| 摘要 |
PURPOSE:To provide a spread spectrum(SS) receiver which is simply constituted and can provide signals with satisfactory C/N. CONSTITUTION:The output of a BPF 22 is impressed to a circuit composed of rectifiers 26 and 27 and bias resistors 28 and 29 for the rectifiers, a positive half wave f1 and a negative half wave f2 are provided, second modulated waves at frequencies 2f1 and 2f2 are provided by synthesizing those half waves at a differential amplifier 30, and those second modulated waves are impressed to a cyclic filter composed of adder circuits 31 and 32, delay lines 33 and 34 and gain control circuits 35 and 36. Those outputs pass respectively through gain control circuits 37 and 38 and limiters 39 and 40 and demodulated by FM demodulators 41 and 42, a difference is provided by a differential amplifier 43 and passes through a shaping circuit 44, and a data output signal 45 is provided. Loop transmission times tau1 and tau2 of respective cyclic filters are set to tau1=1/2f1 and tau2=1/2f2. Loop gains K1 and K2 are enlarged as much as possible although on the condition of K1<1 and K2<1 at the frequencies 2f1 and 2f2. |
