| 摘要 |
PURPOSE:To provide the radio transmitter suitable for the frequency hopping method by which a spurious signal and a phase modulation signal with less phase noise are transmitted. CONSTITUTION:A DDS1 produced a VHF band frequency hopping signal S3 and a phase locked loop oscillator 2 produces a UHF band signal S4 resulting from decreasing the spurious signal of the signal S3. The signal S4 is used as a reference signal of the phase locked loop oscillator 3 whose voltage controlled oscillator 33 transmit a phase modulation signal S5. The phase locked loop oscillator 3 includes a modulator 34 using a modulation signal S6 to apply phase modulation to a frequency divided signal S34 of the phase modulation signal S5(S35). An output S33 of the modulator 34 is used as a comparison signal of a phase comparator 31. Since the phase locked loop oscillator 3 has a phase locked loop band sufficiently wider than the signal band of the modulation signal S6, a phase modulation signal S5 sufficiently following up the modulation signal S6 is not only produced but phase noise in the phase modulation signal due to the voltage controlled oscillator 33 is suppressed. |
