| 摘要 |
PURPOSE:To obtain an excellent spread spectrum communication system with a simple circuit by applying an offset pattern voltage predetermined by a polynomial to the VCO of a PLL at a system reception side so as to prevent the loss of locking due to a narrow lock range. CONSTITUTION:A frequency hopping signal is fed to a D/A converter 43, the converted signal is subjected to waveform shaping by a hold circuit 44 and fed to the VCO 45. The VCO 45 is subjected to frequency modulation from the frequency hopping signal from the circuit 44, a carrier is subjected to frequency hopping, that is, the carrier where the spectrum is spread is generated. The carrier is divided into two system for PSK modulation; one is fed to a phase shifter 46, where the phase is changed by 180 deg., the result is selected by a switch 47 and a PSK signal is generated. On the other hand, the interleaved signal is scrambled by using a PN signal by the 10-order polynomial. The scrambled signal and a frame synchronous pattern signal are selected by a switch 41 and fed to a PSk modulator. |
