On multiscreen systems such as the CTS-3000 and CTS-3200, the Cisco TelePresence codec uses a distributed architecture with multiple physical codecs participating together as a single, logical unit.
The codecs are rack-mounted to the assembly frame underneath each of the three displays:
- One under the center display (referred to as the primary codec)
- One under the left display (referred to as the secondary codec)
- One under the right display (referred to as the secondary codec)
The primary codec controls the entire system and is the sole interface to the network. The left and right secondary codecs are controlled by the primary codec.
Codec and Component Connectivity
The left and right (secondary) codecs attach to the center (primary) codec through 1000Base-T Gigabit Ethernet jumper cables, and the center (primary) codec attaches to the network through a 1000Base-T Gigabit Ethernet jumper cable.
Displays
The displays connect to their respective codecs through High Density Multimedia Interface (HDMI) cables. As mentioned previously, these are not off-the-shelf displays. They are custom designed by Cisco and engineered specifically for use in Cisco TelePresence systems. Features that are commonly found on off-the-shelf displays, such as multiple user-selectable video input ports, an infrared receiver port and associated remote control, and speakers are not present on these displays. They simply have a power receptacle jack, an on/off switch, and an HDMI port. The codec uses certain pins within the HDMI cable for control signaling messages that control the power state (on, standby, off) of the display, its color temperature (3500 k, 4100 k, 5000 k), and to upload new display firmware code.
Cameras
The cameras connect to their respective codecs through two different cables:
- A 1000Base-T Gigabit Ethernet jumper cable: Provides IEEE 802.af Power over Ethernet to the camera and is also used for control signaling messages, such as setting the gain and color settings, and to upload new camera firmware code.
- A Digital Video Interface to High Density Multimedia Interface (DVI-HDMI) cable: The DVI-HDMI cable is used for the video connection between the camera and the codec.
These cameras are custom designed by Cisco and engineered specifically for use in its TelePresence systems.
Microphones and Speakers
The microphones and speakers attach to the center (primary) codec only. The primary codec contains an audio processing board with DSP resources on it. The secondary codecs do not process any audio. The microphones are custom-designed boundary microphones with an excellent acoustic frequency range and are electronically shielded against cellular interface. They connect to the codec using 6-pin mini-XLR cables. The speakers are off-the-shelf speakers chosen for their excellent sound reproduction qualities and durability and connect to the codec using TRS cables. The speakers are nonamplified. (They do not require a power connection.) The codec contains an amplifier and outputs amplified, speaker-level audio signals to the speakers.
IP Phone
The Cisco Unified IP Phone 7975 Series provides the user interface to the system, allowing the user to make and receive TelePresence calls using a familiar telephony paradigm. The IP Phone attaches to the center (primary) codec using a 1000Base-T Gigabit Ethernet jumper cable. The primary codec provides IEEE 802.3af Power over Ethernet to the IP Phone and communicates using eXtensible Markup Language (XML) over Hypertext Transfer Protocol (HTTP) or Java over Transport Control Protocol (TCP) to create the user interface that displays on the IP Phone’s touch-sensitive screen.
Auxiliary Components
Auxiliary components include PCs, document cameras, and auxiliary displays for viewing the associated video from these devices. The PC is provided by the user and is attached to the center (primary) codec through a Video Graphics Adapter to Digital Video Interface (VGA-DVI) cable and a 3.5mm mini-stereo audio cable. The document camera is an optional third-party component that can be purchased and installed by the customer and is attached to the center (primary) codec through a DVI-HDMI cable and through a 1000Base-T Gigabit Ethernet cable. The Gigabit Ethernet cable controls the document camera, such as power on/off, zoom in/out, and so on.
The video from the PC and the document camera can be displayed on the TelePresence system in one of three ways:
- Multiscreen systems such as the CTS-3000 and CTS-3200 come bundled with an off-the-shelf third-party projector, which is mounted underneath the center of the table and projects onto a white surface below the center display. This projector connects to the center (primary) codec through an HDMI cable.
- Single screen systems such as the CTS-1000 and CTS-500 do not include a projector but can display the auxiliary video as a Presentation-in-Picture (PIP) image within the primary display. In this case, the PIP video is passed over the same HDMI cable that the primary display is attached to.
- Optionally, on any model system, the customer can choose to purchase auxiliary displays, mounted either above the center display or off to the left or right sides of the system. In this case, the customer can use the Cisco TelePresence Auxiliary Expansion Box, which acts as a 1:3 HDMI splitter, with one HDMI connection from the center (primary) codec and three HDMI outputs to the projector and auxiliary displays.
Network Connectivity
For the system to be standards-compliant with current networking methodologies and protocols, Cisco needed to design a way to make this entire system, with its multiple codecs and attached components, to appear as a single IP address on the network. To achieve this, the system leverages private, nonroutable RFC 1918 IP addresses between the primary and secondary codecs, between the codecs and their cameras, between the primary codec and the document camera, and so on. The primary codec, in turn, attaches to the upstream Ethernet LAN through a 1000Base-T Gigabit Ethernet cable and can obtain an IP address dynamically through Dynamic Host Configuration Protocol (DHCP) or use a statically assigned IP address. Therefore, the entire system uses a single Gigabit Ethernet port with a single Media Access Control (MAC) address and a single IP address.
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