SAA2501 Datasheet, PDF (20/52 Pages) NXP Semiconductors – Digital Audio Broadcast DAB decoder

Philips Semiconductors
Digital Audio Broadcast (DAB) decoder
Preliminary specification
SAA2501
handbook, full pagewidth
FDAO
MSB left sample LSB
1
2
24
25
26
MSB right sample
32
1
2
FDAI
SCK
WS
valid data
undefinied data
sub-band
0
1
2
WS
L RL R
30
31
0
1
FDFSY
MLC400
Fig.12 Filter data serial transfer format.
Table 10 Signals of filter data interface
SIGNAL
FDAO
FDEF
FDAI
SCK
WS
FDFSY
DIRECTION
output
output
input
output
output
output
FUNCTION
filter data output
filter data error flag
filter data input (optionally processed)
filter data (output/input common) bit clock; I²S clock output
filter data (output/input common) word select; I²S
filter data output frame synchronization
Two sub-band samples (one per channel) are transmitted
per sample period with output FDAO. The transmission
pattern of the samples S [sb, ch] (sb: sub-band index; ch:
channel) is: S [0, L], S [0, R], S [1, L], S [1, R],..., S [31, R],
S [0, L], S [0, R], etc. Word select signal WS indicates the
channel of each sample (WS is also used for the baseband
audio output interfacing).
The sub-band sample bit clock SCK has a frequency of 64
times the sample frequency. The sub-band samples are
transmitted in 24 bit two's complement Pulse Code
Modulation (PCM) form, MSB first. Thus, of the available
32 FDAO bits per sample per channel, only 24 are used.
The MSB of a sample follows one SCK period after each
transition in WS. The 8 unused bits between individual
samples in FDAO are zero (SCK is used for the baseband
audio output interface as well). The optionally processed
sub-band data signal is fed back as input FDAI in a similar
format as FDAO, but now the 8 unused bits between
individual samples are undefined; they are neglected by
the SAA2501.
A leading edge in signal FDFSY indicates the start of each
FDAO frame. The length of each FDFSY pulse is one
sample period; FDFSY is HIGH during a S[0,L] and S[0,R]
January 1995
20