7 7 1 pcm 7 2 7 3 7 4 7 5 7 6 dpcm 7 7 7 8 7 8
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第 7 章模拟信号的数字传输 7.1 PCM 基本概念 7.2 模拟信号的抽样 7.3 模拟脉冲调制 7.4 抽样信号的量化 7.5 脉冲编码调制 PowerPoint PPT Presentation


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第 7 章模拟信号的数字传输 7.1 PCM 基本概念 7.2 模拟信号的抽样 7.3 模拟脉冲调制 7.4 抽样信号的量化 7.5 脉冲编码调制 7.6 差分脉冲编码调制( DPCM ) 7.7 增量调制 7.8 时分复用和复接 7.8 时分复用和复接. 7.1 PCM 基本概念.

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第 7 章模拟信号的数字传输 7.1 PCM 基本概念 7.2 模拟信号的抽样 7.3 模拟脉冲调制 7.4 抽样信号的量化 7.5 脉冲编码调制

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7 7 1 pcm 7 2 7 3 7 4 7 5 7 6 dpcm 7 7 7 8 7 8

7

7.1 PCM

7.2

7.3

7.4

7.5

7.6 DPCM

7.7

7.8 7.8


7 1 pcm

7.1 PCM

  • A/DD/AA/DD/A


7 7 1 pcm 7 2 7 3 7 4 7 5

  • A/D(PCM,Pulse Code Modulation


7 7 1 pcm 7 2 7 3 7 4 7 5

  • PCMAlce Reeres19371946PCMBell1962PCM2070PCMPCM


7 7 1 pcm 7 2 7 3 7 4 7 5

t

011

100

100

011

011

100

100

  • 3


7 7 1 pcm 7 2 7 3 7 4 7 5

  • 7.2

    • 7.2.1

      • m(t)< fHT 1/2fHm(t)

        fHm(t) T(t)Tfs = 1/TTms(t) = m(kT)


7 7 1 pcm 7 2 7 3 7 4 7 5

m(t)

(a)

T(t)

0

T

-3T

-2T

-T

2T

3T

(c)

ms(t)

(e)


7 7 1 pcm 7 2 7 3 7 4 7 5


7 7 1 pcm 7 2 7 3 7 4 7 5

  • Ys()F()s2HYs()HYs()F()f(t)s2HYs()F()F()


7 7 1 pcm 7 2 7 3 7 4 7 5


7 7 1 pcm 7 2 7 3 7 4 7 5

M(f)(f)Ms(f)m(t)T(t)ms(t)m(t)T(t)M(f)(f)ms(t)Ms(f)

(f)

Ms(f)


7 7 1 pcm 7 2 7 3 7 4 7 5

M(f - nfs)M(f)nfsMs(f)fsM(f)


7 7 1 pcm 7 2 7 3 7 4 7 5

|M(f)|

f

(f)

-2/T

0

-1/T

1/T

2/T

-fH

fH

|Ms(f)|

fs

fs

f

-fH

fH

0

f


7 7 1 pcm 7 2 7 3 7 4 7 5

m(t)fHfs 2fHMs(f)M(f)Ms(f)m(t)M(f)

fsfH2fH


7 7 1 pcm 7 2 7 3 7 4 7 5

fs 2fHfH

fs2fH

3400 Hz8000 Hz


7 7 1 pcm 7 2 7 3 7 4 7 5

7.2.2

(0, fH)fs2fHfLfHfs0~fLfs


7 7 1 pcm 7 2 7 3 7 4 7 5

f

-fH

-fL

fL

fH

0

fLfH

fLfHB = fHfLfs

B

n (fH / B)n =12

k (fH / B)0 < k < 1

fsfL


7 7 1 pcm 7 2 7 3 7 4 7 5

fLfHB0 fL < BBfH < 2Bn = 1fs = 2B(1 + k)k01fs2B4BfLBfH2Bn = 2k0fs = 2Bfs4B2BB fL < 2B2BfH < 3Bn = 2fs = 2B(1 + k/2)k01fs2B3BfL2BfH3Bn = 3k0fs = 2Bfs3B2B


