參數(shù)資料
型號: ADV7176A*
廠商: Analog Devices, Inc.
英文描述: High Quality. 10-Bit. Digital CCIR-601 to PAL/NTSC Video Encoder
中文描述: 較高的質(zhì)量。 10位。數(shù)字無線電咨詢委員會- 601的PAL / NTSC制式視頻編碼器
文件頁數(shù): 31/52頁
文件大?。?/td> 629K
ADV7175A/ADV7176A
–31–
REV. B
APPE NDIX 3
T E LE T E X T INSE RT ION
T ime T
PD
time needed by the ADV7175A/ADV7176A to interpolate input data on T T X and insert it onto the CVBS or Y outputs,
such that it appears T
synT xtOut
= 10.2
μ
s after the leading edge of the horizontal signal. T ime T xt
Del
is the pipeline delay time by the
source that is gated by the T T REQ signal in order to deliver T T X data.
With the programmability that is offered with T T X REQ signal on the Rising/Falling edges, the T T X data is always inserted at the
correct position of 10.2
μ
s after the leading edge of Horizontal Sync pulse, which enables a source interface with variable pipeline
delays.
T he width of the T T X REQ signal must always be maintained so it allows the insertion of 360 (to comply with the T eletext Standard
“PAL–WST ”) teletext bits at a text data rate of 6.9375 Mbits/s; this is achieved by setting T C03–T C00 to zero. T he insertion win-
dow is not open if the T eletext Enable bit (MR34) is set to zero.
T eletext Protocol
T he relationship between the T T X bit clock (6.9375 MHz) and the system CLOCK (27 MHz) for 50 Hz is given as follows:
27
MHz
4
=
6.75
MHz
6.9375
×
10
6
6.75
×
10
6
=
1.027777
T hus 37 T T X bits correspond to 144 clocks (27 MHz) and each bit has a width of almost four clock cycles. T he ADV7175A/ADV7176A
uses an internal sequencer and variable phase interpolation filter to minimize the phase jitter and thus generate a bandlimited signal
which can be outputted on the CVBS and Y outputs.
At the T T X input the bit duration scheme repeats after every 37 T T X bits or 144 clock cycles. T he protocol requires that T T X bits
10, 19, 28, 37 are carried by three clock cycles, all other bits by four clock cycles. After 37 T T X bits, the next bits with three clock
cycles are 47, 56, 65 and 74. T his scheme holds for all following cycles of 37 T T X bits, until all 360 T T X bits are completed. All
teletext lines are implemented in the same way. Individual control of teletext lines are controlled by T eletext Setup Registers.
ADDRESS & DATA
RUN-IN CLOCK
TELETEXT VBI LINE
45 BYTES (360 BITS) – PAL
Figure 47. Teletext VBI Line
PROGRAMMABLE PULSE EDGES
t
SYNTXTOUT
t
PD
t
PD
10.2
m
s
TXT
ST
TXT
DEL
CVBS/Y
HSYNC
TXTREQ
TXT
DATA
t
SYNTXTOUT
= 10.2
m
s
t
= PIPELINE DELAY THROUGH ADV7175A/ADV7176A
TXT
DEL
= TTXREQ TO TTX (PROGRAMMABLE RANGE = 4 BITS [0–15 CLOCK CYCLES])
Figure 48. Teletext Functionality Diagram
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADV7176AKS 制造商:Analog Devices 功能描述:Video Encoder 4DAC 10-Bit 44-Pin MQFP 制造商:Rochester Electronics LLC 功能描述:VIDEO ENCODER+TELETEXT(NTSC/PAL)I.C. - Bulk 制造商:Analog Devices 功能描述:IC VIDEO ENCODER
ADV7176AKSZ 制造商:Analog Devices 功能描述:Video Encoder 4DAC 10-Bit 44-Pin MQFP 制造商:Analog Devices 功能描述:IC VIDEO ENCODER
ADV7176KS 制造商:AD 制造商全稱:Analog Devices 功能描述:Integrated Digital CCIR-601 YCrCb to PAL/NTSC Video Encoder
ADV7177 制造商:AD 制造商全稱:Analog Devices 功能描述:Integrated Digital CCIR-601 to PAL/NTSC Video Encoder