Library items tagged: introduction

To reduce echoes caused by transmission delays, special devices known as “Echo Cancellers” are used. These devices when operating efficiently can almost eliminate all traces of echo during a conference. Room acoustics and microphone positions also affect the level of echo. If a microphone is moved or its sensitivity is altered during the conference, echo could be introduced until the echo canceller has realigned itself to the new environment.

Videoconferencing is a form of television so the guidelines for appearing on television are relevant. Because videoconferencing uses a reduced quality network link to keep costs down some other limitations are also introduced. Television cameras can only handle a very limited range of contrast so wear clothes in pastel shades and plain weaves. Strong saturated colours and white shirts are not recommended. Within a videoconference, faces are the focal point, so clothing must not pre-dominate the image. Avoid clothes that are brightly coloured or with a distinctive pattern.

Another option with Multipoint working is “Chairman Control” where all sites receive pictures from the Chair site alone. The Chair site will see images from the remote site currently speaking. All sites receive all sound. 

Conferencing between two sites is termed “Point to Point” and is the most frequently used method. It only requires equipment at each site and the network of choice. If more than two sites require a simultaneous conference, this is termed “Multipoint” conferencing, and an additional specialised piece of equipment is required, called a “Multipoint Control Unit” or MCU. Some videoconferencing CODECs can support limited multipoint working (e.g. up to 4 sites). Generally, MCU’s are very expensive and are rented from service providers just for the duration of a conference.