7 7 1 pcm 7 2 7 3 7 4 7 5

fL = 0fs2BfLfs2BfLfHBfs2B

fs


7 7 1 pcm 7 2 7 3 7 4 7 5


7 7 1 pcm 7 2 7 3 7 4 7 5

fHBfLfLBfLB2BfH1/(2fH)fH


7 7 1 pcm 7 2 7 3 7 4 7 5

7.3

m(t) m(t)(PAM)(PDM)(PPM)


7 7 1 pcm 7 2 7 3 7 4 7 5

PAM PDM PPM


7 7 1 pcm 7 2 7 3 7 4 7 5

(PAM) ms(t)PAM


7 7 1 pcm 7 2 7 3 7 4 7 5

  • PAM

    • PAM

      m(t)M(f)s(t)s(t)TS(f)Ams(t)m(t)s(t)

      ms(t)

      sinc(nfH) = sin(nfH) / (nfH)


7 7 1 pcm 7 2 7 3 7 4 7 5

m(t)

M(f)

t

0

-fH

fH

f

(a)

(b)

|S(f)|

s(t)

f

fs

0

-T

T

2T

3T

-3T

-2T

-1/T

0

1/T

f

(c)

(d)

ms(t)

t

(e)

-fH

(f)

fs

A

  • PAM


7 7 1 pcm 7 2 7 3 7 4 7 5

MH(f)

mH(t)

ms(t)

H(f)

m(t)

Ms(f )

T(t)

s(t)T (1/2fH)fs 2fHfH

    • PAMms(t)PAMPAM


7 7 1 pcm 7 2 7 3 7 4 7 5

t

  • H(f)MH(f)

    Ms(f)


7 7 1 pcm 7 2 7 3 7 4 7 5

MH(f)Ms(f)H(f)1/H(f)


7 7 1 pcm 7 2 7 3 7 4 7 5

7.4

m(kT)N, NM=2NM


7 7 1 pcm 7 2 7 3 7 4 7 5

  • 7.4.1

    • m(kT)TkNNM = 2NMMM


7 7 1 pcm 7 2 7 3 7 4 7 5

q6

m5

q5

m4

m(6T)

mq(6T)

q4

t

m3

T

2T

3T

4T

5T

6T

7T

q3

m2

q2

m1

q1

m(t)

  • MM


7 7 1 pcm 7 2 7 3 7 4 7 5

mq(kT)

m(kT)

  • m(kT)mq(kT)q1, q2,,qi, , q66m1, m2, ,mi, , m5

    m(kT)

    • m(kT)mq(kT)


7 7 1 pcm 7 2 7 3 7 4 7 5

i = 0, 1, , M

  • 7.4.2

    • abM

      qi


7 7 1 pcm 7 2 7 3 7 4 7 5

  • Nq

    mkm(kT)mqmq(kT)f(mk)mkEM

    mk

    mk


7 7 1 pcm 7 2 7 3 7 4 7 5

  • 1M[-a, a]


7 7 1 pcm 7 2 7 3 7 4 7 5

dB

M


7 7 1 pcm 7 2 7 3 7 4 7 5

  • 7.4.3

  • xy

    • MvNq


  • 7 7 1 pcm 7 2 7 3 7 4 7 5

      • vv

      • xyy = f(x)

      • y

        x

        x


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    (ITU)A 1315A1315


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • A

      • A

        x

        y

        A

        A yxyx


    7 7 1 pcm 7 2 7 3 7 4 7 5

    y1

    • A

      obobAb(x1, y1)

      1/A, Ax1/(1+lnA)

      A

      A

      A87.6


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 13 A

      • A13A


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • x0181/2181/41/271/81/4601/1281y 88(x, y)12


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 3

    • 112

      312

      14

      1313


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 15

      AA87.6

      1161613

      213Ax1/2i (i = 0, 1, 2, , 7)

