| 摘要 |
PURPOSE:To measure transmission characteristics between transmitter and receivers easily and accurately by switching the service channel signal of a digital radio equipment to a link analyzer signal, and imposing frequency modulation upon a high-frequency carrier and sending out the resulting signal. CONSTITUTION:The service channel SC signal is inputted to an FM modulator 3 for composite modulation through an amplifier 1, LPF2, and switch circuit 6 and slight frequency modulation is imposed there upon the carrier by the SC signal to input the resulting signal to a PSK modulating circuit 4. The circuit 4 varies the phase of the FM-modulated carrier by PCM signals from terminals In1 and In2 and transmits the output through a BPF5. When the transmission characteristics of the radio equipment are measured, the circuit 6 performs switching to a terminal TMIn for transmission characteristic measurement from a link analyzer 7. The analyzer 7 sweeps the output signal of the circuit 3 over a wide range. The output of a transmitter Tx is transmitted to a receiver Rx through a radio circuit and inputted to the analyzer 7 to measure the total transmission characteristics of the radio equipment. |
