STV0118 datasheet(18/42 Pages) STMICROELECTRONICS

18 / 42 page

-5

-10

-15

-20

-25

-30

-35

-40

Frequency (x106) (Hz)

Figure 21 : 1.6MHz Chroma Filter (flt = 10)

101214

-5

-10

-15

-20

-25

-30

-35

-40

Frequency (x106) (Hz)

Figure 22 : 1.9MHz Chroma Filter (flt = 11)

101214

-5

-10

-15

-20

-25

-30

-35

-40

Frequency (x106) (Hz)

Figure 23 : RGB Chroma Filtering

IV - FUNCTIONAL DESCRIPTION (continued)

IV.12 - RGB Encoding

After demultiplexing, the Cr and Cb samples feed

a 4 times interpolation filter. The resulting base-

band chroma signal has a 2.45MHz bandwidth

(Figure 23) and is combined with the filtered luma

component to generate R, G, B samples at 27MHz.

IV.13 - Closed Captioning

Closed-captions (or data from an Extended Data

Service as defined by the Closed-Captions speci-

fication) can be encoded by the circuit. The closed

caption data is delivered to the circuit through the

2C interface. Two dedicated pairs of bytes (two

bytes per field), each pair preceded by a clock

run-in and a start bit can be encoded and inserted

on the luminance path on a selected TV line. The

Clock Run-In and Start code are generated by the

STV0118.

Closed-caption data registers are double-buffered

so that loading can be performed anytime, even

during line 21/284 or any other selected line.

User register 39 (resp. 41) contains the first byte to

send (LSB first) after the start bit on the appropriate

TV line in field 1 (resp. field 2), and user register 40

(resp. 42) contains the second byte to send. The

TV line number where data is to be encoded is

programmble (Reg. 37, 38). Lines that may be

selected include those used by the StarSight data

broadcastsystem. Closed-captions data has prior-

ity over CGMS programmed for the same line.

The internal Clock Run-In generator is based on a

Direct Digital Frequency Synthesizer. The nominal

instantaneousdata rate is 503.5kbit/s(i.e. 32 times

the NTSC line rate). Data LOW corresponds nomi-

nally to 0 IRE, data HIGH corresponds to 50 IRE at

the DAC outputs. Refer to Figure 24.

When closed-captioning is on (bits cc1/cc2 in

Reg.1), the CPU should load the relevant registers

(reg. 39 and 40, or 41 and 42) once every frame at

most (although there is in fact some margin due to

the double-buffering).Two bits are set in the status

tion data registers too frequently, these can be

used to regulate loading rate.

100

150

200

250

300

µs

27.35

µs

13.9

µs

Transition

Time : 220ns

7 cycles

of 504kHz

Figure 24 : Example Closed-caption Waveform

STV0118

18/42

STV0118 数据表(PDF) 18 Page - STMicroelectronics

STV0118 数据表(HTML) 18 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

数据表下载

链接网址

STV0118 数据表(PDF) 18 Page - STMicroelectronics

STV0118 数据表(HTML) 18 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

数据表 下载

链接网址

数据表下载