TPU 3035, TPU 3040
PRELIMINARY DATA SHEET
43
1
22
24
23
TPU 3040
42
MUX
ADC
Slicer
7–18
Clamping
AGC
44
3
4
5
6
19
20
2
I C-Bus
Program
RAM
Program
ROM
DRAM
Interface
65C02
Interface
21
2
Timer
Interrupt
Watchdog
Skew
Delay
DMA
Interface
WST
Layer
29
36
37
38
39
27
28
RGB &
PRIO
Interface
Sync
Interface
Character
ROM
OSD
Layer
Clock
Generator
25
26
30 31
32
33
41
40
34
35
Fig. 2–1: Functional block diagram of TPU 3040
2.2. Teletext Acquisition
tions. The slicer can be programmed to different bit rates
for reception of PAL, NTSC or MAC world system tele-
text as well as VPS,WSS or CAPTION signals.
Theonlytaskoftheslicercircuitistoextractteletextlines
from the incoming composite video signal and to store
them into the acquisition scratch buffer of the external
DRAM. No page selection is done at this hardware level.
2.3. Teletext Page Management
As a state-of-the-art teletext decoder the TPU 3040 is
able to store and manage a sufficient number of teletext
pages to absorb the annoying transmission cycle times.
The number of available pages is only limited by the
memory size. With an intelligent software and a 16 Mbit
DRAM it is possible to store and to control more than
2000 teletext pages.
Two analog sources can be connected, thus it is pos-
sible to receive text from one channel while watching
another on the screen. After clamping and AGC amplifi-
er the analog video signal is converted into binary data.
Syncseparation is done by a sync slicer and a horizontal
PLL, which generate the horizontal and vertical timing.
By these means no external sync signals are needed
and any available signal source can be used for teletext
reception.
The management of such a data base is a typical soft-
ware task and is therefore performed by the 65C02. Us-
ingafixedlengthpagetablewithoneentryforeverypos-
sible page, the software distributes the content of the
acquisition scratch buffer among the page memory. The
page size is fixed to 1 KByte, only ghost rows are
The teletext information itself is acquired using adaptive
slicers on bit and byte level with soft error detection to
decrease the bit error rate under bad reception condi-
MICRONAS INTERMETALL
7
MICRONAS [ MICRONAS ]
