Using it live: the method

An operator's reflex, to repeat every session:

1. Check the hardware. SDR detected (hackrf_info), the right antenna for the band, antenna in the clear.
2. Tune wide first. Sit at the centre of the band with a wide sample rate to see the whole picture, then zoom (narrower sample rate) on what interests you.
3. Set the gain. Raise it until signals rise out of the floor; back off as soon as the whole floor rises (saturation).
4. Read the Le waterfall (cascade temporelle) before concluding. The time dimension separates a stable carrier from a burst, a frequency hopper, or a wideband signal.
5. Identify before decoding. Width, stability, pattern → what kind of modulation? Many analyses (usefully) stop at presence detection, with no decoding.
6. Beware of ghosts. A peak moving the wrong way when you retune is often an alias (see Échantillonnage, Nyquist et aliasing) or saturation, not a real signal.

The academy automates steps 2–3 per mission (each mission tunes the radio for you) and trains your eye on steps 4–5.

👉 Get in position: First contact