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System Design Template - Small divisible conference rooms with Beamtracking mics

This system design template shows how the Tesira TCM-1 beamtracking microphone can be used in a typical small 2-way divisible conference room installation. Traditionally, these rooms are designed to allow participants to host local meetings with one another using local presentation capabilities, as well as make conference calls to remote meeting participants over the phone (VoIP or analog POTS) or using a PC-based soft codec.

In this example, the conference room is equipped with two daisy-chained beamtracking microphones that work as one system when the room is combined, and as two separate systems when the room is divided. Meeting attendees will be automatically tracked and picked up by the ceiling microphones, which eliminates any user intervention. Tesira's Acoustic Echo Cancellation (AEC) technology and the TCM-1 beamtracker work together to deliver optimum speech quality to the far end participants. Ceiling speakers are located at suitable positions to evenly cover the room partitions with the far-end voice, USB audio, or auxiliary audio. Amplification for the speakers is provided by the TCM-1A beamtracking microphone, which makes it a genuine one-cable solution and greatly reduces the installation effort. The TesiraFORTÈ AVB VT4 can also interface with analog telephone lines or a VoIP telephony system to allow for a voice-only telephone conference. There is an HD-1 hardware dialer in each of the room partitions as a control point for dialing functions.

Room design

Room Functionality Scope:

  • Two ceiling microphone pendants with beamtracking technology
  • Connection to building phone system (VoIP and/or analog POTS)
  • USB connection to local PC for soft codec (only in Room Partition 1)
  • Stereo user source audio inputs
  • HD-1 dialers
  • Lo-Z ceiling speakers for playback of voice signals (VoIP, soft codec)

Equipment list

Below is the list of Biamp equipment used in this project:

  • 1 - TesiraFORTÉ AVB VT4        4 mic/line level inputs with AEC; 4 mic/line level outputs with integrated VoIP, POTS, and USB audio
  • 1 - Tesira TCM-1A                      AVB beamtracking ceiling microphone with built-in 2-channel amplifier providing 2x40 Watts burst power
  • 1 - Tesira TCM-1EX                    Extension beamtracking ceiling microphone
  • 2 - Tesira HD-1 dialers               Hardware dialers; 12-button dial pad with access to all Tesira telephony functions, PoE-powered

Note that other non-Biamp equipment is required, such as a network switch, PoE and PoE+ injectors, wall plates, and speakers.

System configuration

The example file for this system design template is set up with all the audio I/O, processing, and control points required, and is ready to load to the system and begin setting up the room gain structure.

In the file, the Room Combiner blocks are already in place to support the room design requirements. Two AEC processing channels on the TesiraFORTÉ AVB VT4 will be occupied by the TCM-1A and TCM-1EX microphones. All four analog audio inputs are used for two stereo audio feeds from auxiliary sources. No analog outputs will be required in this setup, as the speakers are connected to the TCM-1A amplifier, represented by a separate two-channel output block.

USB initialization in the file has been set up to support a 1x1 audio configuration with computer AEC disabled for the PC connection. When the room is divided, USB interface can only be used in Room Partition 1. 

To support the conferencing needs of the space, the microphone signals are routed to the VoIP and USB outputs. All AEC references have been made in the file for proper echo cancelation of conferencing sources. The file's Equipment Table is populated with the proper hardware to match the layout, but it will need to have serial numbers and proxy host assignments added before loading the file to the system. Telephone Interface blocks may be added on demand if it is the preferred method of connection to the telephone network.

The system file includes Room Combiner blocks to support the combining functionality of the space. Within the sample file this functionality is controlled via presets, these presets can be recalled by a command from a 3rd party control systems.

The .zip file below contains the example Tesira configuration files for this conference room application.

File Download:  System Design Template – Small 2-way Divisible Conference Room with Beamtracking Mics.zip

Networking details

This conference room application will make use of a single-cable Ethernet AVB connection between the TesiraFORTÉ AVB VT4 and the TCM-1A for audio, control, and power. In regards to cable types and lengths, the common rules to Gigabit Ethernet cabling apply. The extension TCM-1EX microphone is daisy-chained to the TCM-1A host microphone using Cat.5e (or higher category) cable, but the maximum length of the link must not exceed 33ft or 10m.

