8.11 -
8.12 : , (, FSK- Frequency Shift Keying) , , - , .
T. .
.
.
2T,
8.13.
.
, , .
, .
8.12
8.13
8.3.2.
9.4, 8.14.
8.14
, : , .
. .
8.15
8.3.3. ()
8.16.
8.16
, . 8.17.
8.17
|
|
, D-. . ,
.
,
.
, 8.18
8.18
, :
,
k = 1, 2,..
,
.
. (8.1)
,
.
(8.1)
.
m D-, , TT
.
.
, , , , .
23.
8.
8.4.
8.4.1.
, F FM
.
(, MSK Minimum Shift Keying) , .
, .. ,
,
f 3.
, GMSK (Gaussian Minimum Shift Keying). GMSK GSM DECT.
3 , f, B (Band ) BT, T. GMSK.
8.19 8.21 GMSK BT=3, BT=0,5 BT=0,3 .
8.19 - GMSK BT = 3
8.20 - GMSK BT =0,5
8.21 - GMSK BT = 0,3
|
|
BT=0.3 GSM, BT=0.5 DECT.
, FM,
,
v , T .
8.4.2. MSK GMSK
,
,
- , ,
- , - .
, .
, ,
, :
, MSK , , , - , , . 8.22, , 8.23.
8.22 MSK GMSK
MSK, 8.23. , t0.
GMSK MSK , .
8.23
MSK
8.24
8.4.3. MSK
-
8.25 MSK - , 8.26 .
8.25 MSK GMS
-
XN(t) ,
.
sign(x) :
, . 8.26 1,3,5 .
- Xp(t) X1(t) X2(t). X1(t) , X2(t) . . T. X2(t) T.
- 1, C1(t) S1(t) c , ( 4T). .
|
|
MSK :
8.26 MSK
-
, 8.23 .
, .
GMSK .
8.4.4. MSK GMSK
8.27 MSK GMSK.
8.27 MSK GMSK
, , .
8.28.
8.28
. 90- (), , T, .
, , ..
2π f0 T = π L, L .
8.29 xN(t), φ0(t), , φ0(t-T), φ0(t) - φ0(t-T) , .
8.29
.
. , . .
. , , . , , .
8.29 , , .
8.4.5.
8.30 MSK GMSK. , X0c(t) X0s(t).
|
|
- (1), . 1 .
, - FM /2 (2).
2.
.
, , .
. .
, , , .
. , - .
8.31 . 1 φ(t), .
2
, 2π 4 . 2 π , 8.31 , - .
8.30 - MSK GMSK
8.31-
MSK
wc(t), .
, .. .
24.
8.
8.4.
8.32 () (BPSK Binary Phase Shift Keying), 8.33 .
8.32
8.33
, , , .
8.33 , : , , - , 180 .
. , .
, . . 180 . . , .
.
|
|
. , .. , 8.34.
8.34
, . . , . , , 2 1. 2 , 180 360 , .. . , 2.
, .
8.33 , , , , . .
, . .
, .
. .
8.5.
( ) , , .
(, DBPSK Differential Binary Phase Shift Keying):
180 , ( 9.18);
180 ,
.
8.35
.
1.
8.36 , 8.37 .
8.36
, , . .
. , .. , .
8.37
2.
8.38, 8.39 .
8.38
, .
, , .
. , , .
, .
8.39
, , 8.39, .
. , , , . .
8.6.
(DQPSK) . (00 1800) : 00, 900, 1800, 2700. , X1 X2. 8.1 .
8.1
X1X2 | y |
0 0 | |
90 0 | |
180 0 | |
270 0 |
( ) , , . , , .
8.40.
. : . , : , .
8.41
, , . , 90 .
8.40 . , . , , , 180 , 90 270 .
,
,
.
8.40 -
()
u1 u2 - . I1 I2. . I1 . c I2 I1.
8.41 -
I1 u1 u2 , u1, u2. I2. I2 , u2. .
25.
8.
8.7.
8.7.1.
OFDM (Orthogonal frequency-division multiplexing) , . , , BPSK , QPSK , QAM .
K K - . K .
, (), .
OFDM , .
:
,
- k , ,
- - .
, k
i , 0
OFDM - .
, 8.43.
8.44 , 1 2.
8.43 1 2
8.44 1
2
8.7.2. BPSK OFDM
8.45 .
K T K .
I0 , , .
I1, I0 .
(1) - , (2, 3 4).
8.45 -
BPSK-OFDM
- : τ1 τ0. (2, 3 4) .
5, 6 7 , 2, 3 4.
8
, (8.2)
- k - .
OFDM.
9 , , .
OFDM OFDM , 8.46.
8.46 OFDM
8.46 K , .
OFDM.
8.2. (8.2) t .
, Xk,I .
, OFDM Xk,I .
.
OFDM ( 8.47).
.
8.47 - BPSK-OFDM
8.7.3. BPSK OFDM
8.48 BPSK-OFDM.
. 90 , , . .
, - . 8.48 :
- , (1),
- , OFDM (2),
- (3..5),
- - (6).
. I1 , I0 . I0.
- .
8.48 - OFDM
8.49 - BPSK- OFDM
26. ()
8.
8.8. ()
8.8.1.
- , , , .
(, ) , . .
:
- (Direct Sequence Spread Spectrum - DSSS),
- (Frequency Hopping Spread Spectrum - FHSS).
IEEE 802.11 (Radio-Ethernet).
:
- ,
- ,
- ,
- - ,
- ,
- .
, , - , .
8.8.2.
8.50 (DSSS Direct Sequence Spread Spectrum). . u1 u0. u2 u3, .
8.50
8.51. , .
8.51
8.52 .
8.52
u1. . u3 u1. ( , .)
u2, , . , .
8.53 . , . , , , .
8.53
, , . , .
8.54 . D- .
8.54 -
8.2 8 .
1. .
:U1=U4, U4=U3, U3=U2. .
8.2.
U1 | U2 | U3 | U4 | |
, . , 7. , m .
, , , , .
() m=23 8.388, m=43 101.7 , m=61 .
CDMA (code-division multiple access).
8.8..3.
8.55 . ( 8.56). .
8.55
8.56
:
1. ,
2. ,
3. .
, .. .
. .
.
.
, , 0.5.
,
J , , M .
-.
8.57.. , , , , . .
8.57
, IEEE 802.11 (Radio-Ethernet) 79 . (dwell time) 20 .
8
,
( 1) ( 0).
1 T, 0- - .
: . .
.
, , .
1 - , 0 - . . , , . , .
.
, , , , , , .
8
1. ,
2. ,
3. ,
4.
5. ,
6.
7.
8. ,
9. , ?
10. 16,
11. ?
12. ?
13. ?
14. 3 , BT=0.3 4 ?
15. ,
16. ,
17.