Stacked thresholds that layer sirens, zero debounce against punch-out sag, an alarm that fires before the first telemetry frame arrives, and the link-quality warning I never wired up.

Modern RC links send telemetry back from the receiver to the transmitter and OSD. Three numbers dominate: RSSI, LQ, and SNR. They measure the same link from different angles — and knowing which one to watch prevents both false alarms and missed warnings. What Each Metric Measures flowchart LR TX([Transmitter]) -->|RF …