T1 Lines for Audio Transport

AM & FM stations and radio networks started using telephone lines to transport program audio and remote broadcasts back in the 1920's. Even today some stations still rely on pairs of equalized telephone lines as audio links from studios downtown to transmitters out in the boonies. The technology trend of the last few decades, though, has seen stations moving to 950 MHz band studio-transmitter links (STL) and satellite network downlinks. In the digital audio age, why would anyone think of going back to telephone lines to send audio? After all, telephone lines aren't the first thing that comes to mind in high performance audio technology.

The new twist is using digital T1 lines to send digital audio from point to point. It's actually a natural fit. The 1.5 MHz bandwidth of a T1 line using two pairs of ordinary copper phone line is wide enough to send FM stereo and digital radio programs as far as you like. The audio quality doesn't degrade because the digital pulses are regenerated as required along the path. What's more, T1 lines are bi-directional and full duplex. That means you can send remote pickup programs, transmitter data, telephone lines or satellite audio in the opposite direction at the same time.

Equalized analog phone lines are getting expensive and hard to come by in some areas. 950 MHz STL frequencies have become crowded and they need direct line of site access to work. Satellite uplink/downlink systems are very expensive. At the same time, T1 line service is getting cheaper and is readily available nearly everywhere. You don't need line of site transmissions or locations near each other. It's a phone line!

If you are interested in exploring more about broadcast quality audio transmission over T1 lines, you can find the equipment at Harris Intraplex, QEI CAT-LINK and Moseley Starlink. You can get the latest prices on T1 line service here.