Implementation of Digital Quadrature Modulation.
MARK RESOURCES INC MARINA DEL REY CA
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Two basic methods of implementing digital quadrature modulation have been proposed. Although the multiplying DA implementation appears at first look to be simpler than the digital multiplier implementation, a more detailed analysis favors the digital multiplier implementation. The digital multiplier implementation is about 9,500 less expensive since the multiplier may be easily multiplexed over 8 range gates. It is impractical to multiplex the analog reference voltage in the multiplying DA implementation, and the required 4-quadrant multiplying DACs are more expensive than the simple DACs required for the digital multiplier implementation. Furthermore, the digital multiplying implementation may not be able to meet the performance requirements due to the slower setting time of multiplying DACs and the unknown capability of the multiplying DAC to follow the rapid changes of the reference voltage. It is thus recommended that the implementation of digital quadrature modulation be the digital multiplier method. Cost estimates for both methods of implementation are presented in Tables 1 and 2. The designs are for four channels of eight range gates each, including the interfacing to the array processor. The costs do not include conversion to 2s complement integers which might be accomplished in the array processor. Space requirement is 7 to 10 inches of 19 inch rack space for either implementation. Author
- Economics and Cost Analysis
- Electrical and Electronic Equipment