Synchronous FM

Call it sync FM, synchronized FM Broadcast, synchronized/synchronous FM transmitter, time synchronous FM transmission/playout, single frequency FM/radio network:

A FM SFN (Single Frequency Network) is a broadcasting network where different FM-transmitters are sending out the audio on the same frequency and absolutely time synchronized. Digital broadcast networks like DVB-T/T2 as well as analog AM and FM radio broadcast networks can operate in this manner. The advantage of a SFN is the efficient utilization of the frequency spectrum, allowing a higher number of radio and TV programs to be transmitted. An example of this technology is a frequency- and time synchronized FM transmitter chain along highways.

One challenge for the perfect function of such a system is the very high accuracy in time synchronization (audio quality, interference) of the signal to be transmitted.

Broadcaster worldwide are using different types of content distribution (ASI, E1, satellite, IP) to improve redundancy, to be more variable and to save costs.

Any transmission feed to the FM transmitter, even the well synchronized feed via E1, produces different delays. Unsteady packet delays within an IP-feed (Jitter) or a Satellite feed might lead to even higher delay which makes the different FM cell synchronization much more complicated.

The 2wcom Systems solution enables your signal to be exactly synchronized within the contribution path of the FM-SFN network.

You simply need to add an additional 2wcom Systems Inserter in your transmission feed and to provide 1pps signals at all stations. Our professional Receiver/Decoder is analyzing the signals and perfectly synchronizes the Audio signal to the Stereo and RDS Encoder. It does not make any difference what type of distribution is being used either E1, IP or satellite or if any one of these feeds are being selected for any backup purposes. This is absolutely basic for SFN transmission because the pilot signal already has to be synchronized very exactly.

Further steps will be the synchronization of the Encoders and Transmitters that broadcast the signal at the end.

  • Realization of FM SFN networks with existing, analogue FM technique
  • Minimal hardware requirements (1 Inserter for uplink, x Receiver/Decoder)
  • Perfect synchronization, precisely down to the μs
  • Automatic adjustment of runtime differences, jitter etc.
  • Supports different types of distribution (ASI, E1, Satellite, IP)