| 摘要 |
A method is described of determining a frequency offset/error 409, for example, between a carrier frequency of a transmitter and receiver 402. A method for determining a frequency error embodied in a series of values, each comprising a phase component, by a change in those phase components across the series, comprising: processing each of two or more selected values with another value in the series, each other value being spaced from its respective selected value by a first spacing, to generate processed values that all comprise substantially the same phase component 405; combining the processed values to generate a combined value that comprises substantially the same phase component as the processed values; repeating the processing and combining with the same selected values but a second spacing, different from the first spacing, to generate a combined value comprising a different phase component from the combined value generated using the first spacing, reflecting the frequency error; and determining the frequency error in dependence on the combined values generated using the first and second spacings. Each value in the series may represent a comparison between a received signal and a known sequence, such as a synchronization word of a preamble. The comparison may be performed by selecting a section of the received signal, performing a correlation operation between the selected section and the known sequence 403, and designating the result of that correlation as a value in the series. The processing of each of the selected values with respective other values may comprise a correlation operation. Each of the series of values comprises a wanted component and noise, the method comprising processing the series of values and combining the processed values such that the wanted components are coherently combined and the noise is incoherently combined to improve the signal to noise ratio of the combined values. The frequency error may be determined in dependence on the slope of a straight line 408 representing the linear relationship of phase changes across the combined values. |
