A few figures from volume 1, as they appear in the book (the labels inside the figures are in Italian). Every plot is drawn from the data the chapter's program computes, every output is the program's real output: if the code changes, the figure changes with it. All the programs are in the downloads, MIT licensed.
Signals and numbers
I.1 — The samples of a tone, one by one: the first program of the book.I.2 — Two different tones giving the same samples: aliasing.I.3 — The measured signal-to-noise ratio against the formula, bit by bit.I.4 — Phasors: a tone as a rotating vector.I.5 — An I/Q signal: negative frequency becomes visible.I.5 — The spectrum after down conversion.I.6 — The spectrum of generated and measured white noise.
Analysis
I.7 — DFT resolution: two close tones, resolved or merged.I.8 — Measured times: the DFT, the FFT, the FFT with Vector.I.9 — The sidelobes of the windows, in dB.I.11 — A Barker code found by correlation, 20 dB below the noise.I.12 — Morse code read with the sliding DFT.I.12 — The sliding DFT: at every sample the oldest one goes out and the new one comes in.I.12 — The sliding DFT code, annotated.
Filters
I.13 — The frequency response of a window-designed FIR.I.14 — An optimal FIR by the Remez method: equal ripple over the whole band.I.15 — The IIR families compared: Butterworth, Chebyshev, Bessel, elliptic.I.16 — A notch that removes mains hum.I.17 — The all-pass 90° network for SSB.I.18 — The poles of a filter with 24-bit coefficients: the direct form pushes them out of the circle.I.19 — The CIC decimator: integrators, decimation, combs, no multiplications.I.19 — From 192 kHz to 6 kHz in one step or in two: the same result, a quarter of the work.I.19 — Polyphase decimation, annotated.I.20 — From 48 to 44.1 kHz with a single polyphase filter: the program output.I.20 — Two sound cards with two crystals: the queue without correction and with the adaptive resampler.I.21 — The complex filter: the same low-pass, moved entirely to positive frequencies.I.21 — The unwanted sideband of SSB with the Hilbert transformer.
