Recent Posts91
General Discussion / Re: Mega SI transducer setup on flat bottom AL boat problems.
« Last post by Kenai on August 23, 2024, 09:24:52 PM »Thanks for explaining. Maybe I'm somehow confused by microphones and reproductions. Possibly I'm trying to apply here something which not belong in sonar technology. All you described to me until now is also true in audio technic. With one difference. Microphone is one device and reproducer the other. If I understood you correctly, the transducer uses the same piezo for both functions, emitting and also receiving sound. This is basically true also for reproducer, reproducer small enough could be also used as microphone, really unsensitive one, but it will work.
However, the ting I do not understand is how is position of object (echo return) degerminated in left-right plane. If transducer emits ping than waits for reflection and this reflection is processed.
This reflection has I believe 3 measurable parameters. Amplitude, frequency drift, and time of return. So how could be Left right plane determined ?
Take theoretic example to simplify things. We have something like this:
Infinite depth, so no return except from an iron hollow ball floating in water. It is in spaces covered by left and also right beam. Therefore, return echo will be from both left and right piezo pings. Also, those echos returns will be received by both piezoes. I suspect left and right piezo is not pinging in the same phase. Maybe they use also slightly difference frequency. So unit can determinate which echo is from which piezo for sure. However, both piezoes will detect that ball because it is in area coverage by both piezoes. Return from left piezo will be most likely a little fainter because of energy drop shown by emitting diagram you posted. Anyway, that don't rule out two balls from different material exactly in same depth and exactly in the same distance from transducer in left right plane. Even worse, if there will be only one piezo I still can't see how it will be possible for the head unit to tell on which side of the boat the ball is. I believe had unit can determinate only distance and amplitude of return, may be frequency drift. But not position. So if there are two possible solutions for the same distance, how can it tell which one is correct? 
However, the ting I do not understand is how is position of object (echo return) degerminated in left-right plane. If transducer emits ping than waits for reflection and this reflection is processed.
This reflection has I believe 3 measurable parameters. Amplitude, frequency drift, and time of return. So how could be Left right plane determined ?
Take theoretic example to simplify things. We have something like this:
