Tuning; Automatic Picture Format Switching; Wss Data - Daewoo DTH-29U3 Service Manual

CP830F Service Manual
5.4.5

TUNING

The AFC information is supplied by the demodulator IC, and becomes available on SDA55xx pin 15 for controlling
software. The controlling software uses this information for tuner frequency tracking ( automatic following ). The AFC
windows is typically between 50 KHz and 100 KHz. The minimum frequency step of the tuner is 50 Khz. This AFC
function is disabled when a program is tuned using the direct frequency entry or after fine tuning adjustment. Therefore
it is recommended to tune channel with the TV search function ( manual or ATSS ) or using the direct channel entry to
enable the Automatic Frequency Control.
5.4.6 AUTOMATIC PICTURE FORMAT SWITCHING When AUTO mode is selected by the user, the television will
automatically select the picture format for the user. If the user does not want to accept this selected format, he can
always override the setting by use of the ZOOM control on the remote control.
The received information used for automatic picture format control (only while AUTO is selected)
is supplied from two sources;
y WSS data (Wide Screen Signalling Information : see the WSS European Telecommunication Standard ETS 300
294).
The voltage level from SCART 1 or SCART 2, pin 8 (slow switching)

5.4.6.1 WSS Data

This digital signal is a received at the beginning of line 23 in each frame. It is not a teletext signal, but the controller
uses the same decoder resources to receive and decode the digital signal.
This is bi-phase encoded using a clock frequency of 5 MHz. In total, 14 data bits are available, in 4 groups.
Group 1 : Aspect Ratio
Group 2 : Enhanced Services
Group 3 : Subtitles
Group 4 : Reserved
The signal contains bits in Data Group 1 which define an Aspect Ratio label, and in Data Group 3
(b10) which defines if subtitles are available in the video. The other data groups have no
application in this TV for picture format selection.
The TV decoder recognises 5 bits of data (where b3 is an odd parity bit for Data Group 1).
Aspect
Position
Ratio label
N/A FORMAT_4_3
CENTRE FORMAT_14_9
TOP FORMAT_14_9
CENTRE FORMAT_16_9
TOP FORMAT_16_9
CENTRE FORMAT_16_9_PLUS
CENTRE FORMAT_14_9_FULL
N/A FORMAT_16_9_ANAM
N/A SUBTITLE_OUT_IMAGE
(b0, b1, b2, b3)
(b4, b5, b6, b7)
(b8, b9, b10)
(b11, b12, b13)
WSS Bits
0 1 2 3
0 0 0 1
1 0 0 0
0 1 0 0
1 1 0 1
0 0 1 0
1 0 1 1
0 1 1 1
1 1 1 0
X X X X
-54-
Format Name
10 Tube 16:9
0 4:3
0 ZOOM 14:9
0 DEFAULT
0 ZOOM 16:9
0 FULL SCREEN FULL SCREEN
0 ZOOM 16:9
0 FULL SCREEN
0 FULL SCREEN
1 FULL SCREEN FULL SCREEN
Tube 4:3
FULL SCREEN
FULL SCREEN
DEFAULT
FULL SCREEN
FULL SCREEN
14:9
16:9