Palomar College Television

PCTV

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Technical Information

A basic videoconferencing system consists of a videoconference codec, a video monitor, camera, one or more microphones and an audio speaker. We can include additional peripherals to the system to enhance collaboration, such as a document camera, computer, videotape or disc player, recorder and external video and audio sources. You connect with the distant site by dialing into their videoconferencing system similar to dialing a telephone. Videoconference connections use ISDN (Integrated Services Digital Network), Video IP (Internet Protocol) or a dedicated circuit, such as T-1. A T-1 line is a dedicated service between two sites. ISDN is an economical solution for high-quality videoconferencing. ISDN works over regular copper telephone lines transmits at a minimum of 128 Kbps per line and provides dedicated bandwidth for smooth audio and video (15-30 frames per second). ISDN videoconferencing systems adhere to H.320 standards while Video IP adheres to H.323 standards. This means that any standards-compliant system can connect to any other H.320 or H.323 standards-compliant videoconferencing system in the world. Video IP is part of the world’s data network. The State’s internet protocol backbone system managed by CENIC provides high speed connectivity to the Cal State University Chancellor's Office, California Community Colleges and any other site throughout the world. The established video call rate or speed for videoconferences is 384 Kbps up to 3Mbps.

There are two types of videoconference meetings: point-to-point, a conference between two sites, and multipoint, a conference between three or more sites. To participate in a point-to-point videoconference, one site dials the other site's videophone number or internet protocol (IP) address. Each site continuously sees and hears each other during a conference call. In a multipoint conference, each site dials a videophone number or IP address to a video bridge at one site, or connects via a video bridge service company for a fee. Newer videoconferencing systems have built-in video bridges that allow you to conference with multiple distant sites just as you would in a point-to-point conference call. You can even add other sites at anytime during the conference. These newer videoconferencing systems eliminate the need to schedule and pay fees for time on a video bridge.

There are two types of multipoint videoconference calls: voice-activated and continuous presence. You are able to see and hear one or more sites. A voice-activated conference call will allow you to conference with multiple distant sites. The video switches between sites only when someone speaks. Everyone sees only one site on the video monitor in a voice-activated conference call. During a voice-activated conference call, if no one speaks at a site, you will see only the person that last spoke. In a continuous presence conference, each site views in quadrants up to four sites simultaneously on the video monitor. If more than four sites are connected, one quadrant toggles between the remaining sites when someone activates the audio. An advantage of a continuous presence conference call is that multiple sites are always seen on the video monitor. Many of the new videoconferencing units support continuous presence.

At Palomar College you can connect to a distant site via ISDN or Video IP. We have the capability to provide voice activated or continuous presence, single and multi-point bridging capability. In addition we have access to the State’s CENIC network services including multi-point bridging. Click here to view some of State videoconference sites.

We welcome your questions and comments, please call 760-744-1150 ext. 2431, or send an e-mail to videoconference@palomar.edu