| 摘要 |
PURPOSE:To reduce the effect of a narrow band interference wave and to improve the communication quality by converting an output of a correlation device into base band information and eliminating a frequency component of a specific range from the converted output. CONSTITUTION:An undesired component nonlinearly generated from a correlation device 12 is eliminated by using a filter 14 and a detector 15 applies square detection or envelope detection and the undesired harmonic wave is eliminated from the result at a low pass filter 16 and a signal subject to frequency shift to a base band is obtained from the high frequency correlation output. The spectral component in spurious variation mainly exists as frequency components from a DC to nearly 1/tau (tau is a gate delay time of a correlation device). Then a high pass filter 17 eliminates spectral components from DC to 1/tau. Even when a reception signal mixed with a narrow band interference wave is inputted to the correlation device and correlation spike is superimposed on the spurious wave, since the fluctuation in the spurious is suppressed, an error in the demodulation data is reduced. |
