1 From the above plotted Signal Data and SignalDataNoise vs

1) From the above plotted Signal Data and SignalDataNoise vs time, What difference you observe in the plots?

2) From the above plotted power spectral density of SignalData and SignalDataNoise as a function analog frequency (in Hz), what difference you observe in the plots?

Solution

1. In the 1st plot:

Signal data (Blue) graph indicates one cycle of ECG signal

Signal plus noise data (Green) indicates the ECG with 50 Hz powerline interference. It means 50Hz noise signal coming from its power source is continuously added with the actual signal.

2. Generally power spectral density indicates the strength of the frequency components present in the given signal. In the given plot, blue graph which is the PSD of signal data, which indicates more contribution at lower frequency components (<25Hz general frequency range of ECG).

green signal indicates the PSD of signaldata plus noise which shows dominating power magnitude at 50 Hz as compared with the actual signal frequency components. This is because of the addition of power line interference(50Hz).