SAA2501 Datasheet, PDF (30/52 Pages) NXP Semiconductors – Digital Audio Broadcast DAB decoder

Philips Semiconductors
Digital Audio Broadcast (DAB) decoder
Preliminary specification
SAA2501
7.20.9 ERROR REPORT ITEM
The validity of bit allocation plus scale factor select information and the result of the scale factor CRCs (the latter only
when decoding EU147 input data) may be read from the error report item. The error report item is only valid if status flag
INSYNC is set.
Table 26 Error report item; 1 byte (read-only)
SUBSEQUENT
BYTES
Error report
7
6
5
4
3
2
1
0
BALOK⁽¹⁾ DECFM⁽²⁾ undefined undefined SF3OK⁽³⁾ SF2OK⁽³⁾ SF1OK⁽³⁾ SF0OK⁽³⁾
Notes
1. BALOK; bit allocation and scale factor select information validity indication:
a) BALOK = 0; bit allocation or scale factor select information are incorrect, or the CRC (if active) over header, bit
allocation and scale factor select information fail.
b) BALOK = 1; bit allocation or scale factor select information are correct, and the CRC (if active) over header, bit
allocation and scale factor select information passes.
2. DECFM; frame skipping/decoding indication:
a) DECFM = 0; the current input data frame is skipped, and the corresponding baseband audio output frame is
muted due to input data errors or inconsistencies. However, synchronization to the input data is maintained.
b) DECFM = 1; the current frame is decoded normally.
3. SFnOK is invalid when decoding ISO/MPEG input data. When decoding EU147 input data:
a) SFnOK = 0; then one or more scale factors have been concealed in sub-band block (n).
b) SFnOK = 1; no scale factors in sub-band block (n) are concealed (i.e. the error checking has passed).
Blocks 0 to 3 are explained in Table 27.
Table 27 Content of blocks 0 to 3
BLOCK
0
1
2
3
SUB-BANDS
0 to 3
4 to 7
8 to 15
16 to 31
7.20.10 AUDIO SERVICE SYNCHRONIZED DATA ITEM
When decoding EU147 input data, the Audio Service
Synchronized Data (ASSD), which is contained in each
frame, may be read. The subsequent ASSD bytes are read
in reverse order with respect to the input bitstream; the first
ASSD item byte is the last byte in the input bitstream. The
ASSD item is only valid when the status flag INSYNC is
set.
January 1995
30