Identifying the ADS-B signal received using RTL-SDR dongle.

Hi, I am trying to develop an algorithm to identify ADS-B signal recived by the RTL-SDR. So far I collected the IQSamples using the following command:

RX = comm.SDRRTLReceiver('0','CenterFrequency',1090e6,...
    'EnableTunerAGC',false,'TunerGain',60,'SampleRate',2.4e6,...
    'OutputDataType','single','SamplesPerFrame',262144,...
    'FrequencyCorrection',0)

I plotted the IQSamples and this is my result:

My next step is to set a threshold crossing for the noise floor. However, I am not sure how to implement the threshold. Can someone guide me to code the threshold?

Thank you.