| 摘要 |
<p>A transmitter device (1-4) includes a rotational direction sensor (13) that generates a specific pattern signal when a corresponding tire (T1-T4) rotates. The pattern signal of the left tires (T1, T3) is different from the pattern signal of the right tires (T2, T4). A front reception antenna (21) is near the front tires (T1, T2). A rear reception antenna (22) is near the rear tires (T3, T4). A receiver (5) includes a switch circuit (23) that selectively connects the front reception antenna (21) or the rear reception antenna (22) to a controller (20). When one transmitter device transmits a radio signal, the controller (20) determines which transmitter device is the source of the radio signal in accordance with the level of the signals from the reception antennas (21, 22) and the pattern signal, which is included in the data transmitted by the transmitter device.</p> |
