Abstract: Time synchronization is performed between the vehicle-mounted device and another device that is another vehicle-mounted device based on a data propagation delay time between the vehicle-mounted device and the other device. The vehicle-mounted device includes: a processing unit configured to receive, from the other device, request information that requests time information used for updating the propagation delay time, and transmit the time information to the other device; and a detection unit configured to detect an abnormality related to time synchronization, and acquire information regarding the detected abnormality.

Abstract: An on-board device includes a processing unit, and a storage unit storing a plurality of programs that are executable by the processing unit, in which the processing unit acquires information relevant to the presence or absence of update that is provided from a server outside a vehicle, stores the acquired information relevant to the presence or absence of the update in a sharing area by executing an input/output function that is different from an input/output function included in a basic program, and selectively executes the basic program or an update processing program after starting execution of a boot program, on the basis of the stored information relevant to the presence or absence of the update.

Abstract: An onboard device includes: a communication unit configured to communicate with an onboard device included in an onboard network; a detection unit configured to detect a new onboard device that is an onboard device newly added to the onboard network; and a sleep processing unit configured to, in a detected state where the new onboard device has been detected by the detection unit, transmit a sleep request for transitioning to a sleep state in synchronization with an onboard device included in the onboard network, to the new onboard device via the communication unit.

Abstract: An onboard device has an electricity storage, a control unit, a first communication circuit, and a memory. Power stored in the electricity storage is supplied to the control unit, the first communication circuit, and the memory. A main switch is provided on a power supply path extending from the electricity storage to the first communication circuit and the memory. When the terminal voltage of the electricity storage falls below a threshold value, the main switch is switched off.