I am loosing it... :((

[Jan]

I have read the replies on my post of "Msg to Sture" and I am definitly loosing it...


Can anyone tell me how the "Ping" looks like.


As I thought it would be:


1) I send a pulse to transducer (Pulse=Short & sharp)


2) This will send a single shockwave through the water


3) The size (length) of the wave will be about 3 mm for 500 kHz array


4) This single wave fans out and because of this loosing in strength.


5) When wave hits an object part of wave is send back as echo (It literary bounced back)


6) The echo is received by array.


7) Because it is likely that object is not exactly 90° on soundwave its likely that 1 object gives many echo's shortly after each other.


But still, each echo is just 1 wave without any extra signal superimposed on it.


Can anyone tell me how it really works ?


Regards, Jan

[bob]

Re: I am loosing it... (

Jan,


Sorry if I am confusing you. Perhaps others can explain it better. Let me try one more time..


I think we agree up to #6. After that, I think I see things a little differently..


As time progresses, the receiver gets signals from progressively further away objects. If an object, say is a sphere with a radius of 1.5 meter, is pinged, then the receive echo from the closest part of the sphere will start to arrive 1 ms before the echo from the widest part. (assmuming 1500 meters/second) Agreed?


If the sphere was half the size, then the difference in arrival time would be half as long. If the sphere was one tenth the size, then the difference in arrival time would be one tenth as long.


So as we want to resolve smaller details, we need to be able to track faster changes in the return signal.


In other words, to see smaller details, we need to increase the speed that the receiver can respond, otherwise known as the bandwith of the receiver.


Does this make sense?


-Bob

[Jan]

Re: I am loosing it... (

Bob,


Yes, sofar so good.


So, It is not that each pulse has frequencies superimposed but we are talking about a rapid sequence of single pulses.


I still do not understand what "Dynamic" is exactly.


Have a vague idea about it, but need to know more.


It looks like its important, so I need to know more about it.


So any help would be most helpful (funny sentence..)


Regards, Jan.