AnsweredAssumed Answered

vrf detection of max and min in a signal

Question asked by papineni_vinod on Aug 11, 2005

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


--- "BRADLEY,MATTHEW J (Non-A-Sonoma,ex1)"
<> wrote:

> 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.

> -Matt Bradley
> -----Original Message-----
> From: Hynatec []
> Sent: Thursday, August 11, 2005 11:34 AM
> To: VRF
> Subject: [vrf] detection of max and min in a signal
> Dear ladies and gentlemen.

> 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

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