CD player in 1970. Following litigation, Sony and Philips licensed Russell's patents (then held by a Canadian company, Optical Recording Corp.) in the 1980s. The Compact Disc is an evolution of LaserDisc technology, where a focused laser beam is used that enables the high information density required for high-quality digital audio signals. Prototypes were developed by Philips and Sony independently in the late 1970s. In 1979, Sony and Philips set up a joint task force of engineers to design a new digital audio disc. After a year of experimentation and discussion, the "Red Book" CD-DA standard was published in 1980. After their
WARP-CD on channel 20. The station, previously WARP-CA, began broadcasting a digital-only signal in late 2009. WARP-CA's call sign suffix (CA for Class A Low Power) was changed to WARP-CD (Class A Digital) automatically upon grant of WARP-CA's digital license in late 2009. WARP-CD currently broadcasts four channels of standard definition digital TV: 20.1, 20.2, 20.3 and 20.4. Longtime owner Randolph Weigner (who controls Sunshine Broadcasting Company) sold WARP, along with sister station WPHA-CD in Philadelphia, to LocusPoint Networks in November 2012. The deal made WARP a sister station to WSVT-LD, which LocusPoint acquired a month later. WARP-CD WARP-CD is a