| 摘要 |
PURPOSE: A scaling method of a decode input having a variable transfer rate and an apparatus thereof are provided to simplify interfacing without an internal RAM for a look-up table and with reduced SMTDATA register by sequentially receiving code symbols from a demodulator and directly scaling it through a simple bit operation when a decode decodes the code symbols transmitted in a different transfer rate for every frame by using a symbol repetition technique. CONSTITUTION: A complement format converter(51) of signed magnitude format/2 sequentially receives two code symbols(r1,r2) from a demodulator and converts the code symbols(r1,r2) in a signed magnitude format into a complement format of '2'. An MSB comparator(52) compares MSBs of the two code symbols as inputted, the complement format of '2', and outputs '0' to a multiplexer(59) if the MSBs are identical to each other or outputs '1' if the MSBs are not identical to each other. An adder(54) adds two input code symbols, the complement format of '2', and expresses it in a (n+1) bit. An LSB remover(55) removes an LSB from an output of the adder(54). The output of the LSB remover(55) is transmitted to an MSB inverter(57) and the multiplexer(59). The MSB inverter(57) inverts only the MSB of the output of the LSB remover(55) and outputs it to the multiplexer(59). If the output of the MSB comparator(52) is '0', the multiplexer(59) selects the output(56) of the LSB remover(55), while if the output(53) of the MSB comparator(52) is '1', the multiplexer(59) selects the output(58) of the MSB inverter. The output symbols(6) of the multiplexer(59) are expressed in a complemented format of '2'. That is, 2 symbol scaling unit sequentially receives two code symbols(r1,r2) from the demodulator and outputs one scaled code symbol. |
