AUTOMATIC ACTIVATION OF SPEED MEASUREMENT IN MOBILE DEVICE BASED ON AVAILABLE MOTION

摘要

A system and method for speed measurement of a mobile device (300), using a speed sensor (460) such as a satellite navigation system (460) or an accelerometer, does not need such speed sensor (460) to be continually activated. The system and method make use of a monitor (471) for monitoring at least one motion indicium for indicating that the speed of the mobile device (300) is above an initial threshold (112), including but not limited to: monitoring the Doppler shift measurements of a timing signal; monitoring the timing advance of a cellular radio signal; monitoring the number of base stations (511) visible to the mobile device (300); monitoring the frequency of base station handover, however determined; monitoring the level crossings and/or the autocorrelation of an RSSI signal; and/or triangulation of the position of the mobile device (300). When the monitor (471) determines that the mobile device (300) may be travelling in excess of a threshold speed (112), a speed sensor (460) is activated to confirm the indication. If the speed sensor (460) determines that the mobile device (300) is travelling at a speed below a second threshold (171), the speed sensor (460) is deactivated.