| 摘要 |
PURPOSE:To obtain a correlation pulse with high S/N by inputting a spread spectrum signal to a matching filter with very high selectivity and providing an automatic gain control amplifier and a high gain amplifier to the output side of the matching filter. CONSTITUTION:A spread spectrum signal is inputted to a fixed gain RF(radio frequency) amplifier 23, where the signal is amplified and inputted to a mixer 24. A local signal is inputted to the mixer 24 from a local oscillator 25, and the signals are mixed and the spread spectrum signal is converted into an intermediate frequency. The intermediate frequency is inputted to a matching filter 26, where the signal is converted into a correlation detection signal, amplified by a high gain amplifier 27, and detected by an envelope detector 28 and converted into a correlation pulse. The correlation pulse from the envelope detector 28 is amplified by an automatic gain amplifier 29 and further amplified by a high gain amplifier 30 and fed to comparators 31, 32 and a comparator 33 being a component of the detection means respectively. Thus, the correlation pulse with high S/N is obtained. |
