
STA400A
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The main inputs of the STA400A Channel Decoder are the 2nd IF analog signals centered at 6.095 MHz for the
satellite and at 2.99 MHz for the terrestrial branch. The final down-convertion to baseband of the three signals
is digitally performed inside the chip. After the demodulation process, the three TDM data streams are available
and stored into the external memory for further digital processing including TDM decoding and demultiplexing,
time and spatial diversity combining, FEC processing and data stream generation for the external source de-
coding.
The external memory and the PRC-based packed structure of the service layer allow the use of one Viterbi
decoder and RS decoder for the FEC processing of both the combined satellite and terrestrial frames.
The STA400A is designed to work with the STA450A Service/Source Decoder, an external RF Tuner and a
128Mbit Synchronous DRAM. Figure 3 depicts the connection block diagram of the STA400A Channel Decoder
and the external components. The 128Mbit SDRAM may be selected as a single 4Mx8Bitx4Banks or as a dual
2Mx8Bitx4Banks Memory. In the latter case the MCS0 pin must be connected to the chip select input of the
memory and the XMEM_TYPE register (address 0x0630) must be programmed with "0x01" (see section 2.8).
STA400A is fully configurable via the I2C-bus interface.
FUNCTIONAL DESCRIPTION
Figure 3. STA400A Connection Diagram
The 23.92 MHz system clock applied to XTI/MCLK input (pin 33) can be generated by the built-in clock buffer
and an XTAL pi-network as showed in fig.3 or may come from an external source. In both cases the quartz or
the external source must be compliant with the specifications given in the I/O Cell Description (section 3).
In fig.3 the two embedded 10 bits ADCs are used to sample and convert to digital the satellite and terrestrial IF
signals from the tuner. An internal mux, controlled by the ADCSEL input (pin 34), may be used to by-pass the
TUNER
10k
10k
1u
1u
Terr ADC Diff. Input
Sat ADC Diff. Input
AGCs Control
STA400
STA450
IF2TA_N
IF2SA_P
IF2SA_N
TAGC
SAGC
ADCSEL
PCSD1
PCSD
PCDC1
PCDC
MFP_CLK
PLL_SYNC
MCLKO
CLK_IN
DATA LINE
CLK LINE
SDRAM#0
IF2TA_P
M
ADDRESS BUS - 12
DATA BUS - 8
M
BANK ADDRESS - 2
M
I/O MASK - 1
M
M
C
R
COMMAND INPUTS - 3
MCS0
MCS1
CHIP SELECT
C
M
M
C
C
M
M
SDRAM#1
M
S
S
I
TO MICROCONTROLLER
I
I
I
I
I
F
To Functional Test
Interface
XTI/MCLK
XTO
Mobile
Adapter
22pF
22pF
23.92 MHz
From
External
Source
A
PCFS1
PCFS
PCTS_EF1
PCTS_EF