Download - 张燕 zy29209@163
-
FM(PM)
-
FM
-
4.1 4.2 4.3 4.5 4.8 FDM4.9
-
4.1
-
1(PM)f(t) (KPM)()
-
2(FM)f(t) (KFM)()()
-
()(), , , , , , f(t) f(t) f(t) f(t) 1)2)()()
-
f(t)=Amcosmt
-
PMFM12
-
4-1 AMFMPM
-
4 2
(a)
(b)
PM
d()
dt
f(t)
g(t)
FM
sPM(t)
(b)
sPM(t)
f(t)
(a)
-
4 -3
(a)
(b)
FM
sFM(t)
f(t)
(a)
()dt
f(t)
g(t)
PM
sFM(t)
(b)
-
(-,) FM
-
4-2 KFM =2
(1)fc (2) (3) (4)f(t)
-
(4) f(t)(3)
-
30(NBFM)(NBPM)(WBFM)(WBPM)4.2
-
4.2.1 (NBFM, Narrow Band FM)
-
(NBFM)(AM): 1,c 2BFMfmBFM=2fm 3cc+mc-m
-
(NBFM)(AM) 1NBFM1/(-c)1/(+c) , 2NBFM180 3NBFMAM
-
(NBFM)NBFMAM (AM)
-
4 4 AMNBFM
-
() 4- 6
+
-
-90
f(t)
Acosct
sNBFM(t)
-
4-5 AMNBFM
m
m
m
m
-
*4.2.2 NBPM
-
4- 7
+
-
-90
f(t)
Acosct
sNBPM(t)
-
4.3 WBFMwide band FM FM
-
4.3.1 1
-
, Jn(FM)FMnnn(1)(2)(3)n>1
-
4-8 Jn(FM)- FM(1)(2)(3)(n>1)
1.0
0.8
0.6
0.4
0.2
0
-0.2
-0.4
Jn(FM )
FM
1
2
3
4
5
6
7
8
9
10
11
J0
J1
J2
J3
J4
J5
-
n(012 nnsFM(t),
-
1 2n0AJ0(FM) 3n0cncnmmAJn(FM)
- 4n n 5FM
-
4 9 FM=5
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
J-2
J-1
J-3
J0
J1
J3
J2
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
J-2
J-1
J-3
J0
J1
J3
J2
c+nm
-c-nm
J6
J6
J-6
J-6
J4
J4
J-4
J-4
J-5
J-5
J5
J5
BFM
c
-c
...
...
...
...
-
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
J-2
J-1
J-3
J0
J1
J3
J2
c+nm
J6
J-6
J4
J-4
J-5
J5
BFM
c
...
...
-
2 nJn(FM)n
nmax
-
()1+FM
-
4-10 (a) fmfmaxFM
-
4-10 (b) fmaxfmFM
-
3n=0n0
-
?1FM0J0(0)1A2/22FM0J0(FM)1A2/2
-
3FMFMPC, Pf PFM
-
4-3 2MHz10kHz10kHz(1) (2) (3) (4) fm=10kHzfmax=10kHz(1) BFM=2(fmax+fm)=2(10+10)=40kHz
-
(2) FMFM=2 BFM=2(FM+1)fm=2(2+1)10=60kHz(3) fm=20kHz BFM=2(fmax+fm)=2(10+20)=60kHz(4) FMfm=20kHz BFM=2(FM+1)fm=2(1+1)20=80kHz
-
44 (1)FM=3A(2)FM=0.5: (1)4 J0(3)-0.260 J1(3)0.339 J2(3)0.486 J3(3)0.309 J4(3)0.132 J5(3)0.043(< 0.1)4-11
-
4-11 4-4
-
4
99.60.4
-
(2)FM=0.5J0(0.5)=0.9385, J1(0.5)=0.242, J2(0.5)=0.0306 1
99.9
-
FM AM FMAM AMAMAMAMAM1 FM FMFMFMAM
-
4.3.2
4.3.4
-
*4.3.4 DFMDFMFMfmaxfm
-
4.5 4.5.1 1 4-12
-
(VCO, Voltage Controlled Oscillator)
-
12
1 2
-
4-13
-
1L1C4C3LC1C2Cj2
-
PLL(PLL ------ Phase locked loop)LC 4 14 PLL
PD
LF
VCO
F(t)
FMPM
-
2(NBFM) (4-15) NBFM(WBFM) 4 15
N
f(t)
sNBFM(t)
sWBFM(t)
Acosct
f1, f1, 1
nf1, nf1, n1
n
1
f
1
-
4- 16
+
-
-90
f(t)
Acosct
sNBFM(t)
-
(n2)- si(t)
-
2
2,2
-
nnn
-
fcfrfc+frfc+frfc-fr4-17
-
2
-
f0
02(t)FM
-
4-5 15kHzf1=200kHzf125Hzf275kHzfo90MHznfr
-
f1=25Hzf2=75kHz
90MHz
-
418Armstrong f1f11fcfFM, FM
-
4 - 18Armstrong
FM
NBFM
n1
cos 2f1t
BPF
n2
f(t)
f1
f1
1
n1 f1
n1f1
n11
cos 2frt
n1 f1-fr
n1f1
fFM
fc
sWBFM(t)
n11
-
4-6 4-18 fm=15kHzf1=200kHzf125Hzfr=10.9MHzn1=64n2=48 1 2
-
1f1fm
2f1, f2, n1, n2
-
4.5.2 ----- -----1.
