Patent ID: 8744028

Claim:
A data communication system comprising a transmitting device which transmits data and a receiving device which receives the data, wherein the transmitting device comprises: a transmission clock generating circuit which generates a clock having a temperature characteristic in that a clock frequency varies with temperature; and a transmitting unit which wirelessly transmits data generated in synchronization with the clock to the receiving device, and wherein the receiving device comprises: a receiving unit which receives the data wirelessly-transmitted from the transmitting device; a reception clock generating circuit which generates a clock; a detecting unit comprising a frequency synchronization circuit which detects a frequency difference between the transmission clock frequency of the transmitting device and the reception clock frequency of the receiving device by using the reception clock frequency and the data wirelessly-received by the receiving unit wherein the transmission clock frequency is the frequency of the clock generated by the transmission clock generating circuit and the reception clock frequency is the frequency of the clock generated by the reception clock generating circuit; a storage unit which stores temperature characteristic information regarding the temperature characteristic of the transmission clock generating circuit; and a calculating unit which calculates a temperature of the transmitting device based on the frequency difference detected by the detecting unit and the temperature characteristic information stored in the storage unit.