The radar altimeter reports a fault of its own

What ArduPilot says:

• RangeFinder: Temperature alert
• RangeFinder: Altitude reading overflow alert
• RangeFinder: … alert
• RangeFinder: IF signal saturation alert
• RangeFinder: Voltage alert

An Ainstein LR-D1 radar altimeter (RNGFNDn_TYPE 42) sends fault flags with every reading, and ArduPilot reports them whenever they change: temperature, supply voltage, a saturated receiver (“IF signal saturation”) or a height the radar cannot represent (“Altitude reading overflow”). The distance may still arrive, but the radar itself says it should not be trusted.

What to do, most likely first

1. The radar's supply voltage is outside what it accepts, or sags when the motors load the battery.

   CheckA “Voltage” alert that comes with throttle points at the power wiring.

   FixFeed the radar from a regulator of its own, within the voltage its manual gives.

2. The radar looks at something too close or too reflective (the airframe, a metal surface), or it is overheating in a closed bay.

   FixGive it a clear view downwards and some airflow; if an alert stays on the bench with good power, the unit needs service.

Parameters to look at