| 摘要 |
PURPOSE:To eliminate an interface by a relay between an analog circuit and a digital circuit by digitizing a series of signal processes. CONSTITUTION:When a power source 29 is energized, the frequency of 68kHz of a signal 68 is stored in a frequency memory circuit 27. When a vehicular element 6 on a train and a ground element becomes a coupling relationship, the oscillating frequency of a feedback amplifier 7A is converted from 60kHz to 81kHz, and the output SL1 of a selector 24 is varied from 60kHz to 81kHz. Thus, the output LP2 of a low pass filter 25 becomes zero, and a frequency counter 26 counts the output frequency of 81kHz of the selector 24. When the element 6 passes over the ground element, the oscillating frequency of the amplifier 7A returns to 60kHz. In this manner, the output LP2 of the low pass filter 25 rises, and the frequency value of 81kHz counted by the counter 26 is stored in the memory circuit 27. |
