Digital Quadrature Modulation.
MARK RESOURCES INC MARINA DEL REY CA
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Two methods of modulation, analog quadrature and amplitude-phase, are being considered for the near term implementation of clutter and extended targets. Due to the practical non-linearities and imbalances of the physical devices implementing these modulation methods a compensation method is required to achieve acceptable performance. Rather complicated compensation tables are required, a calibration procedure is required to determine the table values, and the stability of the compensation is in question due to its sensitivity on possible drifts of the physical device characteristics. The compensation must be performed in real time and requires a considerable amount of digital processing. This report considers an alternate method of digitally processing the modulation signals to obtain a real signal which is then mixed up to the desired frequency. This mixing is the only operation subject to practical non-linearities and drifts. Such a simple mixing does not have the extreme sensitivity to mixer imbalances exhibited by analog quadrature modulation. It is anticipated that this mixing will require no compensation however, should compensation be required it would be simple since only one signal no cross-coupling need by compensated. Author
- Electrical and Electronic Equipment