| 摘要 |
The present invention describes a method and a system to compute the time (t1) and the position (P1) of a receiver (102, 805, 901) based on satellite radiofrequency signals without accurate, a priori time or position information and without the need for demodulating data from the signals received by the satellites (103, 800). In particular, the present invention computes the receiver time (t1) and position (P1) by estimating the time offset between the actual time (t1) and an initial time (t0), which can be defined arbitrarily and even have an error of hours or days. The estimation of this time offset is performed by updating Doppler estimations (D(t0), D(t1)) between different times using Doppler change rates. |
| 主权项 |
1. A method for calculating an actual time (t1) and an actual position (P1) of a radionavigation receiver (102, 805, 901) by using satellite radiofrequency signals, characterized in that the method comprises:
providing an initial receiver time (t0), an initial receiver position (P0) and satellite position data; receiving said signals by said receiver (102, 805, 901) and computing from said received signals Doppler measurements between said satellites (103, 800) and said receiver (102, 805, 901); estimating Doppler values (D(t0)) and Doppler change rates between said satellites (103, 800) and said receiver (102, 805, 901) at the initial receiver time (t0) and at the initial receiver position (P0) by means of said satellite position data; computing Doppler values (D(t1)) between said satellites (103, 800) and said receiver (102, 805, 901) at the actual receiver time (t1); calculating a time difference between the actual receiver time (t1) and the initial receiver time (t0) by computing a subtraction of the Doppler values (D(t0)) at the initial receiver time (t0) from Doppler values (D(t1)) at the actual receiver time (t1) and dividing said subtraction by the Doppler change rates; and calculating the actual receiver position (P1) by means of the calculated actual receiver time (t1). |
