i wanted a zero crossing detector for a a acquired wave form.

[vicky]

it shoul detect the zero crossing of a wave

[Enrique]

The technique for finding a zero crossing is basically to detect a change in sign between two consecutive numbers. You need to evaluate the previous number sign with the current number.

A common way to do so is by multiplying the previous number and the current number. If the product is positive, both has the same sign and thus there was no zero crossing. If the product is negative, there was a zero crossing.

Make sure you are sampling you signal fast enough to accurately detect when the zero crossing occur. If you know your signal, you may easily calculate the exact moment based on your aqcuired information.

Best regards;
Enrique Vargas

[tom]

Add some noise and you've had it though!

Tom


Enrique wrote:

> The technique for finding a zero crossing is basically to detect a
> change in sign between two consecutive numbers. You need to evaluate
> the previous number sign with the current number.
>
> A common way to do so is by multiplying the previous number and the
> current number. If the product is positive, both has the same sign and
> thus there was no zero crossing. If the product is negative, there was
> a zero crossing.
>
> Make sure you are sampling you signal fast enough to accurately detect
> when the zero crossing occur. If you know your signal, you may easily
> calculate the exact moment based on your aqcuired information.
>
> Best regards;
> Enrique Vargas

[arbm]

I was looking for some thing like this.
Can you post some example to do the multiplying and
checking the sign
Thank you very much