APPARATUS AND METHOD FOR TRANSMITTING DATA BY RADIO

An apparatus for transmitting data by radio to a receiver is described. The apparatus comprises a controller having an input for receiving data; a local clock forming part of a phase locked loop adapted to be synchronised at predetermined intervals to a master clock signal; and a time stamp circuit adapted to add time stamp data from the local clock to the data to form time stamped data. The apparatus also comprises a transmitter circuit adapted to receive the time stamped data and to transmit the time stamped data by radio to the receiver. The phase locked loop allows the local clock to remain in synchronism with the master clock without requiring the master clock to be read for each item of data transmitted. This enables a more efficient use of hardware resources. A wireless sensor, wireless telemetry system and method of transmitting data is also disclosed.