Table of Contents
Advertisement
S y s t e m
D e s c r i p t i o n
Ext. Bus
V.11
X21_Clk
RXD_V
Clk_Syn
Ext. Bus
V.11
RXD
Ext. Bus
XD
V.11
XC
Add. Data
TXD
V.24
RXD
PAG E 1 8
4.2
The ISO/MPEG Decoder
The Audio Decoder can decode all ISO/MPEG Layer II and ISO/MPEG Layer
III coded data streams, which comply with the ISO/IEC 11172-3 standard. The
following modes are possible
– STEREO
– JOINT STEREO
– DUAL CHANNEL
– MONO
Sampling frequencies of 32-kHz, 44.1-kHz and 48-kHz are supported. If pre-
emphasis signals (J.17, 50/15 µs) are detected in the coded audio data sig-
nals, de-emphasis filters are automatically used in the decoder.
The audio output is realised electronic balanced.
The decoder circuit consists of a DSP and a micro controller. The software for
both can be loaded into a Flash Eprom.
Attention
The MAGIC Encoding Systems support seamless switching of audio modes
and audio data rates. However, the switching of half-sampling frequencies
!
(24-kHz in DAB) by the encoder can only be realised with disturbances. The
Decoder can also process these types of re-configurations without distur-
bances. However, switching from Mono to Stereo (Stereo, Dual Channel,
Joint Stereo) and vice versa will have short breaks.
Presently, half-sampling frequencies cannot be decoded by the Audio De-
coder.
FIG. 5
TTL
Encoded Audio Data
TTL
Hostbus
PCB-Address
UART
TTL
TTL
BLOCK DIAGRAM OF THE AUDIO DECODER
Check Level
D/A-Converter
D
Dig. Aud. Data
Decoder
Layer II
Transmit Clk
VCO
Sampl. Clk (asyn.)
Clock Mux
Sampl. Clk (syn.)
Host
Hostbus
Control
Level
Control
Deemphase
Level
Audio Out
Deem.
Level
A
Audio Out
AES/
SRC
EBU
Clock In/Out
Select Sampl. Clk
Deemph.
Level
Optional
Advertisement
Table of Contents
