Part 2 — Telemetry: the life of a signal

Part 1 drew the map. This part follows a single tracker message across it: from the radio frame a device assembles in the cab, through the front door that authenticates and normalizes it, to the grade that decides how far to trust it, and finally to the live answer a dispatcher reads — is this truck driving, parked, GPS-blind, or gone dark?

One idea threads the whole part, and every chapter earns it back: a silent GPS does not mean a silent truck. A parked truck stops sending positions on purpose while its tracker keeps proving it is alive, and telling that apart from real failure is the quiet work this part exists to do.

• Trackers and what they report — the device families Korido normalizes into one shape, the two kinds of message (position fixes and telemetry-only status frames), the signals a frame carries, and the BLE probes that read a fuel tank's level.
• The ingestion pipeline — how a message authenticates, is validated field by field, is batched under a hard size budget, and becomes a durable positions row — with three archives catching everything that cannot follow the happy path, so no real telemetry is silently lost.
• Position quality — the quality ladder that grades every fix from a trusted reading down to an audit-only reject, and the rule underneath it: only telemetry the engine actually trusts may move a truck's state.
• Liveness — the two-clock model (is the tracker alive? do we know where it is?) and the states it produces: driving, stopped, idle, "Stationné — dernière position connue", "Sans GPS", and offline.

How it connects

• Before: Part 1 — Korido sets up the product, the roles, and the GPS source-of-truth principle this pipeline depends on.
• Next: Part 3 — The fleet engine turns the graded stream of positions into trips, stops, gaps, and fuel events.