| 摘要 |
<p>Multipath fading simulator and method for use in the testing of microwave transmission and reception equipment. In the preferred method, the simulator is first independently calibrated for increments of notch position and notch depth using a variable frequency calibration tone. Then, with a modulated test signal input instead of the calibration tone, an appropriate sequence of notch positions and depths is played back under stored program control to generate the desired dynamically faded test signal. The simulator has two parallel signal paths (A, B) which include a phase-shifter (120) and a compensating attenuator (136). A feedback circuit (100, 122, 102, 126, 110, 132) is used to balance the signals in the two paths by adjusting the setting of the compensating attenuator (136) when calibrating for notch position; at which time such adjustments are recorded. In operation mode (when the test signal is input), the feedback circuit is disabled and the desired sets of compensating attenuator and phase-shifter adjustments are played back to generate the desired notch position. The desired notch depth can be generated by using series/parallel attenuator sets (804, 806; 814, 818) to vary the signal level contributed to the combined output by each path, or by coupling the signal in one or the other path to the combined output by a variable attenuator (200).</p> |
