8.2.7. Tuning the voice quality 
Depending on the available infrastructure, AMO CGWB (DSP branch)offers
different configuration parameters:
- Noise suppression by Voice Activity Detection
- Problem fixing with packet delay and packet sequencing
- Echo suppression
- Sample length
This feature is controlled using the AMO CGWB. When used during operation,
the board data does not need to be explicitly reloaded in this case.
The data immediately comes into effect on the board.
HG 35XX supports various jitter buffer modes. For HG 3500, two different
settings are available:
- Static jitter buffer with drift correction. The length of the jitter buffer always remains constant (it is set to a fixed value in the same way as with "legacy mode," however, the runtime of the incoming signal is not modified).
CHA-CGWB:MTYPE=CGW,LTU=<ltuno>,SLOT=<slotno>,TYPE=JB,JBMODE=1;
-
WBM > Configuration > Voice Gateway > Payload > HW Modules > Display DSP Jitter Settings > Jitter Buffer Type: Static
- The adaptive jitter buffer (default settings). This mode can both correct the drift as well as adapt its depth dynamically. The value set in the JITBUFD parameter is not evaluated in this method. The adaptive jitter buffer is activated via
CHA-CGWB:MTYPE=CGW,LTU=<ltuno>,SLOT=<slotno>,TYPE=JB,JBMODE=2;
-
WBM > Configuration > Payload > HW Modules > Display DSP Jitter Buffer Settings > Jitter Buffer Type: AdaptiveThe jitter buffer can still be optimized with the values for
- Average delay for voice (ms) - AVGDLYV
This defines the standard value (initial value) for the jitter buffer.- Maximum delay for voice (ms) - MAXDLYV
This defines the maximum length of the jitter buffer.- Minimum delay for voice (ms) - MINDLYV
This defines the minimum length of the jitter buffer.- Packet loss/delay preference - PACKLOSS
The jitter buffer can be optimized by the PACKLOSS parameter. The default value 4 should always be preset initially. If the value is set to 0, 1, 2 or 3, the algorithm attempts to prevent packet loss and increases the jitter buffer if problems occur. Conversely, if PACKLOSS= 5, 6, 7 or 8, the algorithm increasingly attempts to always work with a jitter buffer that is as small as possible and accepts a certain degree of packet loss.- Average delay for data (ms) - AVGDLYD
This defines the standard value (initial value) for the jitter buffer for the data service.- Minimum delay for data (ms) - MINDLYD
This defines the maximum length of the jitter buffer for the data service.In HG 3500, it is recommended to use the adaptive jitter buffer. But, if there are older analog fax machines a static jitter buffer could be the better choice.Other important parameters:- Voice Activity Detection: WBM > Configuration > Voice Gateway > Codec-Parameters
- Echo Canceller: WBM > Configuration > Payload > HW Modules > DSP Settings
Additional parameters in AMO CGWB, TYPE=ASC:ParameterDescriptionVADRecognition of silence using Voice Activity Detection (AMO CGWB:TYPE=ASC, VAD=<yes,no>)RTPSample length of the RTP packet depending on the codecs.