1.1 Evolution of Radio Frequency Electronics Toward SDR1.2 The Complex Envelope and the Justification of the IQ Structure1.3 Complex Number Manipulation1.4 GNU Radio and GNU Radio Companion1.5 Sample Rates, Decimation and Aliasing1.6 Low-pass Filtering or Working on Upper Nyquist Zones1.7 ADC and DAC Resolution1.8 Power Spectral Density Display with the Frequency Sink1.9 ConclusionReferencesNotes