| 摘要 |
METHOD AND APPARATUS FOR AUTORANGING, QUADRATURE SIGNAL GENERATION, DIGITAL PHASE REFERENCE AND CALIBRATION IN A HIGH SPEED RF MEASUREMENT RECEIVER Improved autoranging, calibration, and a complex signal detection circuits for an intermediate frequency (IF) stage in a radio frequency (RF) measurement receiver (8). An improved autoranging circuit (75) sets a gain stage of a selectively variable gain amplifier (72) prior to each data acquisition cycle, to provide for wide-dynamic range and rapid time domain response. An improved complex signal detection circuit (80) for generating an inphase (i) and quadrature phase (Q) signal from an input IF signal in a signal channel (38a) and a reference channel (38b) is constructed with a novel commutating demodulator circuit (12a, 12b). Calibration is effected with an improved digital phase reference method and apparatus wherein effective 90.degree. phase shifts are digitally generated by shifting the generation sequence of timing signals for the complex signal detection circuit (80) instead of phase shifting a known calibration signal, obviating the need for precision phase shifters, Dopler frequency generators, or Fourier transforms to obtain correction components for the optimum detection of complex signals.
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