Distribution device, distribution system, and distribution method

A distribution system comprising:

• a sensor device;
• and
• a distribution device that distributes time information to the sensor device, the distribution device including
• a nonvolatile data storage medium that stores adjustment information of a time adjustment amount as a maximum unit of adjustment to be used for adjusting a local time,
• a hardware computing device that
• calculates a time difference between a reference time and the local time, and
• adjusts the local time by an amount equal to or less than the time adjustment amount, when the time difference is greater than the time adjustment amount, the time adjustment amount being determined based on an acceptable amount of error in a length of a synchronization interval during which the sensor device synchronizes a local time of the sensor device with the local time of the distribution device, and
• a network interface and control circuit that distributes time information of the adjusted local time to the sensor device, wherein
• the sensor device including
• a network interface and control circuit that receives the time information distributed from the network interface and control circuit, and
• a clock circuit that adjusts a local time of the sensor device so as to match the adjusted local time distributed from the distribution device.

A distribution method whereby time information is distributed to one or more sensor devices by a distribution device, the distribution method comprising:

• calculating a time difference between a local time of the distribution device and a reference time;
• adjusting the local time by an amount equal to or less than a time adjustment amount, the time adjustment amount being determined based on an acceptable amount of error in a length of a synchronization interval during which the sensor device synchronizes a local time of the sensor device with the local time of the distribution device;
• and
• distributing the time information of the adjusted local time to the one or more sensor devices at a predetermined time interval, the predetermined time interval is determined based on at least one of
• said acceptable amount of error
• the accuracy of a local time of the sensor device, and
• the accuracy of the local time of the distribution device.