Thursday, February 17, 2005

Synchronizing FM Radio Stations With T1 Lines

In the world of radio broadcasting there are large, medium and small stations. The large stations are generally associated with high power and major market coverage. Medium and smaller stations may completely serve smaller communities or partially cover larger metro areas. Big stations mean large audiences and big bucks. But there are only a few available to go around. What would you think of building a huge FM station by combining a bunch of small stations?

The latest digital technology is making it possible to synchronize two or more stations on the same frequency transmitting the same program so that you won't notice when your car radio moves from one station's coverage to another. This is similar to cellular phone service where the radio cells seamlessly hand off your phone call from one to the other, ensuring that you always get the strongest signal possible.

Harris Broadcast Communications has a system called Intraplex SynchroCast that uses GPS receivers and T1 telecom lines to tie stations together so they act like one larger and more powerful transmitter. The system uses Global Positioning System (GPS) receivers at each transmitter to precisely synchronize the carrier and stereo pilot signals. That puts the transmitted signals in phase rather than some random phasing that you would notice when you are situated between stations.

The other important part of this system is using T1 lines to transmit the station audio digitally between studio and transmitters. That's done by stations anyway because digital studio to transmitter links preserve audio quality over a distance of miles. The new wrinkle is to install an additional GPS receiver at the studio and send its timing signals along with the audio to each transmitter.

What this does is let the SynchroCast system determine the time delay of the audio program coming from the studio to each transmitter. Chances are they are different because the transmitters are not the same distance from the studio. SynchroCast adjusts a small digital time delay for each program signal so that they are transmitted from each antenna at exactly the same time. The programming will then arrive at the point between stations correctly in phase so you won't be able to tell when your radio switches from station A to station B.

Clever, right? With an arrangement like this, a broadcast company can buy up smaller stations on the same frequency that ring a metro area or are located along an interstate highway. Listeners will be able to hear the programming much further than if they had to switch stations to find the same program. They'll also avoid the distortion that you get when stations on the same channel carry the same program but are not synchronized.

If you are in the radio, television or audio network field and are interested in T1 lines for audio transport, let T1 Rex help you get the T1 links you need at the best prices.

Click to check pricing and features or get support from a Telarus product specialist.

Follow Telexplainer on Twitter