# Not able to understand some operations in rtlsdr library in python

Here is the part of the program I am having problems with:

 samples = sdr.read_samples(16*1024)
power, _ = mlab.psd(samples, NFFT=1024, Fs=sdr.sample_rate /1e6)


NFFT is the data points iin each block of FFT and Fs is the sampling frequency. Now, here are my questions:

1. What does 12*1024 signify
2. why do we do sdr.sample_rate /1e6
• Do have a look at the matplotlib PSD docs... which say "The power spectral density Pxx ... The vector x is divided into NFFT length segments. Each segment is detrended ... and windowed ... The |fft(i)|2 of each segment i are averaged to compute Pxx" Mar 18 '21 at 5:27