Data receiving apparatus, data transmission apparatus and data transmission system

A data receiving apparatus which communicates with a data transmission apparatus, the data receiving apparatus comprising:

• a clock unit which indicates a date and time;
• a receiver configured to receive a first packet and a second packet for one-way communication transmitted from the data transmission apparatus;
• and
• a calculator configured to (1) store, in response to the first packet including first date-and-time data indicative of a first local date and time in the data transmission apparatus and information indicating that the first date-and-time data is available for date and time association, the first local date and time and the date and time indicated by the clock unit in a memory, the date and time being associated with the first local date and time indicated by the first date-and-time data, the date and time being stored as a reference date and time, and (2) calculate, in response to the second packet including sensor data and second date-and-time data indicative of a second local date and time in the data transmission apparatus and associated with the sensor data, third date-and-time data based on a difference between the first local date and time stored in the memory and the second local date and time indicated by the second date-and-time data, and based on the reference date and time stored in the memory.

A data transmission apparatus comprising:

• a clock unit indicative of a date and time;
• and
• a transmitter configured to transmit (1) a first packet for one-way communication, the first packet including first date-and-time data and information, the first date-and-time data being indicative of a first date and time of the clock unit, the information being indicative of the first date-and-time data which is available for date and time association, and (2) a second packet for one-way communication, the second packet including sensor data and second date-and-time data, the sensor data being measured by a sensor, the second date-and-time data indicative of a second date and time of the clock unit at measurement of the sensor data,
• wherein a data receiving apparatus is configured to (1) store, in response to receipt of the first packet, the first date and time and a third date and time indicated by the second clock unit in a memory, the third date and time being associated with the first date and time of the first clock unit indicated by the first date-and-time data, the third date and time being stored as a reference date and time, and (2) calculate, in response to receipt of the second packet, third date-and-time data based on a difference between the first date and time stored in the memory and the second date and time indicated by the second date-and-time data, and based on the reference date and time stored in the memory.

A data transmission system, comprising:

• a data transmission apparatus;
• and
• a data receiving apparatus which communicates with the data transmission apparatus, wherein
• the data transmission apparatus comprises:
• a first clock unit indicative of a date and time;
• and
• a transmitter configured to transmit a packet for one-way communication,
• wherein the packet includes sensor data measured by a sensor, and date-and-time difference data indicative of a difference between a date and time of the first clock unit at measurement of the sensor data and a date and time of the first clock unit at transmission of the packet,
• the data receiving apparatus comprises:
• a second clock unit indicative of a date and time;
• a receiver configured to receive the packet transmitted from the data transmission apparatus;
• and
• a calculator configured to calculate, in response to receipt of the packet, date-and-time data indicative of a measurement date and time of the sensor data from the date-and-time difference data using the date and time of the second clock unit.

A data receiving apparatus which communicates with a data transmission apparatus, the data receiving apparatus comprising:

• a clock unit indicative of a date and time;
• a receiver configured to receive a packet of one-way communication transmitted from the data transmission apparatus, the packet including sensor data and date-and-time difference data associated with the sensor data;
• and
• a calculator configured to calculate, in response to the packet, date-and-time data indicative of a measurement date and time of the sensor data from the date-and-time difference data using the date and time of the clock unit,
• wherein the date-and-time difference data is indicative of a difference between a local date and time at which the sensor data associated with the date-and-time difference data was measured by a transmission source of the packet and a local date and time at which the transmission source of the packet transmitted the packet.

A non-transitory computer readable medium storing instructions to cause a processor to transmit a packet for one-way communication from a data transmission apparatus;

• and/or receive and process the packet by a data receiving apparatus, wherein:
• the packet includes sensor data, first date-and-time data and information, the first date-and-time data being indicative of a first local date and time in the data transmission apparatus and associated with the sensor data, the information being indicative of whether the first date-and-time data is available for date and time association, and
• the data receiving apparatus performs a process that comprises:
• determining whether or not the first date-and-time data is available for the date and time association based on the information included in the received packet,
• setting a date and time of a clock unit comprised by the data receiving apparatus as a reference date and time by associating the date and time of the clock unit with the first local date and time indicated by the first date-and-time data included in the received packet, if the first date-and-time data is determined to be available for the date and time association, and
• calculating, in response to receipt of the packet, date-and-time data indicative of a measurement date and time of the sensor data from a date-and-time difference data using the date and time of the clock unit, date-and-time difference data being indicative of a difference between the first local date and time at measurement of the sensor data and a second local date and time in the data transmission apparatus at transmission of the packet.