Patent ID: 8818406
Filing Date: 2014-08-26
Classification: G01S,H04L,H04W

Abstract:
1. Method for clocking involving at least a first device, a second device and a third device in a fixed positional relationship, the method comprising: at least the first device transmitting a sequence of unique signals comprising at least a first and a second signal having a unique identification; measuring the reception times of the uniquely identified signals at at least the second and third device with a respective second and third local clock of the second and third devices, at least the second and third device associating a reception time of the second and third device to respectively the first and the second signal upon reception thereof, leading to at least two value pairs of local clocks of the second and third device; based on the value pairs of local clocks, modeling a time function of a dependency of the second and third local clock over time as a first model curve; at an arbitrary point in time receiving a user signal from a user device at the second and third device and associating a reception time measured by the respective second and third local clock of the second and third device to the user signal upon its reception, leading to a user value pair of local clocks of the second and third device; calculating a reference time difference of arrival RTDOA for a signal from the first device received at the second and third device from the fixed positional relationship, based on the respective distance between the first and the second device and the first and the third device and the known signal propagation speed; calculating a user time difference of arrival UTDOA from the user value pair; at the arbitrary point in time determining a value from the first model curve and based on this value calculating a determined time difference of arrival DTDOA; relating the RTDOA to the DTDOA to determine a current correction factor; and for clocking using the current correction factor to correct the UTDOA.