ontext of what the signal will be used for and how it will be judged for acceptance or rejection when it is decom- pressed. An equally important consideration is how many times the signal will undergo lossy compression and decompression before being used (displayed or listened to). See Encoding and Decoding. DACS Digital Access and Cross Connect Switch is a network elem- ent used mostly by Telecom service providers to groom segments of transmission bandwidth. DACS typically fits between the trans- mission facility and switching or routing equipment. So-called Private Lines are provisioned using DACS to aggregate and parti- tion off sub-T1 (also called Fractional T1), T1, E1, E3, or DS3 band- width between two circuit endpoints to make up the Private Line. May also be labeled a Slow Switch. Digital Digital is a common term for either signals or information in digital form or the transport medium-tape, CD, or any network capable of carrying the digital signal. A digital waveform or volt- age only has two states-on or off; the signal is either there or it's not there. It's often said to be a 1 or a 0 (i.e., something or nothing). The timing associated with the transition from one state to the other can be synchronized with a clocking signal-synchronous or if it's not it's said to be asynchronous. DVB-ASI Digital Video Broadcasting-Asynchronous Serial Inter- face is an increasingly popular interface selected by designers for use in digital television facilities. Broadcast engineers with a good understanding of SMPTE-259 like it because it's a lot like what they PRACTICAL IP AND TELECOM FOR BROADCAST ENGINEERING AND OPERATIONS already know. Communications engineers like it because it's simi- lar to E3, DS3, and STM1. What's to like? BNC Connectors and 8281 coax, for starters. Is this convergence at last? Facility A facility is generally, something physical, such as a build- ing with equipment and amenities used to produce content or provide service. Examples include studio facility or transmission facility in the broa