| 摘要 |
PURPOSE:To achieve a highly accurate signal detection with a simple circuit configuration by receiving an information signal and a direction discrimination signal as a digital signal in a communication system between a ground station and a vehicle for performing information communication by radio between the ground station and the vehicle. CONSTITUTION:A reference frequency 1 and an information signal 8 or a direction discrimination signal 6 are given to a modulator 2. The modulator 2 uses the reference frequency 1 as a carrier and modulates it by the information signal 8 or the direction discrimination signal 6. The information signal 8 and the direction discrimination signal 6 are given to the modulator 2 by a switch 7 selectively. Since the information signal and the direction discrimination signal are transmitted alternately, no sub-modulation due to AM modulation is needed and a circuit configuration can be simplified and at the same time a highly accurate signal detection can be made. |
