US Patent 9007209 Cargo and door sensor

Implementations for a system to receive a message indicating that an ambient light level measured by an ambient light sensor within a container exceeds a first threshold value or falls below a second threshold value; in response to the message indicating that the ambient light level exceeds the first threshold value, activate a cargo sensor; and in response to the message indicating that the ambient light level falls below the second threshold value, de-activate the cargo sensor.