| 摘要 |
PURPOSE:To easily implement the overall test and to easily discriminate a fault location by setting a frequency difference between a transmission intermediate frequency and a reception intermediate frequency equal to a frequency difference between a transmission frequency and a reception frequency. CONSTITUTION:A transmission frequency fT and a reception frequency fR are set while being parted by a difference frequency f1 and a transmission intermediate frequency f1T and a reception intermediate frequency f1R are set similarly while being parted by a difference frequency f1 similarly. In the case of conducting a radio line loopback test, an output signal 2 of a transmitter 1 is branched and inputted to a mixer 71. The mixer 71 receives a signal from an oscillator 70 generating a signal having the difference frequency f1 of the transmission frequency and the reception frequency and converts the output signal 2 into a signal 74 having the reception frequency. A switch 80 receives a reception signal 5 from an antenna or the converted signal 74, selects the converted signal 74 in the case of the loopback test and inputs it to a receiver 4. Thus, the test of the system passing through an intermediate frequency section 102, a high frequency section 101 of the transmitter 1, a high frequency section 104 and an intermediate frequency section 402 of the receiver 4 is conducted. |
