Patent ID: 9140547
Filing Date: 2015-09-22
Classification: G01B,H04B

Abstract:
1. A measurement apparatus comprising: a measurement probe comprising a first station, and a coordinate positioning apparatus comprising a second station, wherein the first station and the second station communicate with one another using a spread spectrum radio link, the first station is operable in a normal mode for transmitting information relating to measurement events and in a power saving mode in which the first station periodically transmits a request signal to the second station for asking the second station if the first station should change to the normal mode, when the first station is operating in the power saving mode, and when the second station requires the first station to operate in the normal mode so that the first station can transmit information to the second station relating to measurement events, the second station responds to the request signal received from the first station by transmitting an instructing signal to the first station that instructs the first station to enter the normal mode, the first station continues to operate in the power saving mode, transmitting the request signal periodically, until it receives the instructing signal from the second station, in response to which the first station changes mode from the power saving mode to the normal mode, the first station periodically transmits a regular signal when operating in the normal mode, transmission of the request signals in the power saving mode and transmission of the regular signals in the normal mode allow the second station to maintain synchronisation with the first station, and a rate of transmission of the request signals in the power saving mode is slower than a rate of transmission of the regular signals in the normal mode.