| 摘要 |
PURPOSE:To obtain a wide and dynamic range as well as to eliminate the leak at the RF band by inserting the attenuator to the IF band at the preceding step of the mixer, and thus to ensure an easy and accurate measurement of the dynamic range and others for Smin and the receiver. CONSTITUTION:Part of the COHO signal featuring fequency fc of the transmitter is amplified 2 and then converted into the pulse signal through modulator 3 to be supplied to mixer 4 via attenuator 6. Thus, the pulse signal is mixed with the signal of frequency fL derived from STALO8 to turn to false fixed signal of frequency fL + fc. On the other hand, the false mobile target signal is obtained by supplying the signal of frequency fc + fd via switch 1. With insertion of attenuator 6 between modulator 3 and mixer 4, the output of mixer 4 can be controlled at the frequency IF band of COHO for the signal of the RF band. Accordingly, in case the very minute signal is required for measurement of Smin or the like, the output of the mixer turns to the attenuation signal by attenuating previously the level of COHO to a proper level. Thus, the signal which causes the leak as the fault can be eliminated. |
