2005
1. -
, . 0< < , > , < < 1 ( ). . 1, - , .
. 1. - . | 2. . |
0 ( =1 . 1), , . 2. 1, 2 ( 1 2 - ). 1 3 , 2 20 2100 ( 0,1 20,00001).
s =0 , , - =0. , - , c. 1, .
, , , 1, 2, , 1, . 1, 1, 2, , 1 . 2. , , . , . 1 . 2. ( , .) ( ) . . 3 . . . 4.
. 3. - . | . 4. - . |
|
|
1.1.
, - , n - :
, (n= 1,2,3). | (1) |
( ) . .
:
(2) |
. , . . =1 /, n =2, 4, 6...
, | (3) |
n =3, 5, 7,...
(4) |
, - . . , .
, , . 2 1 (), 2 (), (/) f () TW,
TW = 1 2. | (5) |
(, 2 1.) n, .
, (1) n.
(6) |
(5)
1/ =(TW / c)+1, | (7) |
(6) n , 1. TW / c . , W c , .
- =0 n - . , . , , , .
( ), , . - , , .
|
|
1.2.
- , :
, (n =1, 2, 3...). | (8) |
, n n :
Cn (x)=cos(n arcos(x)). | (9) |
- , n . , . , n. .
, . =1, .. . 3 A=1, RW = A A 1
. | (10) |
, RW, .
,
, | (11) |
. , 1/2 , =1/2 ( =0,3493). , (11) ,
. | (12) |
3 , (11) =1 ( , =0,99763, 1g10(2) 0,3).
- . 1 =1, . 2, 1. c=1 / . 3,. . , 3 , :
. | (13) |
, c = 3 =1, 3 .
(8) =1 :
. | (14) |
- - , . ( ) . 27- . 5. . 5 . , . , - - .
. 5. .
1.3.
- , , , . - . 6.
|
|
. 6. - n =5.
. , (RW), , . 6 :
PRW =20log10(A 1). | (15) |
( ) SL, , :
MSL =20log10 (A 2). | (16) |
W, , :
TW = 1 c. | (17) |
RW SL TW. , . 6 1, A 2 c , , 1> c.
n :
, | (18) |
n
, | (19) |
0, 0, i, i, bi, ci .
i, bi ci . .
2.
2.1.
, . , , .
. . , .
, , :
1) ;
2) ;
3) ;
4) ;
5) .
, . , .
.
"" . , .
z -. . z - .
|
|
, . : x (t), (. . X (jw) , X (jw)=0 w > wm), , , ,
=2 / s s 2 m. |
, , ws. , . .
2.2.
2.2.1. .
:
, | (20) |
y (n) n N M 1 .
, (20) .
, am =0, m =1, 2,..., (31) :
, | (21) |
. . N 1 . , (21), .
, , .
. 7. .
. 8. .
- , (N - ), .. n =0, 1,..., N 1.
- , n =0, 1,...
, -, -, -. ( ), , , , - -, [12].
2.3. - -
, . . ( jq) q 2 p:
( j)= [ j ( + m2)], | (22) |
m . - p p. , ( jq) q - p p, q. ( jq) ,
( j)= ( j)e j (), | (23) |
ï ( jq)ï - , j (q) () .
- , , ( jq) q 0 p z -.
, - . :
H (e j)2= H (z) H (z 1), z =e j. | (24) |
|
|
t (q) :
()= d ()/ d. | (25) |
.
, . , . , . , . , z 1. ,
(z)= a 0+ a 1 z -1+...+ a M z M, | (26) |
(-). , ,
, | (27) |
(-). - , , - . - , (z), (27), z - , bk , a 0= a 1=...= ak -1=0. , , b 0=1. , - :
. | (28) |
2.3.1 -
- (29).
. | (29) |
, z s (29) . , - . , . , - .
1. H (s), .
2. , H (s) H (z), -, .
, , , , .
1. .
. , h (n) h (t).
1. : .
2. H (s) , .
3. h (t) , 2.
4. h (n) h (n)= h (t) t = nDt.
5. H (z) z - , 4, :
. | (30) |
6. : , 5, 1.
. - , . . .
2. .
, s- z -. . , :
. | (31) |
:
(0; 0) (1; 0), (0; ¥) (0; -¥) (-1; 0).
(31) . , z - s- . , . (s) (31) (z) .
, . , , . , - 0< w <¥, , (31), - 0 p. q w :
. | (32) |
. , . . , . , .
3. .
. , . - . . , -, . , . (- ) , . , , .
- . . , . . - . , , . . .
2.3.2. -.
-
, | (33) |
N. - :
h (n)= h (N l n), | (34) |
n =0, 1,..., (N /2)1, N , n =0, 1,..., (N 1)/2, N , .
-.
1. .
(33) - - :
, | (35) |
N - . h (n) (z) - (35) :
(36) |
. | (37) |
(37) -.
, Hd (e jq) p < q < p. , q. , . . N - :
, q =2 pk / N, | (38) |
k =0, 1, 2, , N 1. (38), - (37). q =2 pk / N k =0, 1, 2,..., N l.
2. .
( jq) q, :
, | (39) |
. | (40) |
, h (n) .
-, ( jq), (39) . , . , . , (39) - .
w (n), , (39) hd (n) , :
hd (n)= h (n) w (n), | (41) |
w (n) , . . w (n)=0 n > N n <0. (41) , hd (n) N .
, , . . . .
:
) :
) :
) :
, - . - . , - . -. , - . - , -, : , .
2.3.3 z- .
z- , :
1. , - .
2. z=0 - -.
3. ( ) , ( ).
4. , , .. , .
- z- 6- , :
, .
, , MATLAB 6.1 Signal Processing Tool (SPTool) , , .
. MATLAB 6.1. - t. Command Window :
>> t=(0:.01:2);
t 0 2 0,01 .
y(t), 1 1 , 0.25 3 :
>> y=sin(2*pi*1*t)+0.25*sin(2*pi*3*t);
, t , y . f =1 ( 1) . , MATLAB , .
y(t):
>> plot(t,y);
Signal Processing Tool (SPTool), :
>> sptool
File Import Source From Workspace. Workspace Contents , ( y), . Sampling Frequency . t, ( t 0,01, , , 100).
(42) |
Name , SPTool. . Ok.
Signals . View Signals, .
. Filters . View Filters, Filter Viever. :
- - ( , ; , );
- - ( , ; , );
- ;
- ;
- .
New, . Edit . Filter Designer , .
Sampling Frequency . Algorithm :
- - ;
- - ;
- - ;
- - ;
- - ;
- - ;
- - .
Pole/Zero Editor Z - .
( Minimum Order), Order ( ). .
Type : , , .
.
, Auto Design.
, Signals, Filters Apply. ( ) . Ok. Signals. .
1. , 1, 3, 5 , 1, 0.5 0.75 . SPTool , :
) ;
) ;
) ;
) ;
, , () .
2. - . , , . .
3. - - . . , .
4. 10 20 , 5 1000 .
- :
- 1000 ;
- 2 ;
- 5 ;
- 495 ;
- 498 ;
- 1;
- 60.
- (Equiripple FIR) .
. - -.
5. Pole/Zero Editor :
) ;
) ;
) ;
) () .
6. Filter Design & Analysis Tool
>>fdatool
- (FIR Window) :
- 50;
- 2000 ;
- 250 ;
- 750 .
200 . , 40 200 ?
1. 4 -.
2. (), ()?
3. ?
4. -.
5. -.
6. - -.
7. .