| 摘要 |
PURPOSE:To definitely and easily detect a carrier sense signal in an SSC receiver by calculating a square signal of a reception signal and detecting only a carrier of a spreaded spectrum signal from the square signal. CONSTITUTION:A waveform diagram depicts a spectrum of a reception signal A amplified by a high frequency amplifier section 1. A frequency fC indicates a center frequency of a desired SSC wave and f1-f3 represents narrow band signals of an undesired wave. The received signals are multiplied by a multiplier 2 to square them and a carrier being an SSC wave is reproduced independently of a spread code and the spectrum of the output of the multiplier 2 is as shown in figure (b). The signal is given to a band pass filter 3 whose center frequency is 2fC to extract only the carrier component of the SSC wave. The way is shown in figure (c). Broken lines in figure (e) represent a characteristic of the filter 3. The carrier of the extracted SSC is detected by a detection section 4 and a level of the detection signal is detected by a detection section 5 to obtain a carrier sense signal B. |
