PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 147

• Manufacturer Part Number: PSB7238
• Description: Joint Audio Decoder-Encoder - Multimode
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

16-kHz pass-through
A header bit can indicate that the current compressed data is invalid. This means that it
is not decoded and instead the sound from a previous packet is repeated. By that a
simple interpolation of the speech signal is achieved to avoid an audible click.
The size of the command and data packets is the following (header excluded):
Mode
Neutral
G.723
G.728
G.711
G.722
8-kHz pass-through
1)
The communication between user and JADE starts in the neutral mode. To initiate
transfer of speech data, the user sends a command data structure set to the desired
compression mode(s) in a neutral size packet. The mode change affects the JADE’s
input pipeline stage in the next 10 ms period. This means that if the decode mode
changes, the next packet from the user will change in size (corresponding to the new
decode mode), while if the encode mode changes, the third packet from the JADE will
be affected (packets from the JADE represent the output stage of the pipeline). As a
general rule, any changes to the current operating mode or opetions (volume, mute, etc.)
transferred to the JADE from the user take effect on the input captured on the next 10 ms
boundary.
To change compression modes, the user must first send two neutral mode command
packets. The first neutral mode command will be in a full-size packet per the current
operating mode, while the following neutral mode command packet does only contain
the 8 words header. Two neutral packets are required to clear the JADE’s pipeline.
During that time the JADE will reorganize its memory (if required) and re-initialize internal
variables.
Note: When a mode change is requested by the user without sending two neutral
Semiconductor Group
The 8 kHz pass through mode is not available when Host/Host is selected as interface combination for
compressed/uncompressed data.
packets before, the JADE may not work stable.
1)
147
Compressed Words
0
4
40
40
40
80
160
Data Sheet 1998-07-01
Firmware Features
PSB 7238