on-air feed, and use the VITS to detect and troubleshoot problems in on-air transmission. Sync pulse generator A sync pulse generator (SPG) is a special type of generator which produces synchronization signals, with a high level of stability and accuracy. These devices are used to provide a master timing source for a video facility. The output of an SPG will typically be in one of several forms, depending on the needs of the facility: A continuous wave signal In standard-definition applications, a bi-level sync signal, often with a colorburst signal in facilities that have analog equipment. Typically, this is either in NTSC or PAL format. As the resulting signal is usually indistinguishable from an all-black television signal of the same format, this sort of reference is commonly known as black or black burst. In some high-definition applications, a 'tri-level sync' signal is used instead. This signal is virtually identical to the synchronization signal used in component analogue video (CAV); and is similar to the synchronization signals used in VGA (the main difference being, in VGA the horizontal and vertical syncs are carried on different wires; whereas TLS signals include both H and V syncs). Logo inserters Logo inserters are devices used to insert a television station's logo, or other fixed graphics, into a live television signal. Often called a "Bug Generator." See also Video display controller Philips PM5540 Telefunken FuBK ETP-1 Test card References External links Tektronix, Inc.A Guide to Digital Television Systems and Measurements Tektronix, Inc. NTSC Systems Television Measurements Tektronix, Inc. PAL Systems Television Measurements Video Products, Inc. Usage of Video Test Pattern Generator Philips TV Measuring Equipment, 1980 Film and video technology Electronic test equipment