and receiver is too great for the signal to travel between the two without being boosted along the way. Radio signals, as they travel through free space, are attenuated; their power is gradually lost. Thus repeaters are needed to interpret the original signal and amplify it. They also often amplify background noise and interference in the process. reproducing spot In television broadcasting, images are sent as a series of signals that describe a series of scan lines. A black and white television receiver captures these signals and reproduces the image on the screen using a reproducing spotthat writes to the screen, varying in intensity in accordance with the instantaneous amplitude variations of the received signal. Request in Progress H.323v3 feature that allows the receiver of a request to Message specify, when a message can not be processed before the initial timeout value expires, that a new timeout value should be applied. resolution The ability of an optical or video system to produce separate images of objects very close together and, hence, to reproduce fine detail. retrace The return of an electron beam to its starting place to prepare for sending a new field of information. retrace interval The process of moving a scan line back to the left-most position in order to begin a new scan. Video Communication: the Whole Picture Radio frequency. Electromagnetic signals that travel from radios or other sources through free space. A designator used to name one of the color signals in the color difference video signal, with a formula of .70R, -.59G, -11G. Radio frequency interference. Often manifests in television signals as vertical bars moving slowly across a picture. It can also take the form of diagonal or vertical lines or a pattern of horizontal bars. Red, green, blue. Color television signals are oriented as three separate pictures: red, green, and blue. Systems can merge them or, for maximum quality, leave segregated as component video signals. See Router Information Protocol See Request in Progress Messa