| 摘要 |
A unique system for efficiently implementing filtered, phase shifted channels is disclosed. Instead of using separate transmit shaping filters for each channel, and modulating the filtered signals with phase-shifted carrier and one might suppose, the system phase rotates the signals for each channel and modulates such phase rotated signals with a single carrier. In addition, the system decomposes the phase rotations into 90° pre-filter portions and a post-filter portion of, for example, 45°. In an 8 channel system, such as proposed in the IS-95B standard, the channels are divided into two groups and the 90° phase rotations for each group are done at the input of the transmit shaping filters. A 45° phase rotation is then done for one of the groups at the output of the transmit shaping filter. Significantly, no multiplication is required.
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