Pittsburgh is the cradle of radio broadcasting: the site of the first commercial radio broadcast and first radio station -- KDKA-AM -- and the base for some of the earliest research in radio transmission.

In 1906, Reginald Fessenden successfully transmitted a test broadcast across the Atlantic Ocean, which included him talking, playing violin and singing a Christmas carol -- an event that opened the door for the 20th-century medium of radio.

The University of Pittsburgh is marking the 100th anniversary of Fessenden's broadcast with a symposium, "The Birth of Radio and the Pitt Connection," from 8:30 a.m. to noon tomorrow at Benedum Hall Auditorium, O'Hara and Thackery streets, Oakland.

An inventor and a technological pioneer, Fessenden did groundbreaking work in early broadcasting technology, using high-frequency electromagnetic waves to transmit the human voice. Much of that research was done while he was chairman of the electrical engineering department at the University of Pittsburgh, then known as Western University of Pennsylvania.

The symposium will focus on both the past and future of radio. A panel discussion on the history of radio will include Charles Reichblum, host of the weekly "Dr. Knowledge" on KDKA; Rick Harris, who is one of the principals behind the drive to establish a Pittsburgh-based broadcasting history museum; G. Alec Stewart, Pitt's Honors College dean and amateur radio enthusiast; and Marlin Mickle, professor of Electrical and Computer Engineering and Telecommunications at Pitt.

The second part of the program will look at the future of the medium, with Gerald Youngblood, CEO of FlexRadio Systems, a company that has developed software-based radios. The leading-edge technology uses software to modulate signals, and the devices are now used by amateur radio operators.

-- Adrian McCoy

Vargas returns to TV

Following a 12-week maternity leave, Elizabeth Vargas will return as co-host of ABC's "20/20" at 10 tonight with a feature about the plight of working mothers. Vargas had stepped down as co-anchor of ABC's World News Tonight during her pregnancy.

Among the featured moms will be Pittsburgh's Michelle Porter, a mother of two who works full time, just completed her undergraduate degree and serves as PTO president at her children's school, Phillips Elementary on the South Side. Porter, and other local volunteers, will be honored this month with the Volunteer Recognition Award, presented by PNC Bank and South Side Local Development Co.

-- Local and wire reports