$content =~ m{
    Frequency(\d+\sHz)\s
    Signal\sTo\sNoise\sRatio([\d.]+\sdB)\s
    Power\sLevel([\d.-]+\sdBmV)
    }xi or My_Die('content failed!');

##</code><code>##

$content =~ m/Frequency(\d+ Hz) Signal To Noise Ratio([\d.]+ dB) Power Level([\d.-]+ dBmV)/i
    or My_Die('content failed!');