Received
- Nothing yet. Keep this tab open and the phone/laptop near the sender.
Two-way needs the receiver's “Talk back” on. It starts with a chirp handshake (fast first, then slower and longer-range), then measures the channel so each burst uses every frequency band as hard as it can take. If the link is too weak for that, it stays on chirps. Full duplex keeps sending while the receiver acks in a band it leaves free at 14–17 kHz; that saves the waiting but costs the band, so it is rarely faster.
One-way just repeats coded packets until you stop it, and any number of receivers can listen. Below noise uses LoRa-style chirps: each symbol's energy is spread over a whole sweep and gathered back into one FFT bin, so it decodes even when the signal is quieter than the background and invisible on the spectrogram. It's slow, meant for short messages across a room, through a wall, or at a whisper. Receivers always listen for it.
Plays a picture as sound so it appears in the spectrogram on any device that's listening — no decoding, just physics. Works best in a quiet room.