| 摘要 |
There is provided a base-band filter for use in a transmitter of a DS-CDMA system. The filter includes data storage for storing a plurality of sample data which are generated by the input signal sequentially delayed for a predetermined time, an energy level detector for determining whether the energy level of the input signal is equal to a current energy level to detect the location value at which a energy level is varied, comparing the location value of a sample data with the detected location value to select one of the current energy level and the previous energy level, and outputting the selected energy level as the energy level for the sample data, a coefficient selector for selecting a filter coefficient for the each sample data corresponding to the energy level selected by the energy level selector, a sign converter for converting the sign of the coefficient selected in the coefficient selector according to each sample data value stored in the data storage, and an adder for adding all the outputs of the sign converter and outputting the sum. A result of the present invention is that the amount of hardware required to realize the digital filter can be remarkably reduced.
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