Simple Period Event Handler

I need a simple event handler to determine the period (from 102 to 102). See sample data below. Any help would be appreciated

     Time     Data
         0  102.0000
    0.2500  102.3807
    0.5000  102.4622
    0.7500  102.2247
    1.0000  101.7033
    1.2500  100.9747
    1.5000  100.1278
    1.7500   99.2644
    2.0000   98.4979
    2.2500   97.9225
    2.5000   97.6039
    2.7500   97.5848
    3.0000   97.8592
    3.2500   98.3845
    3.5000   99.1086
    3.7500   99.9533
    4.0000  100.8124
    4.2500  101.5771
    4.5000  102.1498
    4.7500  102.4508
    5.0000  102.4417