Kenwood DP-1100 B, Руководство по обслуживанию

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DP-1100B II
II.
FUNDAMENTALS
2 - 6 C R O S S - I N T E R L E A V E
Fig. 2 . 2 s h o w s a p r i n c i p l e of a c r o s s - i n t e r l e a v e . A n
o r i g i n a l series o f signals is d i v i d e d i n t o a n u m b e r of
w o r d s , a n d parity w o r d s are i n s e r t e d .
P
1
= W
1
+ W
2
+ W
3
+ W
4
P
5
= W
5
+ W
6
+ W
7
+ W
8
P
9
=
W
9
+ W
1 0
+ W
N
+ W
1 2
(5)
d e l i v e r e d d i r e c t l y , b u t w o r d s f e d i n t o N o . 2 t o N o . 4 lines
are s u b j e c t t o d e l a y w i t h d e l a y m e m o r i e s by o n e t o t h r e e
w o r d s so t h a t t h e w o r d o r d e r is c h a n g e d (interleaved) at
their respective t e r m i n a l s .
T h e r e is a n a d d e r f o l l o w i n g t h e d e l a y m e m o r i e s , w h e r e
a n o t h e r parity w o r d Q is c r e a t e d .
Four o r i g i n a l series of signals ( W
1 (
W
5
, W
9
, W
1 3
. . . ) , ( W
2
,
W
6
, W
1 0
, W
u
, . . . ) , ( W
3
, W
7
, W
u
, W
1 5
, . . . ) a n d ( W
4
, W
8
,
W
1 2
, W
1 6
, . . . ) a m o n g m a n y o r i g i n a l series of signals are
a r r a n g e d f o r f o u r lines N o . 1 via N o . 4 in Fig. 2 . 2 of
t h e s e w o r d s , t h e w o r d s p a s s i n g t h r o u g h N o . 1 are
Q
1
= W
1
+ W .
2
+ W .
5
+ W -
8
+ W .
1 5
Q
5
= W
5
+ W
2
+ W .
1
+ W .
4
+ P .
U
(6)
Q
9
= W
9
+ W
6
+ W
3
+ W
0
+ P.?
In o t h e r w o r d s , t w o s y s t e m of c o d e s are used o n b o t h
sides of t h e delay m e m o r i e s .
Original series of signals
,W
8
W
7
W
6
W
5
p
1
= w
1
+ w
2
+ w
3
+ w
4
Q
t
= Wj + W
2
+ W_
5
+ W_„ + W .
1 5
P
S
= W
5
+ W
6
+ W
7
+ W
8
Q
5
= W
5
+ W
2
+ W.n + W_
4
+ P _
n
Recorded series of signals
w
5
Q
t
P .
1 5
W_
8
W .
5
W .
2
W
t
Disc recording sequence
F i g . 2 . 2 Principle of C r o s s - I n t e r l e a v e E n c o d e r
(2) Fig. 2 . 3 i n d i c a t e s relations b e t w e e n t w o parity c o d e s .
T h e solid lines m e a n a P's series, a n d t h e d o t t e d lines
m e a n a Q ' s series. Each of t h e m has t h e c a p a b i l i t y of
single erasure c o r r e c t i o n , so t h a t a n error of a single
w o r d c a n be easily c o r r e c t e d of c o u r s e .
T h e s y n d r o m e of e a c h o t h e r ' s series c a n be used as a
p o i n t e r f o r p o i n t i n g o u t a l o c a t i o n of error.
F i g . 2 . 3 C o d e S e r i e s of C r o s s Interleave
(Black circules indicate errors).
1 Word
2 Words
3
Words
4 Words
Adder
Delay memories
Adder
Data Word
Check Word