Author Topic: How does sonar transducer receives echoes  (Read 1037 times)

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Offline KabonaTopic starter

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How does sonar transducer receives echoes
« on: February 05, 2012, 07:47:09 PM »
Hey all! I am wondering if anyone can try and give me a rough idea on how a transceiver on a let's say a fish finder interprets echo returns.

I apologize for my rough sketches that were done on my iPad.

First thing.
 When a echo bounces off something and is returning to the receiver, is it one large echo that gets measured in size? Or a bunch of little echoes returning?




Second thing.

How does the receiver even get all the returns within its cone angle when the signals are getting sent out on oblique angles.



And last thing.

 A top down view looking down the cone of a transducer would look like this with fish under it.


Most fish finders give you a side view like this...


Can transducers calculate echoes to display them on a screen in way where it actually looks like a top down view? Or can transducer not calculate the distance between objects in a top down view in returned echos.

If anyone could help me comprehend these things a little better it would be appreciates.
Thanks


Offline KabonaTopic starter

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Re: How does sonar transducer receives echoes
« Reply #1 on: February 05, 2012, 08:47:59 PM »
Also how does a fish finder calculate and display such a ...well... display? :s



The new readings come in at the line at the very right of that display where it says 0-60. When a pulse goes out, does it take everything returned withing the cone and display it on the one pixel column?

If the above statement is true then the transducer shoots out a pulse and will wait back for multiple returns off that pulse to display different depths with multiple pixels on one pixel column on the display. So does this mean that a transducer can only send out one pulse and wait for all the returns before it can send out the next one? Or are transducers capable of differentiating between multiple pulses.



Alsoo return echos change somehow when bounced of either hard or soft surfaces?

sorry... I probably sound like a confused idiot by now..:s ..... I am more of a software guy that electronics
« Last Edit: February 05, 2012, 09:04:59 PM by Kabona »

Offline Soeren

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Re: How does sonar transducer receives echoes
« Reply #2 on: February 05, 2012, 09:04:55 PM »
Hi,

Can transducers calculate echoes to display them on a screen in way where it actually looks like a top down view? Or can transducer not calculate the distance between objects in a top down view in returned echos.
Since the fish finder interprets the return time of the pulse sent out, it can only estimate the distance and the magnitude and perhaps "fuzzyness" of the echo to estimate the amount of fish - not the exact position of each fish though.
I'd think that clever software can do wonders though and analyzing the behavioral patterns of different species of fish at different times of the day and year might make it possible to be a lot more precise, but I'd think the algorithms of each make of fish finder will be a closely guarded secret.

And just to be precise, the transducers does not calculate anything, they just send and receive the pulses and need a processor of sorts to do all the math - I wouldn't be surprised to find DSP's doing the hard work these days.

Are you trying to make a fish finder yourself?
Regards,
Søren

A rather fast and fairly heavy robot with quite large wheels needs what? A lot of power?
Please remember...
Engineering is based on numbers - not adjectives

 


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