| 摘要 |
The invention relates to a method and to a device for comparing two ground-stationed clocks (1 and 2) that are linked with respective ground stations (2 and 4) via a satellite communications link (6.1 and 6.2). Both stations emit signals (S1 and S2) in coherence with their respective local clocks. Said signals are converted at the satellite (9) in a transponder (7) using the satellite-based local oscillator (8) and are returned to the ground. Each ground station receives the respective own signals (E 1-1 and E 2-2) and those of the counter-station (E 1-2 and E 2-1). For the purpose of measurement, the carrier phase ( phi 1-1, phi 1-2, phi 2-1, phi 2-2) of the received signals is compared with the respective local clock and evaluated. The result of said evaluation are four independent measurements from which the unknown influences by the satellite-based local oscillator (8) and by the two different relative movements of the satellite with respect to the ground stations are eliminated. As a result, the frequency difference (5) of the clocks is determined.
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