TMC2192 datasheet(22/69 Pages) CADEKA

22 / 69 page

TMC2192

PRODUCT SPECIFICATION

REV. 1.0.0 8/13/03

Subcarrier Synchronization

There are 5 modes of subcarrier synchronization in the

TMC2192, freerun, subcarrier reset, Genlock, DRS-lock and

Ancillary Data Control (ANC).

•

Freerun

At the rising edge of RESET the DDS starts to generate the

subcarrier reference and will continue to freerun the subcar-

rier. When setting the control register DDSRST is HIGH, the

TMC2192 will reset the DDS to the SYSPH value on the

next ﬁeld 1, line 1 (line 4 for NTSC), pixel 1 occurrence and

will reset this bit to be LOW. This allows the encoder to start

with the correct SCH relationship. The phase of the subcar-

rier reference will drift over time since a 32 bit accumulator

has a error of

±0.5 Hz when generating the subcarrier refer-

ence for NTSC 13.5 MHz.

•

Subcarrier Reset

At the rising edge of RESET the DDS starts to generate the

subcarrier reference and will reset the DDS to the SYSPH

value every ﬁeld 1, line 1 (line 4 for NTSC), pixel 1 occur-

rence. This enables the encoder to maintain the proper SCH

relationship.

•

Genlock

The Genlock mode allows the TMC2192 to lock to a com-

posite reference when used in conjunction with the

TMC22071A Genlocking Video Digitizer. The TMC22071A

produces a genlock reference signal (GRS) which contains

ﬁeld identiﬁcation, PALODD status, relative phase and rela-

tive frequency of the composite reference. The GRS is sam-

pled on the CVBS bus 60 PXCK’s after the falling edge of

HSIN. The phase and frequency values are used to update

the DDS on a line to line basis, thus synchronizing the sub-

carrier to an external composite reference.

•

DRS-Lock

The DRS-Lock mode allows the TMC2192 to lock its com-

posite output to the decoded composite or S-video input of

the TMC22x5y. The TMC22x5y produces a decoder refer-

ence signal (DRS) which contains ﬁeld identiﬁcation, PAL-

ODD status, relative phase and relative frequency of the

composite or S-video input. The DRS is sampled on either

the CVBS bus or the PD port, depending on DRSSEL, 60

PXCK’s after the falling edge of HSIN. The phase and fre-

quency values are used to update the DDS on a line to line

basis, thus synchronizing the subcarrier to an external com-

posite reference.

•

Ancillary Data Control (ANC)

Subcarrier synchronization in ANC mode is covered in the

Ancillary Data Control section of this data sheet.

SCH Phase Error Correction

SCH refers to the timing relationship between the 50% point

of the leading edge of horizontal sync and the positive or

negative zero-crossing of the color burst subcarrier refer-

ence. SCH error is usually expressed in degrees of subcarrier

phase. In PAL, SCH is deﬁned for line 1 of ﬁeld 1, but since

there is no color burst on line 1, SCH is usually measured at

line 7 of ﬁeld 1. The need to specify SCH relative to a partic-

ular line in PAL is due to the 25 Hz offset of PAL subcarrier

frequency. Since NTSC has no such 25 Hz offset, SCH

applies to all lines.

The SCH relationship is important in the TMC2192 when

two video sources are being combined or if the composite

video output is externally combined with another video

source. In these cases, improper SCH phasing will result in a

noticeable horizontal jump of one image with respect to

another and/or a change in hue proportional to the SCH error

between the two sources.

SCH phasing can be adjusted by modifying BURPH and

SYSPH values by equal amounts. SCH is advanced/delayed

by one degree by increasing/decreasing the value of BURPH

and SYSPH by approximately B6h. An SCH error of 15

o is

corrected with SYSPH and BURPH offsets of AAAh.

Table 11. Standard Subcarrier Parameters

Standard

Field

Rate

(Hz)

Horizontal

Freq.

(kHz)

Pixel

Rate

(Mpps)

PXCK

Freq.

(MHz)

Subcarrier

Freq.

(MHz)

Subcarrier Register (hex)

BURPHM BURPHL

SYSPHM

SYSPHL

FREQM

FREQ2 FREQ3 FREQL

NTSC sqr. pixel

59.94

15.734266

12.27

24.54

3.57954500

NTSC CCIR-601

59.94

15.734266

13.50

27.00

3.57954500

NTSC 4x FSC

59.94

15.734266

14.32

28.64

3.57954500

PAL sqr. pixel

50.00

15.625000

14.75

29.50

4.43361875

PAL CCIR-601

50.00

15.625000

13.50

27.00

4.43361875

PAL 15 Mpps

50.00

15.625000

15.00

30.00

4.43361875

PAL-M sqr.pixel

60.00

15.750000

12.50

25.01

3.57561149

PAL-M CCIR-601

60.00

15,750000

13.50

27.00

3.57561149

PAL-M 4x FSC

60.00

15,750000

14.30

28.60

3.57561149

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