參數(shù)資料
型號: SAA5250
廠商: NXP Semiconductors N.V.
英文描述: Interface for data acquisition and control for multi-standard teletext systems
中文描述: 接口數(shù)據(jù)采集和控制的多標(biāo)準(zhǔn)圖文電視系統(tǒng)
文件頁數(shù): 14/35頁
文件大小: 173K
代理商: SAA5250
January 1987
14
Philips Semiconductors
Product specification
Interface for data acquisition and control
(for multi-standard teletext systems)
SAA5250
Table 14
Hamming correction (decoding)
Note
1.
A = B8
B6
B2
B1
B = B8
B4
B3
B2
C = B6
B5
B4
B2
D = B8
B7
B6
B5
B4
B3
B2
B1
= exclusive OR gate function
Format processing
The format processing consist of two parts:
part 1
A format transcoder produces a 6-bit code (up to 63) and uses the following as inputs:
DIDON long and short prefixes;
hamming corrected code (4-bits)
accept/reject code condition
table number (see section ‘R1 register’, bits R15 and R14)
Other prefixes (R16 = 1)
6-bit maximum/default format (see section ‘R3 register’)
part 2
A format counter operating at the character clock frequency which receives the 6-bit code from the format transcoder and
is used to check the data packet length following the prefix.
Serial/parallel converter
The serial/parallel converter consists of three parts:
An 8-bit shift register which receives the SD input and operates at the bit frequency (DCK).
An 8-bit parallel register used for storage.
A framing code detection circuit. This logic circuit compares the 8-bits of the R4 register with that of the serial register.
If seven bits out of eight match (in coincidence with a validation window), it produces a start signal for a new teletext
data line to the sequence controller.
A
B
C
D
INTERPRETATION
INFORMATION
1
0
1
0
1
1
1
0
0
1
0
1
1
1
0
0
0
1
1
1
1
0
0
0
1
0
1
1
0
0
0
0
0
0
0
0
1
no error
error on B8
error on B7
error on B6
error on B5
error on B4
error on B3
error on B2
error on B1
multiple errors
accepted
corrected
accepted
corrected
accepted
corrected
accepted
corrected
accepted
rejected
A.B.C = 0
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SAA5250P 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Interface for data acquisition and control for multi-standard teletext systems
SAA5250T 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Interface for data acquisition and control for multi-standard teletext systems
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SAA5252P 制造商:NXP Semiconductors 功能描述:TELETEXT DECODER, PDIP24
SAA5252T 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Line twenty-one acquisition and display LITOD