| 摘要 |
Device for correcting for the Doppler shift due to the relay satellite in a digital radio telephony link. The base station creates a FCCHD synchronisation burst which replaces the usual FCCH synchronisation burst which is of fixed frequency. The instantaneous frequency (fi) varies, for this FCCHd burst, according to a known law, for example a sum of two linear laws for the duration of the burst, with different coefficients (8, 9, Figure 3). The start time ( tau ) of this FCCHD burst is calculated by a rule of three. The Doppler shift (d) is calculated by elimination of the other terms from the received signal and spectral analysis. The correction for the Doppler shift is performed by correction of the frequency of the demodulation Local Oscillator. <IMAGE>
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