| 摘要 |
PURPOSE:To obtain a radio call system existing in systems using the same frequency without mutual interference by arranging monitor receivers dispersedly and controlling the transmission of a radio call transmitter on the basis of the receiving states of the monitor receivers. CONSTITUTION:It is supposed that one of monitor receivers is set up on a position 106 and its electric field detecting level is set up to a level 104. When the 1st other system executes transmission, electric field intensity 117 is detected on the position 106 of the monitor receiver. Since the value 117 exceeds the level 104, a control circuit 6 does not give the permission of transmission to the transmitter 1. At the transmission of the 2nd other system, electric field strength shown at a point 127 is detected by the position 106. Since the value is less than the level shown by the short dashed line 104, the control circuit 106 gives the permission of transmission to the transmitter 1. In this case, the ratio of a required signal to an interference signal can be set up to a sufficiently high value even if the radio call receiver exists in any position of a service area 105. |
