FPGA Central

Hi,
I'm working with ultrasonic waves but I have the problem when I send
signal and listen for reflections of different surfaces. I need t
diferentiate the diferent echo surfaces. How can I do this? I dont kno
what type of filter I need, I supose I need an adaptative filter but I a
not sure. Can you help me, please? I would need some examples.

Thanx

Susan

Nesert wrote:
> Hi,
> I'm working with ultrasonic waves but I have the problem when I send a
> signal and listen for reflections of different surfaces. I need to
> diferentiate the diferent echo surfaces. How can I do this? I dont know
> what type of filter I need, I supose I need an adaptative filter but I am
> not sure. Can you help me, please? I would need some examples.
>
> Thanx
>
> Susan

Could you explain in more detail? Usually 'echo cancellation' means
that you want to remove an unwanted echo from a signal. If you know
the original signal and the signal with the echo added in, you can use
a standard technique (LMS or RLS) to remove it. That's easy to do.
But I think you have a different problem. It seems like it would be
difficult to determine a surface only from an echo. Different
materials absorb different amounts of signal energy. But if you don't
know the distances to the surface, I don't think that's helpful. You
might try looking for a book or journal articles on sonar.


-Todd

Nesert wrote:
> Hi,
> I'm working with ultrasonic waves but I have the problem when I send a
> signal and listen for reflections of different surfaces. I need to
> diferentiate the diferent echo surfaces. How can I do this? I dont know
> what type of filter I need, I supose I need an adaptative filter but I am
> not sure. Can you help me, please? I would need some examples.

The timing of the echo relative to a transmitted pulse carries range
information. Are you making use of that?

Jerry
--
Engineering is the art of making what you want from things you can get.
¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

[email protected] wrote:
> Nesert wrote:
>
>>Hi,
>>I'm working with ultrasonic waves but I have the problem when I send a
>>signal and listen for reflections of different surfaces. I need to
>>diferentiate the diferent echo surfaces. How can I do this? I dont know
>>what type of filter I need, I supose I need an adaptative filter but I am
>>not sure. Can you help me, please? I would need some examples.
>>
>>Thanx
>>
>>Susan
>
>
> Could you explain in more detail? Usually 'echo cancellation' means
> that you want to remove an unwanted echo from a signal. If you know
> the original signal and the signal with the echo added in, you can use
> a standard technique (LMS or RLS) to remove it. That's easy to do.
> But I think you have a different problem. It seems like it would be
> difficult to determine a surface only from an echo. Different
> materials absorb different amounts of signal energy. But if you don't
> know the distances to the surface, I don't think that's helpful. You
> might try looking for a book or journal articles on sonar.
>
>
> -Todd
>
Echo shape (broadness/decay) should be able to be used to determine
surface roughness and possibly material.

-Allan