A simple peak finder

findPeaks[list_] := (list // BlockMap[(#[[1]] < #[[2]] > #[[3]] &), #, 3, 1] & // Position[True]) + 1

On Mike's sample data

peaks = findPeaks@data;
values = Extract[data, peaks];

ListPlot[{data, Transpose[{Flatten@peaks, values}]}, 
 PlotStyle -> {Automatic, Red}]

Please post the code you used to generate the plot. There are no negative values in Example.txt but the plot in OSC-Signal.jpg has negative values.

Hi Rohit

Sorry the data is positive, and I am looking for the bottom position. So I multiply it with (-1) and looking for the peaks instead

Thanks for looking into my problem.

Xiaxing

Without a better understanding of your requirements, I think something like this might work:

data = {100, 3, 2, 103, 102, 5, 4, 2, 105, 104, 103, 3};

findPeaks[ data_List, tolerance_List] := Module[
   {
    peaks = FindPeaks[data]
    , lastPeak = {-Infinity, -Infinity}
    , forward
    , reverse
    },
   forward = Map[
     With[
       {
        retVal = If[
          And[
           First[#1] -  First[lastPeak] <= tolerance[[1]],
           Last[#1] - Last[lastPeak] <= tolerance[[2]]
           ]
          ,
           Nothing
          ,
          #1
          ]
        }
       ,
       lastPeak = #1
       ] &
     ,
     peaks
     ];


   reverse = Map[
     With[
       {
        retVal = If[
          And[
           First[#1] -  First[lastPeak] <= tolerance[[1]],
           Last[#1] - Last[lastPeak] <= tolerance[[2]]
           ]
          ,
           Nothing
          ,
          #1
          ]
        }
       ,
       lastPeak = #1
       ] &
     ,
     Reverse[forward]
     ];

   Reverse[reverse]

   ];

findPeaks[data, {3, 3}]

Rohit:

Thanks again for teaching me a new trick. I can see how BlockMap[] can be very useful.