| 摘要 |
A service request system comprises a number of request units 5 located within a service area, a number of receivers 4, a location unit 3 and a display. The request unit 5 comprises a manual control and wireless radio transmitter and sends a radio request for service signal in response to operation of the manual control. A receiver receives a request for service signal and reports reception of the request for service signal and the relative position, relative to itself, of the request unit to the location unit. The location unit derives the location of the sending request unit within the service area from the report and relative position and shows this location on the display.
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