| 摘要 |
PURPOSE:To prevent the malfunction due to radio interference by interrupting a frequency modulated wave for a random time at every prescribed cycle by a frequency change interrupting means and taking out a beat signal between a part of a received wave and that of transmitted wave through an LPF and subjecting this beat signal to signal processing. CONSTITUTION:Though a transmitting part 1 transmits the frequency modulated wave changing the frequency as prescribed, the wave is interrupted for a random time at every prescribed cycle by a frequency change interrupting means 2. The beat signal between a part of the received wave and that of the transmitted wave is detected by a receiving part 3 and is allowed to pass through an LPF 4, and only the beat signal due to disturbing waves is attenuated to take out the beat signal. The beat frequency is counted at every prescribed time by a beat frequency counter 5, and the difference between current and preceding beat frequencies is obtained by a beat frequency change detecting part 6. When this difference exceeds a certain threshold, a signal indicating the influence of a disturbing wave is outputted. As the result, the malfunction due to radio interference is prevented by signal processing. |
