MEMORY LANE: AT & T’s coaxial creation

Thu, 07/31/2008 - 8:15pm
Stewart Schley, Media & technology writer, Englewood, Colo.

The company that invented coaxial cable doesn’t even bother to use the stuff

AT&T’s U-verse, the IP-based wireline video service that passes 9 million U.S. homes, depends on a latticework of optical fiber and twisted-pair phone lines to pass television signals along to its customers. But in relaying the bit streams of digital video across its incumbent last-mile access network, AT&T eschews an essential conduit that it helped bring to life.

Stewart SchleyUnited States Patent 1,835,031 was issued to AT&T’s Bell Telephone Laboratories by the U.S. Patent and Trademark office on Dec. 8, 1931, at least 15 years before the first community antenna TV systems – precursors of today’s cable industry – came to be. The patent went specifically to two AT&T electrical engineers. Lloyd Espenschied was a Missouri-born inventor who joined AT&T in 1910 and remained there through his retirement in 1954. With colleague Herman Affel, Espenschied authored an American Institute of Electrical Engineers paper on wideband coaxial cable that enthused over the possibility of using coax to carry simultaneous telephone conversations with little signal loss or interference. The two theorized that by confining the electromagnetic field that would carry signals to the space between inner and outer conductors, coaxial cable could provide excellent shielding from interference, while offering more capacity than prevailing wired transmission lines.

AT&T was interested in the medium of coax mainly as an instrument to help accommodate the rising flow of telephone calls its burgeoning phone network was carrying. But the company also had designs on playing a role in the new medium of television, and believed coax might be just the conduit to shuttle television between locations. AT&T installed its first coaxial cable line between New York and Philadelphia in 1936, and five years later introduced the medium in a commercial deployment, connecting facilities in Minneapolis and Stevens Point, Wis. The coaxial link AT&T established was able to carry 480 concurrent telephone conversations, “or one television program,” notes a corporate timeline published by AT&T online.

On the television side, AT&T’s main interest revolved around distributing programs from origination points to distant reception and transmission sites. The company had wowed a group of journalists in 1927 when it demonstrated how its phone network could be used to transmit a live television program featuring President Herbert Hoover from Washington, D.C. to New York. In 1948, AT&T introduced a video delivery network that connected TV stations in Boston and St. Louis over coaxial cable and microwave facilities.

But AT&T never seriously contemplated immersion in the laborious task of stringing short strands of coaxial cable among homes and neighborhoods in small-town America. Instead, a handful of local businesspeople in Pennsylvania, Oregon and elsewhere busied themselves by making use of the transmission medium AT&T had developed to build shared TV-delivery systems. Those “CATV” networks began slowly to gain momentum as entrepreneurs realized they could make money by charging customers for connections to their community-antenna systems.

By the 1970s, the coaxial cable technology Espenschied and Affel invented was purely a behind-the-scenes conduit for AT&T’s widening telephone networks. And within a short time it would be supplanted by more efficient and higher-capacity distribution technologies of satellite communications and optical fiber.

AT&T largely sat on the video sidelines as the cable industry rose to become a significant force in telecommunications, save for a bruising political battle over the rights to attach cable lines to utility poles. The company’s 1999 acquisition of Tele-Communications Inc. and MediaOne vaulted it into a category that AT&T had been instrumental in enabling, but AT&T’s presence was short-lived, culminating with the sale of its cable properties to Comcast Corp. in 2002.

Today, AT&T is competing fiercely with cable operators to sell phone service, broadband data connections and video services to consumers. The platform it’s using marries high-capacity fiber with copper phone lines – the building blocks of the modern phone network. It offers many of the same TV channels cable operators carry. It delivers high-speed Internet services much like those offered by cable. Like cable TV, it features add-on goodies like digital video recorders, video-on-demand and high-definition television transmission.

But the missing ingredient in AT&T’s U-verse network produces one of the grand ironies of the competitive video delivery marketplace: The company that invented coaxial cable doesn’t even bother to use the stuff for its own television network. The question yet to be answered – for now U-verse remains a nascent entrant on the video scene, with fewer than 500,000 customers nationwide – is whether that matters.



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