Learn SDR 04: What's Inside an SDR: Designing one from First Principles

Learn SDR with Professor Jason Gallicchio at Harvey Mudd College Lesson 4: What's inside the SDR? Designing one from first principles. Zero-IF Direct Conversion Incoming real RF signal is r(t) This gets split, multiplied by cos and sin, low-pass filtered, sampled, and returned as a sequence of complex numbers. r(t) = A cos(2πft+ϕ)  turns into z(t) = A e^iϕ e^(2π(f-f0)t) If I were to do it again, I'd draw more pictures of the RF waveform. HW1: Do the trig identities to trace through the direct conversion architecture. Extra Credit  : Design a transmitter by reversing the process: Turn z(t) = A e^iϕ e^(2πft) into r(t) = A cos(2π(f+f0)t+ϕ) https://gallicchio.github.io/learnSDR... All GNURadio flowgraphs are at: https://github.com/gallicchio/learnSDR --- Learn SDR with Professor Jason Gallicchio