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TetraFlex® Compact Tetra Base Station from Resound Ltd


Resound Ltd is the Main UK Distributor for the TetraFlex® Compact Tetra Base Station which is manufactured by DAMM CS in Denmark.


The BS421 Compact Tetra Base Station is about the size of a briefcase and can be supplied for indoor or outdoor use.

Resound Ltd can advise on vehicle mounting or use in a vessel or aircraft with suitable antennas. A Transportable version is also available in a rugged waterproof carrying case.


  • Designed for the professional communications user

  • Compatible with the main manufacturers handportables

  • High reliability for Public safety and industrial use

  • Suitable for rapid deployment in Military operations




  • TetraFlex® is the smart business choice to make the leap from analogue to digital communications systems.

  • TetraFlex® is a complete single/dual carrier IP based system developed for single site operation that can handle voice and data communications. Multi-site operation available Q3 2007.

  • TetraFlex® is developed as a closed system ready to enable any organization to have instant, reliable, secure communications they can count on - in urban or rural applications

Leap from analogue to digital with TetraFlex®


  • TetraFlex® offers plug & play simplicity for easy set up and fast deployment

  • The unique TetraFlex® local network architecture is based on pure IP interfacing to connect base stations, dispatching work stations, network management facilities and even gateways for external voice and data systems

  • TetraFlex® has an Application Programming Interface (API)

  • TetraFlex® is designed for indoor or outdoor mounting

  • TetraFlex® is easy serviceable and has a very high MTBF

  • Best of all, TetraFlex® is small in size and weight – and ready for immediate installation and operation



Whether purchased or leased:

  • TetraFlex® offers an excellent price / performance ratio and is closely comparable with existing analogue system costs.

  • It is more cost effective when compared to other digital systems on the market offering the same capability.

  • And because the system is from DAMM Cellular Systems a proven leader in TETRA technology – you know you can count on it for excellent build quality, and reliability.

Resound will deliver a TetraFlex® turnkey solution




The TetraFlex® technology is based on:

  • Local Area Networks (LAN)

  • Wide Area Networks (WAN)

DAMM started to explore an IP approach based upon a few straightforward notions:

  • TETRA voice is made of data packets (TDMA slots)

  • A TETRA network is composed of radio relays exchanging voice data like clients in a client/server computer architecture, with the server regulating the destination of the data

The TetraFlex® local network architecture has been designed in such a way that all network elements use similar network interface

  • This allows considerable flexibility in terms of network element location (any element can be located at any place in the network) and

  • By local network expansion additional local network elements are treated as other clients with their own IP address


  • TetraFlex® is a complete TETRA digital communication system

  • TetraFlex® comprises a base station and a proven software solution



Nowadays practically every aspect of electronics uses digital technology - and wireless radio based communication systems are no exception

Even though analogue Mobile Radio communications will remain an available option for several years - the move to digital communications is rapidly increasing

So why is the world of Mobile Radio communications moving from analogue to digital? The answer is to compare the relative advantages and disadvantages of analogue and digital in the areas of:



  • Excellent voice quality (Low bitrate codecs are used (4Kbit/S)

  • Background noise is suppressed

  • Simplex and Full Duplex (telephone type) communication available

RF coverage

  • No particular difference in the RF coverage, compared to analogue systems

  • The good voice quality is lasting ”longer” in a digital system compared to the analogue system

Non-voice services

  • Typical digital system has a gross/net data rate of 8000 bit/s (after FEC)/4800 bit/s

  • For example MPT1327 analogue systems has a gross/net rate of 1200/600 bit/s


  • Good voice security against eavesdropping with scanners

  • Easier establishment of encryption facilities for higher security applications when needed


  • Similar system costs to directly comparable multi-channel systems


The TetraFlex® system comprises:


DAMM base station BS421 from Resound Ltd                                        DAMM System Controller SB421 from Resound Ltd

           DAMM base station BS421                                DAMM System Controller SB421


TetraFlex® software


Technical information

  • TX antenna output power 10W TETRA (lower setting as required)

  • Indoor or Outdoor / Tower mounting unit (minimized cable loss)

  • Integrated duplex filter

  • Full RX/TX operation on one single antenna

  • Dual receiver diversity on two antennas

  • Dual carrier and dual receiver diversity on two antennas

  • Power Supply -48V DC

  • 10/100Mbit/s Ethernet interface (including Voice over IP)

