| 摘要 |
PROBLEM TO BE SOLVED: To reduce an amount of filtering processing to provide a compact, lightweight, and low power modem.SOLUTION: A logarithmic transformation ROM1 part 200 virtually adds DC offset to a received signal and applies logarithmic transformation to the signal, and outputs a result to a tap delay line part 205. A logarithmic transformation ROM2 part 206 separates a filter coefficient into a sign bit, and logarithmically transformed mantissa information and index information, and outputs them, and adds them to output signals of respective tap data 201 to 204 at first adders 210 to 213. Inverse logarithmic conversion ROM3 parts 215 to 218 apply inverse logarithmic conversion to results of the first adders 210 to 213, subtract DC offset added at a filter input point by bit shifter/polarity control parts 220 to 223, an addition part 225, and a second adder 226, and obtain a final filter output.SELECTED DRAWING: Figure 21 |
