Patent ID: 6925292

Claim:
An apparatus ( 10 ), comprising: a) a cellular module ( 11 ), responsive to a portion of a downlink frame signal conveying a cellular frame provided by a cellular communication system; and b) a main module ( 12 ), responsive to ranging signals from beacons ( 27 ) of a positioning system in which time is kept according to a predetermined time reference; the apparatus ( 10 ) characterized in that: the cellular module ( 11 ) provides a trigger signal indicating the arrival of the portion of the downlink frame signal, and is further responsive to a signal indicating information for relating the instant at which the trigger signal is provided to a time value according to the predetermined time reference; the apparatus ( 10 ) relates the instant at which the trigger signal is provided by the cellular module ( 11 ) to a time value according to the predetermined time reference; and the main module ( 12 ) uses the time value for synchronizing into ranging signals from beacons ( 27 ) of the positioning system; wherein the trigger signal is provided over a connection ( 29 ) between the cellular module ( 11 ) and the main module ( 12 ) so constructed that any delay between sending and receiving the trigger signal is either negligible or can be determined.