Phonevision

Lore & Background

Zenith had experimented with pay television as early as 1931, believing advertising alone could not sustain television broadcasting. The company originally occupied television channel 1 in Chicago starting on February 2, 1939, when W9XZV went on the air, one of America's first non-mechanical television stations. In 1947, Zenith announced a perfected pay television system and selected the name "Phonevision." In 1950, the experimental station moved to the Field Building and became KS2XBS. In July 1953, Zenith was forced to shut down KS2XBS when WBBM-TV was moved from channel 4 to channel 2 by the FCC. The transmitter was later donated to Chicago's first educational station, WTTW. In 1954, Zenith resumed testing in the eastern United States on WOR-TV in New York City and later negotiated foreign contracts in Australia and New Zealand. The system was operational on station WHCT in Hartford, Connecticut, for at least five years, ending early in 1968; the station ran conventional programming during the day and Phonevision-encoded programming in the evening.

Reader's Guide

Phonevision's significance lies in its pioneering role in subscription television, a concept that would later become widespread through cable and satellite services. The system required viewers to purchase a descrambler unit that connected to the television's antenna leads and the telephone line. To view a movie, a customer would call the Phonevision operator, who added them to a queue; a signal sent via phone lines allowed the box to descramble the video and audio. At the end of the month, viewers were billed on their regular telephone bill. The Theatre Owners of America called the service a monumental flop, but Zenith president Eugene F. McDonald claimed it was a roaring success. Among the first 300 test households, only about 18 percent had seen the films in theaters, and 92 percent reported they would prefer to watch films at home. A major limitation was that the system could not broadcast color, as the delay line switching disrupted the phase lock needed for NTSC color. This limitation, along with the FCC's authorization of subscription programming in 1969, contributed to the system's demise.

Did You Know?

• Phonevision scrambled video by switching a delay line in and out, chopping the picture into slats and shifting half of them to the right.
• Audio was scrambled using frequency inversion, shifting the spectrum up 2.625 kHz.
• Some of Zenith's 1951 model TV sets included a special connector for Phonevision and an owner's manual section explaining the concept.
• The system could not broadcast color because the delay line switching disrupted the 3.58 MHz phase lock needed for NTSC color.