[attachment=1]
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Some type of fireworks? >:D Roddy
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Un mm, may be some cocon that was left perhaps? :)
Regards,
Gustavo
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Nice sample.
Could it be... A large 30' diameter floating fish-cage or similar structure, floating on the surface, to the side of the boat?
Tore
tore@sonartrx.com
http://www.sonartrx.com (http://www.sonartrx.com)
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cast net
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biosphere?! ;D
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Elvis and Jimmy Hoffa's Hideaway!!!!! >:D ::)
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Attack of the Killer Jellyfish!
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i no what it is but im not telling :o :o :o :o :o :o :o :o :o :o :o :o
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These are actually from Barkley, not Kentucky sorry bout that.
I passed within a few inches of the barge moorings to see if I could mark some fish stacked up behind them. The dam had 10 gates open which created a pretty strong current and the fish were hanging out in the current breaks behind them. If you look closely you can see the fish.
Interesting question though...
Why did the LEFT side show an echo as well? I passed by them on the right only. You'll notice that there's a strong echo on the right side and a weaker one on the left. Obviously there's nothing on the left so why is that reflection there?
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Wow! That's some strong current.
Remember that the left and right Si sonar beams have some overlap. The left Si beam may have picked up some of the current on the far edge of it beam.
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I don't quite understand your answer Greg.
Here's a pic of the barge moorings...
[attachment=1]
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Are yu sure that is a picture of the current? It looks more like one of the barge moorings. Could your left and right SI transducers be switched? I have heard of this transducer problem a couple of times. Manufactured wrong..
Chuck
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Hi Scrutch,
As the sound emitted by the right-side transducer returns, the return signal is perhaps strong enough to be picked up by the left-side too? ...but with a much lower signal level, since the element is facing the opposite direction. (Or as Sonar2000 suggests, perhaps there is some "bad wiring" between the channels?)
Do you see the same "mirroring-effect" when passing by other vertical structures or walls?
(..wooden piles, concrete piles, sea-wals etc.?)
Perhaps repeat the test, passing with the mooring on your left side to see if there is a weaker return on your right (i.e. see if the effect is identical, but mirrored))
Tore
tore@sonartrx.com
http://www.sonartrx.com (http://www.sonartrx.com)
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I'm not totally sure why the echo is reflected in the left SI pane. Glenn over at Bass Resource.com http://www.bassresource.com/bass-fishing-forums/topic/86239-kenlake-roadtripperscan-you-guess-what-these-are/ (http://www.bassresource.com/bass-fishing-forums/topic/86239-kenlake-roadtripperscan-you-guess-what-these-are/) offered the same suggestion as SonarTRX... The echo is so strong due to the fact that I passed within a few inches of the concrete and steel barge mooring that the left side picked up the echo as well.
I haven't noticed any other reflective echoes, but I haven't been watching for them either. I'll pay closer attention next time out. I hope there aren't any issues. I just got this thing dialed in.
I live in northern Indiana, so I can't scan the moorings again anytime soon. I might be able to find a seawall suitable enough to substitute and repeat the effect.
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Scrutch, thanks for the additional posting. I am getting a clearer picture of your sonar run now.
What was first indicated as water current is now more obvious as the mooring pilings.
Now that I am seeing the bigger picture it seems your transducer is working ok..
Remembeer that there are two SI elements in the transducer. One left and one right.
The beam is said to be be 89 degrees each but in fact may be a bit wider.
Your weaker image is a product of the beams overlapping and the signal strength of receiption.
You are not seeing anything uncommon for the HDSI..
Depth does come into play and at deeper depth you will not se as much reflection unless the object is sticking up from the bottom.
Great pictures for your trip and great work.
Chuck
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[attachment=1] I get the echos when too close to bridge pier.
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Not uncommon.....It all has to do with the angle, the depth and the transducer arrays.
If it is a problem then turn off one side of the array. As in right transducer only..
Chuck
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I don’t think that you are seeing a sonar reflection from the right Si sonar beam. I think that you passed close enough that the mooring piling was in the left Si sonar beam. There is overlap between the left and right Si sonar beams (that is how we get some of the Di sonar) and how much depends on things like the water depth and water conditions. You were just close enough to capture the mooring piling on both Si beams. Either that or it was giant killer jellyfish!
Setting the unit to display only one Si sonar beam does not turn the other one off. You would have to place something on the transducer itself (cork?) to absorb and block the Si sonar from one side or cut into the cable or break a transducer connector pin to keep the unit from transmitting to both the left and right Si sonar beams.
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Using only one side of the transducer will then show only that received signal. Which might be what he wants.
It would be nice if HB would allow the transmitter to be selectable on beams...
Chuck
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I don’t think that you are seeing a sonar reflection from the right Si sonar beam. I think that you passed close enough that the mooring piling was in the left Si sonar beam. There is overlap between the left and right Si sonar beams (that is how we get some of the Di sonar) and how much depends on things like the water depth and water conditions. You were just close enough to capture the mooring piling on both Si beams. Either that or it was giant killer jellyfish!
Setting the unit to display only one Si sonar beam does not turn the other one off. You would have to place something on the transducer itself (cork?) to absorb and block the Si sonar from one side or cut into the cable or break a transducer connector pin to keep the unit from transmitting to both the left and right Si sonar beams.
Very interesting Greg. I need to chew on that a little. I had a picture in my head of what the beam coverage looked like (see 1198 manual, page 68,69). I'm trying to digest what you're describing as the "true" shape of the beams, or should I say BEAM. Should I be thinking in terms of ONE fan-shaped beam?
You've certainly piqued my interest.
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You're telling me that this is only PART of the beam shape?
[attachment=1]
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I don't quite understand your answer Greg.
Here's a pic of the barge moorings...
(Attachment Link)
if you get some time later when the gates are closed go on over in front of the dam and see whats there. thats were i got the picture that part of my logo to the left
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Scrutch,
It can be more like this (beams are not drawn to scale).
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Scrutch,
You can widen or narrow the "official beam angle" by adjusting the sensitivity:
High sensitivity setting will allow for weaker signals to be detected (Even targets outside of the "official beam angle" might be visible)
Low sensitivity settings might only bring out targets in a beam angle narrower than the "official beam angle".
The beam angles shown in marketing information is usually a simplistic sketch of the areas covered by the beam for a given reference signal level.
Since you were passing really close to the feature, you could perhaps lower the SI sensitivity to prevent the feature from being picked up by the opposite SI transducer element.
There might be something else going on here too, but it would be interesting to hear Humminbirds offical explanation to this, and perhaps a more detailed explanation for how they determine the beam angle for their systems?
Tore
tore@sonartrx.com
http://www.sonartrx.com (http://www.sonartrx.com)
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Don’t know that I could add anything official to this. The sonar beams are measured at the -10db level while in a laboratory water tank. The actual sonar beam can be wider or narrower mainly due to water conditions.