| 摘要 |
<p>The unit for the transfer of binary data between a movable data medium (12) and a fixed station (11) comprises a first oscillating circuit (13) and the fixed station (11). This oscillating circuit comprises a capacitor (17). A field effect transistor (25) is switched in parallel with the capacitor by means of a switching pulse train. A second oscillating circuit (12) in the data medium (10) is inductively coupled with the first oscillating circuit (13) during at least a short time interval. In order to increase the gaps to be inductively overcome between the oscillating circuits (12, 13) of the data medium and the fixed station (11) without reducing the safety of operation during the data transmission, the oscillating circuit (13) is so arranged in the fixed station (11) that its resonance frequency is approximately equal to the frequency of the switching pulse train. The data transmission from the medium (10) to the fixed station (11) is carried out by amplitude modulation in the data medium (10) and by demodulation in the fixed station (11). The data transmission from the fixed station (11) to the data medium (10) is carried by frequency modulation and frequency demodulation, the frequency ratio being 2:1.</p> |
