Why deploy a Single Frequency Network (SFN)?

A Single Frequency Network (SFN) is a network of multiple transmitters that simultaneously broadcast the same signal on the same frequency. Radio broadcasters can greatly expand their coverage over wider areas by using the same frequency for all transmitters in a SFN, which optimizes the use of the spectrum and eliminates the necessity for multiple frequencies.

Highway Applications

On highways, smaller transmitters can be placed strategically to cover the entire road, providing a continuous listening experience for travelers. These transmitters work together to overlap coverage areas smoothly, extending reach without interruption. This setup minimizes interference, allowing for clear transmission of content. In both open and enclosed spaces, like tunnels, the SFN’s ability to keep the service uninterrupted ensures a consistent and reliable connection for the mobile audience, offering a stable and dependable broadcasting experience for radio stations.

Improved Coverage

Even when an FM transmitter is optimally located, there can still be opportunities to expand its coverage for a larger audience. Directional antenna patterns help but have limitations, and finding translator frequencies may become difficult. By employing co-channel transmitters at the network’s edges, SFNs facilitate the integration of extra transmitters to effectively fill coverage gaps in a seamless manner.

Synchronous FM by Nautel

Nautel delivers an efficient SFN solution by utilizing SPANFM (FM Head-end/encoder) to transport content synchronously to multiple SYNCFMs (FM decoders) strategically positioned at each radio transmitter within the SFN network.


As the dedicated head-end/encoder solution for single-frequency FM networks, SPANFM excels in audio and RDS data encoding, incorporating timestamp synchronization. This advanced solution offers exceptional portability across various industrial PC platforms, including 1RU, 2RU and 4RU systems.

As a flexible and compact all-in-one box solution, SPANFM demonstrates its versatility in encoding and multiplexing capabilities. It operates with intuitive graphical user interfaces and a straightforward architecture, equipped with integrated GPS (optional) for enhanced precision. SPANFM’s 1+1 redundancy ensures uninterrupted broadcasting reliability, setting high standards for performance.


SYNCFM is the synchronous FM decoder that guarantees the synchronization of audio, MPX, or direct RF for FM transmitters or amplifiers. Adaptable in various applications, SYNCFM interfaces effortlessly with amplifiers (RF output) or FM transmitters (audio or MPX output).

SPANFM, combined with SYNCFM, creates an IP-based Distribution Network, ensuring efficient data delivery through optimized IP bit rates using MPX over IP or MPEG 1 layer 2 encoding. SYNCFM achieves exceptionally precise synchronization, with accuracy levels of less than 1 μs.