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Biamp Systems

Using the Tesira EX-UBT

The EX-UBT is a compact remote expander that uses the AVB2018-08-22_11h24_13.png networking protocol to extend USB and/or Bluetooth sources back to a rack-mounted Tesira server-class device. A standard USB cable connects the host computer to the EX-UBT. CAT5e cabling or better is required for the network connection, with a maximum distance of up to 100 meters (328 ft) allowed to the equipment rack. The EX-UBT is an IEEE 802.3at Class 2 device requiring 7 watts of power from a PoE-capable switch or mid-span injector. 

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LED Indication

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Features

USB

The EX-UBT USB port acts as a client to the connected host computer. Within Tesira software, the USB can be configured to pass audio in/out according to one of the following options:

  • Mono (1 input x 1 output)
  • Stereo (2 inputs x 2 outputs)
  • Multi-Channel (8 inputs x 8 outputs)

When configured as a speakerphone, the EX-UBT synchronizes privacy mute state and volume control of Microsoft Skype for Business running on the connected host computer. This is achieved through Human Interface Device (HID) communication.

Bluetooth & NFC

Bluetooth capability may be enabled/disabled when the EX-UBT is configured in Tesira software. The Bluetooth module supports the following Bluetooth subset profiles:

  • Hands-Free Profile (HFP)
  • Advanced Audio Distribution Profile (A2DP)
    • A2DP is supported as an audio sink, and allows the following codecs to be received:
      • SBC
      • Qualcomm® aptX™ audio
      • AAC

Bluetooth pairing may also be made via pre-configured Near Field Communication (NFC) tags. NFC tags allow users with NFC capable/enabled devices to quickly pair with the EX-UBT by tapping their device to the tag. Instructions for enabling the NFC function will vary by device. Note that Apple® devices do not support NFC-assisted compatibility at this time. 

Each EX-UBT ships with two NFC tags that have been configured with the default hostname of the associated EX-UBT and are write-protected.

 NFC - front.jpg  NFC - back.jpg

Software & programming

Configurations for the Tesira EX-UBT are available from the Object Toolbar via the Telephony/Communications menu item:

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When the Tesira EX-UBT object type is selected from the Audio Object Toolbar, the EX-UBT Initialization dialog window is displayed:2018-08-21_15h56_37.png

Users may check to use USB, Bluetooth or both.

USB Channel Count - This allows the user to select between three different channel configurations:

  • Mono                     1 input x 1 output channel
  • Stereo                    2 input channels x 2 output channels
  • Multi-channel        8 input channels x 8 output channels

USB Connection Type - The two Speakerphone modes provide single or stereo audio input and output streams for use with a soft codec application on a host computer. The USB Input represents the incoming audio from the soft codec, and the USB Output is used to send audio to the far side.

Speakerphone: Disables Computer AEC – In this mode, the Acoustic Echo Cancellation (AEC) function will be provided by the AEC block in the Tesira DSP. A control message is transmitted to the soft codec via the USB link telling it to disable its internal AEC.

Speakerphone: Enables Computer AEC – This mode is for situations where the soft codec will provide the AEC function.

Line In/Out – This mode provides up to eight channels of audio. Combinations of 2, 4, 6 or 8 total USB channels can operate in fixed 24 Bit, 48 kHz.

Mute USB inputs as a group - Selecting this mutes all USB input channels when the mute state of a single input channel is changed. This selection is checked and cannot be deselected if either of the Speakerphone USB terminal types is selected. It is also checked by default if the Line In/Out USB terminal type is selected.

Mute USB outputs as a group - Selecting this mutes all USB output channels when the mute state of a single output channel is changed. This selection is checked and cannot be deselected if either of the Speakerphone USB terminal types is selected. It is also checked by default if the Line In/Out USB terminal type is selected.

Notes on host operating system controls:

  • "USB host" refers to USB on the computer.
  • In Multi-Channel 8x8 Line In/Out mode, changes to the USB host mute and record level controls will be ignored by the EX-UBT.
  • Balance controls will not be synchronized between the USB input block and the USB host when in speakerphone mode (only playback levels are).

DSP blocks

The following images show the DSP blocks associated with different Initialization options:

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For more details regarding EX-UBT logic, please reference tesira-help.biamp.com.

USB Details

When the EX-UBT is connected to a host computer, it will enumerate as an Echo Cancelling Speakerphone or sound device as defined during block initialization. Notice the sound device name also includes the unique serial number of the EX-UBT device.

