HDM8515 Datasheet, PDF (56/75 Pages) Hynix Semiconductor – DVB/DSS Compliant Receiver

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Control Parameters for Viterbi and RS Decoders
Bit 0. Parallel or Serial Output
Controls the transport stream output of the 8515 to serial or parallel
mode.
“0” (default) means the 8515 MPEG output is parallel.
“1” means the 8515 MPEG output is serial. The LSB of the data
bus(data[0] - pin 98) is used as the serial output pin.
Bit 1. MPEG2 Data
“0” (default) means the incoming data is MPEG2 decoded. In this mode
a sync byte is expected every 188 bytes.
“1” means non-MPEG2 data. The Viterbi decoder doesn’t check the
existence of the sync byte.
Bit [4:2]. Depuncturing Rate
It defines the depuncturing rate of the Viterbi decoder. When
vb_autocode is disabled, the depuncturing rate is set to this value.
0 --- 1/2
1 --- 2/3
2 --- 3/4
3 --- 5/6
4 --- 7/8
5 --- 6/7
Bit 5. Viterbi Auto Decoding Mode
When this bit is set to 1, the Viterbi decoder automatically finds the
correct code rate of the incoming signal. When this bit is set to 0, the
code rate is set to the user-defined value at bit[4:2]. The default is 0.
Bit 6. DSS Mode
When this bit is set to 0, this device operates as DVB mode. When
this bit is set to 1, this device operates as DSS mode. In that case, the
roll-off factor of the Nyquist filter is set to 0.2. The default is 0 (DVB).
Bit 7. BPSK Mode
When this bit is set to 0, the demodulator assumes the incoming data
is QPSK-modulated. When this bit is set to 1, the demodulator
assumes the incoming data is BPSK-modulated.
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Rate 1/2 Threshold Select
This seven bit parameter defines the threshold used in the Viterbi
decoder node synchronization process. For rate 1/2, the nominal value
is 30 (1EH).
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