| 摘要 |
A method for estimating an unwanted component (noise) that a receiver introduces into a received signal (201, Figure 2) at a known frequency, the method comprising applying a frequency offset to a signal 102, which comprises a wanted component at the known frequency, to form an offset signal having a frequency spectrum (302, Figure 3) in which the wanted component is not positioned at the known frequency, processing the offset signal in the receiver 103 and estimating a component positioned at the known frequency in the frequency spectrum of the processed signal 104. The estimated component will correspond to the unwanted component, for example at DC, introduced by processing the signal at the receiver. This estimated unwanted component can therefore be estimated and removed, i.e. subtracted, from the processed received signal 105. The method in one embodiment therefore provides a DC offset estimation and compensation arrangement. The frequency offset may be applied at the receiver or at the transmitter. The signal may comprise a synchronization portion (202, Figure 2) consisting of a series (206, Figure 2) of identical repeated blocks (207, Figure 2) and in one embodiment only the synchronization portion is frequency offset. The synchronization portion may have a frequency spectrum (301, Figure 3) comprising a plurality of equally spaced peaks and the frequency offset may be set to be equal to an odd-multiple half of the spacing between two of the peaks. The frequency offset may be reversed once the estimated unwanted component has been removed from the signal. The unwanted component introduced by the receiver may be due to a number of factors such as noise or offset introduced from amplification, mixing or filtering etc. stages. |
