| 摘要 |
PURPOSE:To realize high speed FH changeover by generating a frequency signal different from a frequency hopping pattern of a Reed Solomon code or the like by means of a DDS system using a ROM table continuously while switching the signal for each chip period. CONSTITUTION:An angular velocity data omegai from an FH code generator 10 is added to a value already added which is stored in a register 14 at an adder 12 to obtain an angle data omegait. A sinusoidal data generated from a sinusoidal wave conversion ROM table 16 is converted into an analog sinusoidal wave signal by a D/A converter 18 and given to a low pass filter(LPF) 20. Phase distortion of a signal waveform of each chip frequency component is eliminated by using an SAE filter with an excellent group delay characteristic as a band pass filter 26 to minimize the waveform distortion for each chip frequency and to ensure the demodulation of the chip frequency at the receiver side. |
