| 摘要 |
A radio receiver arranged to sample an input signal comprising a carrier signal modulated by a predetermined spreading sequence of pseudo-noise code symbols or chips that is stored in the receiver, the carrier signal frequency hopping between predetermined values in a predetermined sequence which is repeated cyclically and is stored in the receiver; the receiver being arranged to accumulate, over all the hops of the frequency hopping cycle, digital samples of the input signal correlated with the spreading sequence, and to perform a Fourier transformation of the accumulated digital samples to generate output data representative of data conveyed by the input signal and/or the time of receipt of the input signal; the receiver comprising a processor arranged to synchronise itself with the frequency hopping cycle and with the spreading sequence at each predetermined value of frequency, by repeating the correlation at different phases of the hopping sequence and of the spreading sequence such as to maximise the output data; wherein the correlation and accumulation are performed at a higher sampling rate over a high-resolution portion of one spreading sequence cycle than over the remainder of that spreading sequence cycle.
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