# vrf detection of max and min in a signal

Question asked by papineni_vinod on Aug 11, 2005
Matt,

It wasn't my question, but "finding the zero crossing point is
relatively simple" is quite a bit confusing:( Care to post a VEE
example?

-Vinod

> Daniel,

> For each period, use the maxIndex and minIndex functions.

> If you have to find the start and stop position of each period,
> finding the zero crossing point is relatively simple.

> From the original time signal, form two signals.  For the first one,
> duplicate the last value and add it to the end.
> For the second one, duplicate the first value and add it to the
> beginning.  Now, multiply the two signals.  The crossing points are
> where the product is <= 0.  To find those,
> make an array corresponding to the total time of your signal (+ 1
> sample).  Use build coord to make a coord array of time (x) and
> product of the shifted signals (y).  Sort based on y using
> the sort formula, and only use those with y <= 0.  The corresponding
> x's are your zero crossing points.

> The result might have to be shifted by one sample.  Not sure -- did
> this about four years ago.  Let me know if it helps.

>
> -----Original Message-----
> From: Hynatec [mailto:oldenziel@hynatec.com]
> Sent: Thursday, August 11, 2005 11:34 AM
> To: VRF
> Subject: [vrf] detection of max and min in a signal
>
>
>
>

>
> I would like to solve the following problem.
>

>
> I made a registration of a oscillating signal.
>
> Now I would like to detect the values of the maxima and minima for
> each oscillation (period)
>
> Additionally I would like to detect the positions of these values
> (time scale) for instance referred to the intersection point of the
> zero-value (signal can be set symmetrically around zero)
>

>
> Has somebody already realized such e threat.
>

>
> I realized already something that works, but very complicated.
>

>
> I thank you in advance for a response.
>

>
> Best regards,
>

>
> Daniel Oldenziel
>

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around

---
You are currently subscribed to vrf as: rsb@soco.agilent.com
To subscribe send a blank email to "join-vrf@it.lists.it.agilent.com".
To unsubscribe send a blank email to "leave-vrf@it.lists.it.agilent.com".
To send messages to this mailing list,  email "vrf@agilent.com".
If you need help with the mailing list send a message to "owner-vrf@it.lists.it.agilent.com".