FSK demodulator .vi uses Mod_Max_Eye.vi to estimate the optimal
sample location Ɩ at which SNR is highest. A transmitted packet
consists of preamble bit sequence of [101010…], byte
synchronization word followed by message bits. Synchronization word is
used to lock to the start of massage and parse the information bits.
Once information bits are extracted bit error rate is computed by
comparing the obtained bit sequence with the actual modulated bit
sequence. Developed graphical user interface of RTL-SDR receiver is
shown in figure-9.
Figure 8: Spectrum of the signal
at the output of various signal processing blocks and the eye diagram of
the demodulated signal indicating the quality of the received signal.