-
-Kd 4 19
(a)
(b)
fc
Kd
(a)
sFM(t)
sd(t)
so(t)
(b)
- KFMf(t)
-
1 ,LCfc4-20
-
4-21
-
LCf0f0fc A(U2m(U2m f(t)(U2m
-
LCu2 4-214-20
-
24-22
-
If01f02 f01 fc= fc-f02uav1uav2
-
f(t)=fcD1D2U1m=U2m, f(t)
-
u0=uav1-uav24-22U2m~f 4-23f01 f02 4-23
-
3PLL 4 24 PLL
PD
VCO
si(t)
sv(t)
uc(t)
-
2 4- 25
sNBFM(t)
si(t)
c(t)
sp(t)
sd(t)
fo(t)
-
4.8 FDM Frequency Division Multiplex (FDM)(TDM)
-
,
-
4.8.1
-
4-27
-
f1(t)
f2(t)
f3(t)
cos1t
cos2t
cos3t
Y()
0
1
2
3
y(t)
0
-m
m
0
-m
m
0
-m
m
F3()
F2()
F1()
-
2
1
3
P1()
0
1
2
3
p1(t)
p2(t)
p3(t)
cos1t
cos2t
cos3t
0
1
2
3
0
1
2
3
P2()
P3()
y(t)
f1(t)
f2(t)
f3(t)
0
-m
m
0
-m
m
0
-m
m
F3()
F2()
F1()
-
BsBg Bs3400HzBg600HzB=4kHz
-
: :
-
4.8.2 4-32
-
nnn2n1
-
12 121212 n1=3, n2=4 n1+n2=7n1+n2=7n1n2+n2=16 16
-
4.8.3
SSB/FM
-
4.9 4.9.1 4-1
-
4.9.2 535kHz1605KHz3.9MHz18MHz4.5kHZB9kHz
-
4.9.3 .,15 KHz,200KHz87MHz108MHz
4.9.4
-
4.9.4 4-44
-
4.9.7 900 MHZ 900MHZ
-
fH3 kHzfmax5kHz B253Bg20kHzBg25 kHz
-
1 2V5kHz,PM5 (1)500HZ1kHZ (2)2kHZ6V4.1 (1) , KPM2, f(t) (2) , KFM2, f(t) (3)
-
4.4 1GHz10kHz10kHz (1) FM (2) (3) (4) 4.8 1kHz s(t)=100cos(ct+25cosmt)(1) m5(2) m1/5
-
4.11 4.112MHz10kHz300kHz
-
2
: (1) (2) FM3 10V
: (1)(2)(3)2103Hz
-
4 600~4kHzSSBFM2(1)(2)
-
4.5 4-1So/NoSin0fm(4.2-18)(4.2-26)(4.2-39)(4.4-8)AM100%1. WBFMDSBSSBVSBAMNBFMAM
-
4-1
-
4-31 DSBSSBAM4.7dBFMmf=6AM22 dBFMmfSSB
-
WBFMDSBSSBVSBAMNBFMAM FMFM,SSB,
-
2. AM AM DSBAM
-
SSBAM, AMSSB
-
VSB VSBSSBVSB VSBVSB+C(VSB+C)AM SSBDSBVSB
-
FM FMFMFMFMFMFMFM