Why switch to a DMR simulcast solution

DMR simulcast for large-scale networks

In large-scale communication networks — particularly in highway environments — reliability, continuous coverage, and efficient spectrum use are non-negotiable. DMR simulcast solutions address these requirements better than conventional multi-site DMR systems: all repeaters transmit on the same frequency in a synchronized manner, and the user experiences a single, seamless network.

How simulcast works

In a simulcast system, multiple repeaters simultaneously transmit the same signal on the same frequency pair. Synchronization uses a common time reference — typically GPS — which aligns every site's transmission to the microsecond.

The result: users traveling across the network never change channel, never experience a site handover, and never hear audio gaps. This is critical on highways, where vehicles cover tens of kilometers through the coverage areas of many repeaters.

Technical advantages

• Continuous coverage — the signal is constant over long distances, with no manual frequency changes or channel scanning required by terminals.
• Spectral efficiency — a single frequency pair serves the entire network, regardless of the number of repeaters: a direct saving on spectrum license fees.
• Scalability — coverage expands by adding repeaters, all synchronized to the same time reference.
• Fewer dead zones — in areas covered by multiple sites, signals overlap and reinforce each other, reducing uncovered spots compared to non-simulcast alternatives.

Dual mode: analog and digital

DMR simulcast systems handle both digital and analog signals on a single antenna, switching automatically based on the incoming signal type. Where an IP backbone is unavailable, sites can interconnect via radio (UHF/VHF): this mixed IP + RF linking network reduces capital costs and makes simulcast viable even in terrain without line-of-sight between sites.

Simulcast vs. conventional multi-site

In conventional multi-site systems, each repeater transmits on a different frequency. Automatic roaming handles the handover between sites, but the switch can introduce brief audio interruptions and requires more complex frequency planning.

In simulcast systems, all repeaters transmit on the same frequency: coverage is continuous, with no site handovers or interruptions during travel, and a single frequency pair for the entire network. For large, geographically distributed networks — highways, tunnels, valleys — this is the most reliable and cost-effective solution over the long term.

Antenna diversity reception

Teleproject simulcast solutions implement diversity reception: the receiver combines multiple copies of the same signal captured by separate antennas, each subject to independent fading. The result is better receive sensitivity, wider coverage area, and more stable links even with low-power portable terminals.

Redundancy and reliability

Simulcast networks built by Teleproject include redundancy systems: backup units take over automatically on failure, keeping the network running without interruption in critical scenarios. The use of Linux-based systems further increases platform reliability and flexibility.

Teleproject field experience

Teleproject has built one of the largest DMR simulcast networks in Italy: more than 40 synchronized repeaters, over 400 km of highways covered, and more than 25 tunnels. Network users communicate without interruption along the entire route — inside tunnels and on viaducts — without ever changing channel.