cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 74

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

1.0 Functional Description
1.3 Device Description
1.3.35 Wide Screen Signaling (WSS)
Figure 1-23. Typical WSS Analog Waveform (NTSC)
1-58
0.5 V
0.0 V
The CX25870/871 supports the WSS methods outlined in the EIAJ CPR-1204
and ITU-R BT.1119 standards. Three serial interface registers control WSS data
insertion. For 525 line NTSC systems, two bits enable the insertion of the WSS
bit data on lines 20 and 283. The EWSSF1 register bit controls line 20 and
EWSSF2 controls line 283. Twenty bits are used to insert the 14 bits of payload,
plus six bits of CRC data. CRC data is not computed and must be inserted by the
user.
for line 23. In this case, the EWSSF1 register enables WSS data insertion on line
23 and EWSSF2 is ignored. Only 14 bits of payload are specified for 625 line
PAL and SECAM systems. No CRC is generated, therefore bits WSSDAT[20:15]
are ignored in these systems.
generate the desired WSS waveform. The increment value is found by:
NOTE:
For 625 line PAL and SECAM systems, WSS data insertion is only specified
WSSINC[19:0] specifies the incremental value of the PQ ratio counter to
525 line:
WSSINC[19:0] = 2
625 line:
WSSINC[19:0] = 2
Figure 1-23
where:F
WSS uses biphase coding of its data bits. The amplitude of the WSS pulses
is 500 mV above black when high and black when low. For further WSS
details, see specification ETS 300294 or ITU-R BT.1119.
5.86 s
(NTSC)
Run-In
clk
= CLKI frequency = CLKO frequency.
illustrates a typical WSS signal, where WSSDAT[14:1] = 0x00.
Conexant
Code
20
20
Start
/ (2.234*10
/ (200*10
Flicker-Free Video Encoder with Ultrascale Technology
Bit 14
-9
*F
-6
*F
clk
clk
)
14 Data Bits
)
NTSC: Field 1, Line 20
PAL:
Field 2, Line 20
Field 1, Line 23
CX25870/871
Bit 1
100381B
100381 040