| 摘要 |
PURPOSE:To always estimate the present position of a portable radio equipment by applying logical decision and comparison decision of plural electric fields based on a received electric field by a base station in a service area and of a receiver. CONSTITUTION:A portable radio equipment is so constituted that the radiation of a radiow wave is automatically repeated at a prescribed interval through a call channel when the electric field is less than a prescribed reception electric field level. In measuring the quantity of noise of the channel, the electric field level of the carrier is measured and the location of the transmitted portable radio equipment is estimated. The output of the noise level measurement of a call channel of systems A-D and reception exclusive stations R1-R7 obtained in such a way is fed to a level comparator 40 and only the high-order 3-level is selected and fed to a logic circuit. A logic circuit 41 decides at which of out-service areas the radio equipment exists and the result is controlled by a CPU 42 together with the output of a PID detector 35 and the result is inputted to a display device 43. Thus, the present position of persons engaging in the work is displayed. |