The control port of TesiraFORTÉ, as well as the HD-1 dialers, must be connected to the same network, typically the control network which might be shared with other AV devices. As per factory default settings, the devices will look for a DHCP server on the network or, in its absence, will self-assign a Zeroconf address. Static IP addresses may be assigned to the HD-1 or TesiraFORTÉ if desired, but make sure to make changes on the remote devices first and on the Proxy device (in this case TesiraFORTÉ) last.

Setup Requirements:

  • Control network switch with sufficient ports
    • Optional: PoE capable switch to provide power for the HD-1 dialers
  • Two 802.3af (Class 1) PoE injectors for powering the HD-1 dialers (unless the Control switch provides PoE).
  • 802.3at (Class 4) PoE+ injector for powering the TCM-1A (unless an AVB switch that provides PoE+ is used).
  • The HD-1 dialers are configured to receive IP-addresses by a DHCP server on the network or via Zeroconf addressing scheme.
  • Note that the TCM-1A uses Layer 2 AVB for audio and control data, IP-address setup is not required.

After these control and AVB network setup steps are complete, you will be ready to send your compiled system configuration to the hardware.

Microphone and speaker placement

The room

Arguably the single most important element in a conference system is the room itself. A noisy and reverberant room will generally result in lower intelligibility and a poorer conferencing experience for both the near and far ends. A properly designed room with controlled reverberation and low noise floor will generally sound good for conferencing.

The importance of creating a controlled acoustic environment cannot be overstated. It is important to make the room as quiet as possible (lower noise floor) and minimize reverberance (shorter RT60) in preparation for installing the conferencing system. When properly applied, soundproofing and acoustic treatments will yield dramatic improvements in performance for most rooms.

Microphone placement 

calc.pngEven though the TCM-1 beamtracking microphone uses state of the art technology to track a person's voice while reducing unwanted background noise, the laws of physics can't be ignored when deciding on the right placement of a microphone. A good signal-to-noise ratio is key in every part of the audio signal chain, and, for a typical microphone pickup scenario, this translates to avoiding large distances between the mic and the talker. The TCM-1 Calculator will help to find the right pendant height for the expected coverage area. Here are a few more tips to an ideal microphone placement:

  • Keep the distance to the talker as short as possible.
  • Keep the distance to the ceiling speakers as long as possible.
  • Stay away from noise sources like projector fans and air vents.

Speaker placement

Placing speakers in a room can be as equally critical as finding the right spot for a microphone. An ideal positioning of multiple ceiling speakers will achieve an even SPL coverage and a good speech intelligibility across the entire room. In order to get a better sense on how much SPL the speaker of choice is able to produce with the given power of our TCM-1A amplifier, the Amplifier Power Calculator will provide some answers. In addition, a speaker simulation software might be able to predict the expected in-room STI values.

In this example, the speakers are not being used for voice-lift or similar live speech reinforcement, hence gain before feedback doesn't have to be considered. Still, avoiding short distances between the speakers (far-end audio) and the microphone will help to improve the AEC performance.

Audio setup

  • Follow Gain Structure best practices to set input and output levels of microphones and sources. Input and output gain levels have been left at default settings for integration flexibility of the file. Input and Output metering has been added to assist with setting gain structure within the file. New meters can be added to the file as required to allow for additional detail at point along the signal path.
  • Connect wall plates to TesiraFORTÉ AVB VT4 inputs 1-4. Users personal devices will most likely have 3.5mm Stereo Mini-Jack connections, so it is recommended that proper Y-cables are provided in the rooms to allow for user devices to be connected to the wall plates. Please refer to the Wiring audio inputs and outputs article ('Stereo Unbalanced Line Input' section) for information on how to prepare such a cable.
  • Ensure that the proper VoIP setup is done and the system is ready to make and receive calls.
  • Connect USB to PC for soft codec integration if required. Reference the USB interface setup document if needed. Remember that when the room is divided, USB interface can only be used in Room Partition 1.
  • Reference AEC setup in Tesira and AEC best practices documentation and begin to do some test calls with the system. ERL values between 0dB and +15dB are optimal.
  • Level and mute controls have been added to the file pre and post the Matrix Mixer block. These are added for flexibility to meet the design criteria and tastes of the client or integrator. These level controls have been left with their default maximum and minimum values in place, but can be adjusted to fit the needs of the space.
  • The HD-1 dialers have tactile controls for level and mute functions. It is important to note that these control level and mute parameters on the VoIP blocks themselves, and they cannot be assigned to the standard level controls.
  • Uber Filters have been added to all signal paths to allow for any additional equalization as needed. It is recommended to use the advanced filters section of the AEC channel processing block for any high pass filtering needed on conference table microphone inputs. Additional filtering or dynamics blocks may be added or changed as needed to achieve the desired results in the file.
  • Parametric EQ blocks can be added to all speaker outputs to allow for tuning and equalization in each zone. For a more detailed guide on sound system optimization, we have provided Equalizing loudspeakers in a sound system article.