USB Enumeration.png     USB Enumeration - Speakers.png

 

When the EX-UBT blocks are initialized as a speakerphone and selected as the Default Audio Device in the Windows 10 host computer, mute and volume synchronization occurs upon USB connection. This means that the host computer volume level will synchronize with the volume level of the EX-UBT USB input block in the Tesira configuration. Volume and mute changes made on the host computer or the EX-UBT USB input block will remain synchronized. This behavior is demonstrated in this short video.

When privacy mute is selected in Skype For Business*, the mute state of the EX-UBT Output block mute will track accordingly. Similarly, if the mute logic input of the EX-UBT USB Output block is triggered high, the privacy mute indication in Skype For Business will follow.

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*The synchronization of level and mute states is possible via USB HID communication. Performance may vary with applications other than Skype For Business.

 

EX-UBT Tip:

  • A logic-driven preset can initialize the USB input block level providing a more consistent user experience. This short video provides an example of this concept.

Bluetooth details

The Bluetooth Control/Status block offers four user-settable parameters:

  • Bluetooth Name - Defaults to Tesira EX-UBTxxxxxxxx (where 'xxxxxxxx' represents the EX-UBT's serial number) and can be customized via the 'Edit' button.
  • Inactivity Timeout - An active Bluetooth connection will be disconnected after the defined time period. When set to 0 seconds, a connection will not timeout.
  • Bluetooth Radio - Enabled/Disabled2018-08-27_15h11_26.png
  • Discoverable - Enables/Disables discoverability of the EX-UBT.

 

The Bluetooth Status sub-section offers additional information regarding the paired/connected Bluetooth device:

  • Connected status & Bluetooth Host device name.
  • Streaming status & active Streaming Profile details.
  • MAC Address of the Bluetooth Host device
  • Optional Disconnect button.

 

*Note, third-party control systems can poll, set, and/or subscribe to these attributes via Tesira Text Protocol (TTP).

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Bluetooth Best Practices:

  • Set the Bluetooth name to the meeting room name so that users can identify and associate it accordingly.
  • Enable Bluetooth and make the EX-UBT Discoverable at appropriate times. If a conference room is powered down, it may make sense to disable the Bluetooth Radio.
  • Setting the Inactivity Timeout to a value other than 0 will automatically disconnect Bluetooth devices if they are not actively streaming. This will free up the connection if users forget to disconnect. Values between 60 and 300 are recommended.
  • Setting the Inactivity Timeout to 0 seconds will allow a connected Bluetooth host to remain connected indefinitely.
  • Bluetooth connections are on a "first come, first served" basis. If a host device is already connected, another Bluetooth device cannot bump them off. The Disconnect button can be utilized to bump active connections and permit a new device to connect.

 

Gain Structure & dBFS

Bluetooth and USB source signals are digital Full-Scale signals commonly referred to as dBFS. The audio meters in Tesira software are dBu meters. The following image provides a visual for correlation:

Meters dBFS vs dBu.png

The USB and Bluetooth sources from the EX-UBT are digital (dBFS) sources. When the host device is set to 100% volume, the signal will likely average -12 dBFS but will appear on Tesira audio meters as +12 dBu. If the host volume is set to 50%, the signal will average approximately -24 dBFS or 0 dBu.

As a point of comparison, most analog microphones have their input gain adjusted so that a good signal will meter between 0 and 6 dBu. When mixing dBFS signals with microphone or line level dBu signals in the Tesira configuration, consider using attenuation or dynamics to level match these different source types.

The EX-UBT Bluetooth input block does include a Peak indication LED. This indicator will illuminate when the signal peak is 3 dB below clip (0 dBFS). A brief flickering of this indicator is acceptable and typically indicates the host Bluetooth device volume is likely at 100%. Turning down the volume on the host Bluetooth device will lower the signal accordingly. Based on the expected system performance, users may consider attenuating the Bluetooth input block as shown in the following image:

Bluetooth Input Clip Indicator.png

Powering the EX-UBT - PoE

The EX-UBT is a Power Over Ethernet device which classifies as 802.3at Class 2 (7W). Please note that there are manufacturing and design differences between mid-span PoE injectors. When directly connecting the EX-UBT (or any Tesira expander) to a TesiraFORTE or Tesira Server-IO AVB port, the mid-span PoE injector must support 1 Gbps data link speed. If the mid-span PoE injector does not support 1 Gbps, the EX-UBT power LED will illuminate steady yellow but the LED on the AVB RJ45 port will remain dark indicating no data activity.

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