Professional infrastructure for digital mobile radio.

The Radio Activity Kairos repeater is an exceptionally innovative, compact and fully featured professional radio solution.


Based in Milan, Italy, Radio Activity has been at the forefront of DMR infrastructure development and manufacture for over 7 years. The first generation DMR infrastructure product has been deployed in significant multisite national networks across Europe, specifically meeting the needs of European spectrum requirements using simulcast. Radio Activity has been a Category 1 member of the DMR Association since 2007 and is a fully accredited DMR interoperability testing facility. Radio Activity has now focused all this knowledge and experience to develop and release their second generation DMR repeater, the Kairos. Kairos is an exceptionally innovative and scalable repeater platform which is the perfect building block for any DMR application, from simple standalone sites to complex nationwide systems.


The Radio Activity Kairos repeater is a 'software defined' radio in which all the mode modulation and filtering processes are achieved through Digital Signal Processing (DSP). This technique assures reliable and precise matching between the base stations and allows for a repeater that is exceptionally small and lightweight. This also provides a platform that is future proof; new protocols and standards can be implemented as a software upgrade. The design is based on a Linux core providing native IP interfacing in distributed IP networks.The radio platform has been designed to meet the most stringent specifications, making Kairos suitable for applications where radio frequency pollution is a known problem. Excellent resistance to interference coupled with software diversity reception, greatly improves usable coverage and ensures clarity of signal.



The repeater switches automatically between analogue and digital transmission according to the incoming signal type. This enables easy migration from analogue to digital in a large fleet without a complete fleet switch over.


Provides sophisticated network protocols required for professional multisite networks: IP linking and interfaces, Voting, Automatic Equalisation, Syncronisation Recovery, Precision Time Protocol (PTP) and Self-Calibration.


Allows the repeater to be used as an RF interconnect between sites where an IP backbone is not available and can be used to link channels in analogue, DMR and dual mode.


Included as standard,this is a signal reception technique based on the vectorial treatment of two or more incoming signals.It strongly enhances the received range by removing fade holes and other multipath issues.


Repeaters can be configured in 1+1 hot standby (main + standby) mode to provide system redundancy. Repeaters can also be setup as Backup Masters (a Slave repeater that automatically replaces a failed main Master, maintaining all the network functions). The LINUX platform allows a distributed implementation therefore increasing its flexibility and reliability.


Setup and network maintenance operations are simplified by use of a sophisticated remote monitoring and configuration tool. This also allows secure software upgrades,IP backbone diagnosis and an overview of the complete radio system. The Kairos also supports the SNMP protocol for direct reporting to a generic monitoring system.


Provides for direct connection to the radio network and extensive integration capabilities with software applications (e.g. control room consoles) and PABX systems.


The Kairos's innovative design provides for an extremely lightweight, compact and fanless repeater. The very low power consumption makes the Kairos well suited to off-grid sites, simplifying and reducing the cost of associated power sources.


The power supply input is protected from short circuit and under/ over/ reverse voltages. The RF power devices are protected from reverse power, over temperature and over current.


The example configurations below are available both in multicast and in simulcast solutions, all supporting dual mode analogue/digital modulation, IP or trigger base connected dispatchers and PABX patching.

DMR TDMA Repeater / Fixed Station

The Kairos supports the DMR Association two time slot TDMA modulation for both repeater and fixed link use.

IP Linked Repeater

Kairos supports IP connections between base stations to provide multi site hierarchical systems. The role of the repeater can be set as Master, Secondary Master, Slave or Backup Master. A Master manages up to 32 Slaves / Secondary Master.

RF Linked Repeater

A Kairos repeater can be configured as a"LAN extender" supporting RF narrow band connections between different sites.It is the perfect solution for very simple long-range links particularly where microwave is ruled out due to topographic limitations. Link traffic can either be a single analogue channel, DMR channel(both timeslots) or dual mode.


2RU 19" racks available for single or dual Kairos repeaters


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