| 摘要 |
The present invention proposes a frequency offset cancellation apparatus which reduces the quantity of computations to cancel a frequency offset and decreases a processing time required for the computation. The frequency offset cancellation apparatus of the present invention changes the frequency of a received high frequency signal by a frequency converting circuit (1) and a local oscillator (2) to produce a base band signal, and converts it into a digital signal by an A/D converter (3). Subsequently, correlation value signals obtained by despread the digitized base band signal with spread code shifted from inputted base band signal with respect to time are inputted to a detecting circuit (5a to 5n). Respective detection circuits (5a to 5n) detect by multiplying the correlation value signals by the signals obtained by convenion into a conjugate complex form, which are preceded for one symbol. The detection signals from the detection circuits (5a to 5n) are combined by a combining circuit (6). The combined signal is inputted therefrom. A frequency offset detection circuit (7) compares the output signal inputted from the combining circuit (6) with a theoretical value of a known pilot signal portion whereby a frequency offset is detected. The frequency offset cancellation circuit (8) rotates the output signal from the combining circuit (6) reversely based on the value of the frequency offset. Thus, the frequency offset of the output signal from the combining circuit (6) is canceled by the frequency offset cancellation circuit (8) so that an output signal, the frequency offset of which is canceled, is provided. <IMAGE> |
