Wednesday, 30 July 2008

?????????? ????????????????? ??????? (?)

???????????????? texual imformation ?????????????? formatting ??????????????? ??????????????
Texual messages(texual data) ?? ??????? ????????????????????? alphanumeric characters ??? sequence ???????? ????????? ???????????????? transmitted ????????????? ????????? character ??? sequence of bits ???? encoded ?????????? ? ???????????? bit stream or baseband signal ???????????? ? finite symbol set ???????????? M = 2^k ??? k ?bits ??? ???????????? ?????????????? ???????????????? symbols ??????????????? ???????????????????? ?????? ??????? ??????????????????????? M symbol set size ??????? ??????? M- array system ???????????? ? ??????????????????????????? ??????????? k ??? M ??? ????????? ?????????????? k=1 ??????????? M=2 ???????????? ????????? ???????? ????????????????? ???? ??????????????? waveform ??????????????? ???????????? modulator ?? 1 ?????????????????? waveforms 2 ???????????? ?????????????????????????? waveform ?????? 0 ??? ????????????? k= 2 ??????????? M=4 ???????????? ????????? quateranry (????) 4-ary ????????????? symbol time ???????? modulator ?? waveforms ???????? symbol ??? ?????????????? ???????? ?????????????? ?? bits ??? sequence ??? ???????????????????????? ASCII code ?????????????????????? texual message ??? bit sequence ?????? ??????????? ??? ??? ??????????? ????????????????? M ? ???????????????? ????????????? ?????????????? binary digits ?????????????? ????????? 8-ary digits ??? ??????????? ??????????? ????????????? k=logM(log ??? base ? 2 ??) ??????????? k ?????????? ????????? k ????????? bit ?????????????? ????????????????????????????? ?????????????



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Texual message ??? THINK ?????????? ?????????? ????????? ?????????????????
6-bit ASCII character coding ??? ??????? ? (??????? ASCII table ??????????????????) T ?????? ????????????? ? bit ???????? 6 ??????????? THINK ? 5 ??????????? 6*5=30 ????? ????????????? THINK ?????? ??????????? ??????????????30 ??????????? ????????? k ??? M ?????????? ???????????????????? M ??? 8-ary digit ????????????????? k=logM(log ??? base ????? 2 ??) ?? k ????????? 3 ????????????????? ?????? ????? 30 ??? k=3 ?????????????????? 10 ?????? ??????? ???? ?? ???? transmitted ???????? 10 octal symbols ??? ????????????????? transmitter ??? ?????????????????? symbols ?????? ??????????????? waveforms s_i(t) ( i=1,?..,8 ) 8 ?? ??? ??? (set) ???????? symbol time ?????????????? ???? ?????????????????? symbols ?????? symbol ???????? transmit ??????????????? ?????? ?????????? ??? THINK ?????? message ??? ?????????????? 8-ary modulating systme ?????????? waveforms ?? ????????????????????
????? ???? ??????
Texual message ? HOW ?????????
6 bit ASCII code ??????????????? character ??????????? bit sequence ??? ???????????? ?
4-ary digits ?????????????????????? ???????? k ????????? k=logM(base ????? 2)= 2 ????????? ? symbols ?????? 9 ????????? ???? symbol 9 ???? transmitted ??????? quateranry symbols ????????????? ???? transmitter ??? ?????????????????? symbols ?????? ??????????????? waveforms s_i(t) ( i=1,?..,4 ) 8 ?? ??? ??? (set) ???????? symbol time ?????????????? ???? ?????????????????? symbols ?????? symbol ???????? transmit ??????????????? ?????? ?????????? ??? HOW ?????? message ??? ?????????????? 4-ary modulating system ?????????? waveforms 9 ????????????????????



?? ????? ?????????? LOVE ?????? ???????? ??? ????????????????? ????


????????? ????????? log ??? base ????????? ???????????? ????????????????????? ??????????????

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