VoIP setup 

If a VoIP phone line is to be used, it must be correctly configured to register with the in-house VoIP phone system. Biamp VoIP interfaces have been tested and/or certified to work with the VoIP telephony systems listed here. Biamp VoIP interfaces may also be able to work with other SIP-based VoIP systems, but they haven't been tested or certified with those systems. 

When integrating Tesira with one of the tested/certified VoIP systems, it is best to follow the detailed instructions in the appropriate article to ensure a successful deployment. Detailed instructions can be found in the VoIP section of this site.

The basic steps to configure the VoIP interface start with opening the VoIP Control/Status block configuration dialog to access VoIP settings:

Screen Shot 2017-11-13 at 4.24.15 PM.png
Click to see the configuration dialog 

There are some required fields in the Network and Protocol tabs of the VoIP Control/Status block that must be filled in correctly for successful VoIP endpoint registration:

  • Network Tab:
    • IP Address / Netmask /Gateway - The VoIP card must have an appropriate IP configuration for the network it is connected to
    • VLAN Tagging - If the VoIP card is on a "tagged" VLAN, this must be enabled and the correct VLAN ID must be provided. If the VoIP card is on an "untagged" VLAN (or no VLAN), this should not be enabled.
  • Protocol Tab:
    • SIP User Name - This is usually the extension number that the VoIP interface will use.
    • Authentication User Name / Password - The username and password required to authenticate this extension.
    • Proxy Vendor - Selecting the correct vendor will ensure that the VoIP interface correctly tailors its communications to the VoIP system.
    • Proxy Address - The IP address of the VoIP proxy server (also known as VoIP server, Call Manager server).

Much of the above information must be obtained from the customer's IT or VoIP team. The following document was designed to facilitate the process of obtaining this information. Provide this documentation to the IT/VoIP team and ask them to fill it out:

VoIP Checklist Form

Control integration

HD-1 Setup: The HD-1 dialers in this system are standard Ethernet device and require 802.3af Class 1 PoE. The default network configuration of HD-1 units is DHCP, so if there is no DHCP server on the Tesira network the units will revert to link-local addressing (IP address 169.254.xxx.xxx, Subnet Mask 255.255.0.0) schemes. An HD-1 will display "Waiting for Configuration..." on the screen until a configuration file has been loaded to the TesiraFORTÉ AVB VT4. Device ID of the HD-1 is used to associate the block with the physical HD-1, it needs to be set in 2 places: the HD-1 processing block and in the HD-1 hardware. The HD-1 must be associated with a specific VoIP card in the software. The HD-1 and VoIP card will then share an identification number seen at the bottom right corner of the blocks. It is also important to note that the buttons on the HD-1 have fixed functionality and cannot be programmed in the software to perform specific functions. The complete HD-1 configuration article can be found here.

Control System Integration: The example Tesira configuration file for this application has been set up to allow third-party control systems to easily control the Tesira system. There are control points for Dialing, Level, Mute, and Room Combiners presets already in place to allow for you to use as it as-is or add additional control points to suit the client's needs. Control points within the file have been noted with an additional text box showing their current Instance ID Tag. These tags can be changed to suit the programmer workflow or standardization.