| 摘要 |
PURPOSE:To easily diagnose a fault of a transmitting and receiving module without providing any additional equipment to transmitting and receiving modules and an antenna system which is used while they are arranged and mounted by diagnosing the fault from whether or not the transmitting and receiving module oscillates owing to a loop gain. CONSTITUTION:When the fault of the transmitting sand receiving module is diagnosed, a loop is formed of a transmission and reception system at the time of fault diagnosis and transmitting high-output and receiving low-noise amplifies 1 and 2 are placed in an operation and a nonoperation state at the same time respectively to decides whether or not the transmitting and receiving module has the fault from whether or not the receiving amplifier enters loop oscillation. The fault of the module can be diagnosed whether or not oscillation occurs in those four modes, and the oscillation can be confirmed by detecting a high-frequency signal radiated from an antenna 6, a high-frequency signal appearing at a feeding side (terminal A), and variation of a bias current due to the oscillation.
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