  • Protection category IP65

  • Synchronisation from internal source (single carrier) or by GPS receiver (dual carrier configuration)

  • Compliance to ETSI/TETRA specifications


Technical information

  • Based on DAMM Service Box SB421

  • Support for up to 2 DAMM BS421 base stations

  • Capable of serving additional dispatchers and NMWS

  • Pentium CPU and Microsoft XP inside

  • Built-in Ethernet switch

  • Internal -48V DC power supply

  • Built-in lightening protection

  • IP65 encapsulation

  • Easy installation

  • Optional internal battery back-up for up to 2 hours operation – further capacity is connectable

  • Optional redundant dual base configuration



Voice Services

  • Individual calls

  • Group call

Data Services

  • Circuit mode data

  • SDS

Other Services

  • Registration and deregistration

  • Group attachment

  • Push To Talk transmission management

  • Emergency call

  • Immediate entry

  • Energy economy mode

  • Secondary control channel

Supplementary Services

  • CLIP

  • CLIR

  • Talking Party Identification

  • Call Forwarding (unconditional)

  • Call Forwarding (on Busy)

  • Call forwarding (on no Reply)

  • Call Forwarding (on Not Reachable)

  • Access Priority

  • Priority Call

  • Late Entry

  • Pre-emptive Priority Call

  • Include call (Dispatcher)

  • Barring of Outgoing Call

  • Discrete Listening

  • Dynamic Group Number Assignment

  • Call Retention

  • PABX connectivity

  • Dispatcher connectivity

  • Base station fall back

Management Services

  • On queuing services

  • TetraFlex® System Timers

  • Call Duration Timer

  • Maximum Transmit timer

  • Transmit Activity Timer

  • Subscriber class information

Optional Services

Air Interface Encryption

  • Class 2, SCK

  • Class 3, DCK

  • TEA1

  • MS Authentication


TetraFlex® Network Management Centre provide you with:


Overview of your system

  • Overview of the architecture (stored in the central database)

  • Network configuration

  • Subscriber management

  • Subscriber definition

    • Class of service parameters,

    • Radio terminal subscriber parameters

    • Group Subscriber parameters

  • Subscriber invalidation

  • Display of call registrations (communication log book)

  • Dynamic Group Number Assignment

Open channel facility – as used in typical analogue systems
Fault reporting, (only with 3rd party SNMP manager installed)
List of alarms (only with 3rd party SNMP manager installed)




TetraFlex® SDS Gateway function provides you:

  • Support for ETS 300 392-2 [1] across the SDS Gateway connection

  • Transparent handling of SDS messages from originator to a SDS entity at the receiving destination in a SDS/TETRA network

The SDS gateway is invoked if:

  • A SDS service request is received from a TETRA Network to an address/SDS entity within the SDS network

  • A SDS service request has been received from the SDS network to be sent to a TETRA network user.


An Innovaphone gateway or a PABX supporting H323 must be installed, then:


TetraFlex® H323 gateway software provides you:

  • Communication between TETRA terminals and external IP Phones

  • Communication between the TetraFlex® and PSTN - vice versa

Types of supported gateway communication:

  • Individual full duplex calls between 1 Mobile User and 1 IP phone

  • Individual full duplex calls between Mobile User and the H323 gatekeeper

  • Group calls, half duplex, initiated by the IP Phone extension

Additional facilities for special purposes

  • Individual full duplex calls between Mobile Users - this can be used to carryout precise co-ordinated work requiring a continuous link


A powerful tool making it possible for a single operator to control the activity of the fleet of mobile radios within:

  • Voice dispatching

  • Data calls

  • Voice traffic monitoring

Dispatcher functions:

  • Call and queuing management

  • Standard calls

    • Emergency calls

    • Comm. with PABX/PSTN subscriber

    • Data calls

  • Voice communication monitoring

  • Call forwarding to other dispatcher

  • Handling of DGNA





Single carrier with H323 interface



Resound Ltd will be pleased to discuss any Digital or Analogue requirements you may have. Contact them now -


Resound Ltd
11 Anglo Business Park
Smeaton Close
HP19 8UP

Tel:    +44 (0)1296 330568
Fax:   +44 (0)1296 420159


Contact:  Coleen Allen (Director)





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