Shaping radio today and tomorrow

August 1, 2002


Do You Remember?

The Time Tunnel digital audio delay system offered a broadcast-quality, six-second audio delay that used a digital memory system to provide consistent audio reproduction. Unlike tape delay systems, it had no moving parts to wear, no preventative maintenance was necessary and the performance did not degrade with time.

The Time Tunnel was offered in two models: the TDG-1 with a 15kHz bandwidth and the TDG-2 with a 7.5kHz bandwidth. Both models created a frequency response flat within 0.25dB and a total harmonic distortion of less than 0.5 percent. They offered an operating range of greater than 66dB with a clipping level of 12dB and a system signal-to-noise ratio of greater than 80dB.


That was then

This is the radio transmitter room of KPO in Hale's Department Store, San Francisco, in 1925. Shown in the foreground is the Western Electric 1kW model 6A transmitter. In the background are marble-faced electrical control panels, which at the time were the only ones of their kind in the country.

The KPO employee inspecting the transmitter is probably Claire Morrison, KPO's first full-time announcer. The transmitter was a newer design and unlike earlier transmitters, it was capable of 100 percent modulation. By this time, most stations were assigned to their own frequencies and transmitted for significant portions of the day. KPO is now KNBR, San Francisco. Photo courtesy of Bill Ruck, KNBR.


Sample and Hold
A look at the technology shaping radio
What do talk-radio listeners do while listening to the radio?

Source: Scarborough Research, Release 2 2001



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