      Ax = 1/2iy = 1 i/8


    7 7 1 pcm 7 2 7 3 7 4 7 5

    A

    x = 0yy = 0x = 1/28x = 0y = 0x = 1y = 1

    x = 0y = 0x = 1y = 1(x < 1/128)255


    7 7 1 pcm 7 2 7 3 7 4 7 5

    15Ay018x


    7 7 1 pcm 7 2 7 3 7 4 7 5

    8

    1515


    7 7 1 pcm 7 2 7 3 7 4 7 5

    15


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    15 A132A A

    A

    1513AA87.6A94.18A


    7 7 1 pcm 7 2 7 3 7 4 7 5

    7.5

    m(t)M128256(PCM)M


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 7.5.1PCM

      • 3.153.965.006.386.806.42345676(quantized value)011100101110111110

      • 3.153.965.006.386.806.42345676011100101110111110


    7 7 1 pcm 7 2 7 3 7 4 7 5

    7

    6.42

    6.38

    6.80

    6

    6

    5.00

    5

    3.96

    4

    3

    3.15

    011 100 101 110 111 110


    7 7 1 pcm 7 2 7 3 7 4 7 5

    PCM

    (b)

    PCM

    (a)

    • PCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    Is>Iw , ci=1

    Is< Iw , ci= 0

    Is

    c1, c2, c3

    Iw

        • 307.53c1c2c3

        • IsIw1IwIw3Iw3c1c2c3807


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • -0.5+7.5

    • c1Iw=3.5Is < 3.5c1 = 0Is> 3.5c1 = 1c1

    • c1c1 = 0Iw = 1.5c1 = 1Iw = 5.5Is < Iwc2 = 0Is > Iwc2 = 1c2

    • c1c2c1c2 = 0 0Iw = 0.5c1c2 = 1 0Iw = 4.5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    7.5.2

    PCMMN 8PCM

    PCM416


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    2

    (an-1, an-2, , a1, a0)

    D=an-12n-1+an-22n-2++a121+a020

    10


    7 7 1 pcm 7 2 7 3 7 4 7 5

    11110111 157815 10000000 81


    7 7 1 pcm 7 2 7 3 7 4 7 5

    1


    7 7 1 pcm 7 2 7 3 7 4 7 5

      • 138c1724(c2c3c4)384(c5 ~ c8)1616727 128


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 12x1/12816(1/128) (1/16) = 1/2048,(1/2048)18x1/2161/321/2048117

    • 8000 Hz64 kb/s


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 7.5.3


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 138c1c8c1

      • c1

      • 7/11711


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • -1+140961/20481+127013A

      8c1c2c3c4c5c6c7c8

      1) c1+1270c1 = 1

      2) c2c3c4c2128Iw1281270c21

      c21c3512Iw512c31


    7 7 1 pcm 7 2 7 3 7 4 7 5

    c2c311c4Iw10241270c41

    c2c3c41118

    3) c5c6c7 c8168

    c51078Iw = 1536Is = 1270c5=0c634Iw = 1280Is < Iwc60c7Iw = 1152Is > Iwc7=1c8Iw = 1216Is > Iwc8=1


    7 7 1 pcm 7 2 7 3 7 4 7 5

    1024

    1152

    1280

    1536

    2048

    1216

    1270

    0

    1

    2

    3

    4

    5

    6

    7

    8

    9

    10

    11

    12

    13

    14

    15

    8c1c2c3c4c5c6c7c81111001183(1280-1216)/2 = 12481270 1248 = 22

    12481110011100000


    7 7 1 pcm 7 2 7 3 7 4 7 5

      • c7Iwc8


    7 7 1 pcm 7 2 7 3 7 4 7 5

    c2 ~ c8

    c1

    7/11

    • c81248c1


    7 7 1 pcm 7 2 7 3 7 4 7 5

    7.5.4 PCM

    PCM

    PCM

    =m(t)+nq(t)+ne(t)

