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Automatic Tuning System(ATS)
The Automatic Tuning System initiates a full auto-search of the channel, covering all the bands and
the system available on the TV set. At the end of the search, the microcontroller uses the teletext or
VPS information (when these signals are available ) to find out the TV network name of the channel.
Then the microcontroller sort out the stations.
Each registered TV signal broadcaster is given a Country and Network identification (CNI) code.
These codes are uniquely designated for use by a single broadcast network, by definition. within the
entire world.
In Germany the TV set uses VPS (Video Programming System) signals on video lines 16 and 329 to
pick up the CNI codes of the received signals.
VPS is transmitted in the vertical blanking interval in dedicated TV lines. Transmission is done in
biphase code, and the data contains 15 data words of each 8 bits. The transmission rate is 2.5Mbit/s.
The first 2 of the 15 data words are for synchronization of the receiver and for identification of the data
line. Words 3 and 4 contains a source identification, which is not relevant for VPS.
Word 5 contains a sound identification(mono/dual/stereo sound)
Word 6 displays a program related signal content identification; as is the case for words 7 to 10 it is
not relevant for VPS.
Words 11 to 15 with their 40 bits contain the actual VPS information.
Word number
bit number
In UK and France the TV set uses PDC (Program Delivery Control) information from teletext lines. The
CNI code is transported in a number of possible location (hidden from display in teletext program
guide pages or extension data packet type 26, and in program label of extension data packet type 8/30
format 2).
Sorting
Once the channel search is completed, the programs with PDC signals are given a name.
The TV broadcasting stations with a name (that is with PDC signal ) are sorted according to the list
below. The sorting order depends upon the TV signal. the broadcasting system, and reception
conditions If either BBC1. BBC2 or ITV are not located, then their respective pre-allocated Program
positions (1 to 3) will remain unused.
13
7
8
VPS bit
5
6
number
Code
Country code
Fig 11 : VPS Data format for words 13 and 14
CNI
14
1
2
3
4
7
8
11
12
Network or program provider
19
3DQDVRQLF
5
6
7
8
13
14
15
16
code
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