MATLAB Answers

how to find the bottom peaks in the graph?

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RAVI
RAVI on 1 Oct 2018
Commented: Thumree Sarkar on 6 Feb 2019

how to find decreasing order of peaks in graphs, so that how much graphs goes deeper at higher frequencies (plz refer image.).i have to find the values so that my graph reaches as deeper as possible at higher frequency.

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RAVI
RAVI on 1 Oct 2018
bottom peaks not top peaks of the image file
Thumree Sarkar
Thumree Sarkar on 6 Feb 2019
data= - data, then use findpeaks, you will get the bottom peaks.

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Accepted Answer

madhan ravi
madhan ravi on 1 Oct 2018
Edited: madhan ravi on 3 Oct 2018
[locs,idxs]=findpeaks(-y) %EDITED

If y is the function of the plot -y will give the minimum of the function.

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RAVI
RAVI on 1 Oct 2018
i want multiple peaks but it gives only 64 at 700Mhz. It should also give -36 at 150MHz and many more.

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More Answers (2)

Image Analyst
Image Analyst on 3 Oct 2018
Find valleys by sending the inverted vector into findpeaks() and finding the peaks. Then you have to invert again to get the positive values (since you have inverted/negated it):
% Find values and locations:
[negPeakValues, indexesOfValleys] = findpeaks(-signal);
% Invert values to get the original, non-inverted values.
valleyValues = -negPeakValues;

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Jim Riggs
Jim Riggs on 3 Oct 2018
Here is a similar problem. To find the bottom peaks, just change one line from
if(D(i) >0 && D(i+1)<0
to
if(D(i)<0 && D(i+1)>0

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