    m(t)nq(t)Nqne(t)Ne


    7 7 1 pcm 7 2 7 3 7 4 7 5

    NMM=2N

    PCMNNPCMB=NfH

    PCMB


    7 7 1 pcm 7 2 7 3 7 4 7 5

    PCM10 01PCM PePCM11


    7 7 1 pcm 7 2 7 3 7 4 7 5

    Pe=10-481P1=8Pe=1/125012502P2=C28Pe=2.810-7P2P11

    N 20, 21, 22, 2i-1 , 2N-1i(2i-1) (2i-1) 2Pe


    7 7 1 pcm 7 2 7 3 7 4 7 5

    Ne=En2e(t)=Pe (2i-1)2=2Pe 2Pe

    m(t)-a, a 6 - 1

    So=Em2(t)= dx= M2= 22N

    6.3 - 286.3 - 29, PCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    PCM

    4Pe22N>>1Pe4Pe22N<<1 PePe


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 7.6 DPCM

      • 7.6.1


    7 7 1 pcm 7 2 7 3 7 4 7 5

    mk

    ek

    m(t)

    rk

    mk*

    mk

    (b)

    (a)

    rk

    mk*

    • 1DPCM

    • ek = rk

      mk*mkmk*mk


    7 7 1 pcm 7 2 7 3 7 4 7 5

    p

    ai

    mkp

    rk = rkmk*mk*mk


    7 6 2 dpcm

    7.6.2(DPCM)

    64kb/sAPCM PCM3.1 kHzPCM

    64kb/s


    7 7 1 pcm 7 2 7 3 7 4 7 5

    32kb/s64kb/sPCMADPCM

    ADPCMDPCMDPCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • DPCM

      DPCM1

      p = 1a1 = 1sk = sk-1*

      1TsDPCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    Ts

    Ts

    (b)

    (a)

    DPCM(ADPCM )


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • DPCM

      DPCMqkmkmk*

      ek(+, -)Mv

      M = 4 vM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • fm


    7 7 1 pcm 7 2 7 3 7 4 7 5

    DPCM, DPCMPCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    7.7

    • 7.7.1

    • PCM78/


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • f(t)f(t),f(t)f(t)tf(t)f(t)f(t)f(t)f(t)f(t)f(t)10


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 01f(t)Delta ModulationDMM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • De Loraine1946

    • (1) PCM

    • (2) 102103PCM104106

    • (3)

    • PCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    mk

    rk

    ek

    m(t)

    mk

    mk*

    • (M)DPCMDPCM2DPCM

      • ek = mkmk + rk+ rk1+0-


    7 7 1 pcm 7 2 7 3 7 4 7 5

    rk'

    mk*'

    • mk* = mk*


    7 7 1 pcm 7 2 7 3 7 4 7 5

    T(t)

    (a) (b)

    e(t)

    d(t)

    d'(t)

    m(t)

    m(t)

    • m(t)m (t)e(t)e(t)TsT(t)+1-0


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 9.7.2

    (a) (b)


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • Tsfs = 1 / Tsk

      fsfsfs

      fsPCMDPCM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    fsfk


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • DPCM

      DPCMM = 2, N = 1, DPCM

      M

      DPCMDPCM

    • kb/sPCM(-)


    7 8 7 8 1

    7.8 7.8.1

    • 3.4kHzfH=4kHzPCMfs=8kHzTs=1/fs=125s25s100sPCM0.8s


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 3T125s


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • 802.3125s125s125s3TDM125s


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • TDM125s38


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • ATM538548802.3ATM


    A t m

    ATM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • PCMA/DTDM

    • (STDMStatistical Time Division MultiplexSTDMTDM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    • PCMTDMPCMFDMPCMFDMPCM4kHzPCMA25688125s88000=6400064kb/s64kb/s32kHz1.7PCM8


    7 7 1 pcm 7 2 7 3 7 4 7 5


    7 7 1 pcm 7 2 7 3 7 4 7 5

    m1(t)

    m1(t)

    1

    1

    m2(t)

    m2 (t)

    2

    2

    mN(t)

    mN (t)

    N

    N

    mi(t)

    8 kHz8000TsN Ts/NPAM


    7 7 1 pcm 7 2 7 3 7 4 7 5

    m1(t)

    m2(t)

    m1(t)

    m2(t)

    T+T/N

    2T+T/N

    T/N

    3T+T/N

    1

    1


    7 7 1 pcm 7 2 7 3 7 4 7 5

    PAM


    7 7 1 pcm 7 2 7 3 7 4 7 5

      • TDM

      • ITUTDM(PDH)(SDH)


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