Conferencing Features

Overview

The robust suite of Conferencing Features includes:

• Automatic Gain Control

• Output Gain Control

• Noise Gating

• Echo Suppression

• Conference Tracking

• Conference Failure Handling

• Channel Selectable Tone Suppression in a Conference

• Increased Number of Conferences

• Configurable Conference Connection Mode

You can configure these features to handle such things as network and signal problems (background noise, echo, and speakers who are too loud or too quiet), conference failure, and conference tracking.

These parameters are especially important for large conferences because as conferences grow, so does the likelihood of impaired signals and networks, and so does the number of users affected. These settings apply to up to two streams of 128 participants.

There are default settings for these features at the card level, and these should work well in most environments. However, you can change the defaults for an entire card, for an entire conference when the conference is created, and for individual conferees (conference legs).

Automatic Gain Control

Automatic Gain Control (AGC) automatically detects variations in volume input and adjusts the input level to be within a decibel range that you can specify, in 1 dB increments. So if a conferee’s voice input (one conference leg) is either too quiet or too loud, AGC adjusts the input so that it falls within your specified acceptable range. You can specify the duration (time constant) of the sample used to determine the volume of the conferee’s voice, in increments of 5 ms.

Output Gain Control

When output gain (volume) is too low or too high, you can control it using the Output Gain Control feature. You can adjust gain from –40dB to +10dB, in increments of 1dB. The CSP acts upon the most recent command. For example, if a change is made at the conference leg level and then at the conference level, the conference level setting overrides the leg level setting because that was the last change made.

Noise Gating

During natural breaks in conversation (when the speaker on a channel is not speaking) if significant ambient noise is coming into a conference from the speaker’s line, that noise can be gated using the Noise Gating feature. As a conference grows in size, ambient noise is more likely to become a problem.

You can customize the time span (time constant) over which noise is measured, in increments of 5 ms. You can also specify a maximum allowable estimated noise level in 1 dBm increments, from
–54 dBm to –10 dBm.

Echo Suppression

If a conference leg is generating echoed signal, you can mute that echoed signal using the Echo Suppression feature. Note how this differs from echo cancellation. Echo Suppression adoptively measures the reflected signal input, and adapts its echo estimate up to a maximum noise value, which you can select in 1 dBm increments, from
–54 dBm to –10 dBm.

Conference Tracking

You can query the channel IDs of the three active (loudest) parties that are being summed together and the time they have been active. The report is returned in the Generic Report message (0x0046).

Conference Failure Handling

If a DSP card, module, or chip that is hosting a conference fails, all the channels in the failed conferences can now be parked instead of purged, although the default is still to purge. You can override this default for all conferences created, individual conferences, or individual conference legs. The application is responsible for rebuilding the conference on another DSP resource or for releasing the conference legs.

Channel Selectable Tone Suppression in a Conference

This feature provides channel selectable DTMF tone suppression on a per-conferee basis. While connecting a channel to a conference, the host indicates whether it wants DTMF tones coming from the conferenced channel to be suppressed (not heard by other channels) or allowed (heard by other channels). The host is also able to modify the DTMF clamping behavior of a channel that is already connected to a conference. The DTMF Clamping/Filtering Enable TLV (0x0604) supports this feature in the following API messages:

• Resource Modify (0x0125) message

• Resource Connect (0x0127) message

• Resource Disconnect (0x0128) message

Increased Number of Conferences

Currently, the CSP supports 511 non-extended conferences. The 9-bit Conference ID limits the number of conferences per CSP to 511. At this time, only 256 conferences per CSP are allowed to have active broadcasts at any one time. A conference has an active broadcast if it has a one-way (listen only) leg attached to it. This number will be increased to 1023 so that all conferences on a CSP may have active broadcasts at the same time.

This feature allows the application administrator to place all E1 and T1 channels in a two-party conference, the minimum conference size allowed. The Extended Conference IDs are supported on both the DSP-ONE and the DSP Series 2 cards.

The application administrator, such as CSA, is required to configure the CSP to handle 1023 conferences (extended conferencing). The extended conference information is stored with the system information and shared with the standby CSP Matrix Series 3 Card.

This feature is implemented by adding a new configuration type, Extended Conferences Enable (0x017) in the System Configuration (0x00AF) and System Configuration Query (0x00B4) messages.

Configurable Conference Connection Mode

When the Configurable Conference Connection Mode feature is enabled, and a transmit tone request is received from the host for a channel that is connected to a conference, the voice traffic on the channel input bus will be connected to the conference and remain while the tone/file is in progress.

Default Mode Enabled

When a transmit tone request is received from the host for a channel that is connected to a conference, the following occurs:

• The channel input (LSD) and output (SLD) buses connected to the conference are temporarily suspended until the transmit tone/file is complete.

• After the call progress tone/file is complete, addition of the channel input and output buses to the conference is resumed.

• Incoming voice traffic is enabled.

Configurable Conference Connection Mode Enabled

When the Configurable Conference Connection Mode feature is enabled, and a transmit tone request is received from the host for a channel that is connected to a conference, the following occurs:

• The transmitter (host) temporarily suspends the output bus (SLD) while the conference receives any incoming voice traffic on the input bus (LSD) to be recorded.

• After the call progress tone/file is complete, addition of the channel input and output buses to the conference is resumed.

• Incoming voice traffic is enabled.

Configuration

See Configuring Conferencing Features.