There are basically four digital technologies currently available for private radio communications system use.  They are 
as follows:

APCO-25 (C4FM and CQPSK)

More commonly known as P25, this is the digital standard selected by U.S. Government agencies and presumed by many to be the platform best suited for all public safety users.  The purpose of P25 was and is to provide a common platform offering the highest level of interoperability while simultaneously addressing the need to move to narrow frequency channel spacing.  One of the best overviews of P25 has been prepared by Aeroflex, a test equipment manufacturer offering equipment for the servicing of P25 equipment.  For additional information, click here.  Technically, this is known as C4FM, compatible four-level frequency modulation) in a 12.5 kHz channel or CQPSK, compatible quadrature phase shift keying) in a 6.25 kHz channel (commonly known as Phase 2).  More information is available by clicking here.

FDMA (4 Level FSK)

More commonly known as NXDN, FDMA is a new commercial digital standard jointly developed by ICOM and Kenwood to provide the ability for a radio to function in either a digital or analog mode at 12.5 kHz, or 6.25 kHz.  Technically known as Frequency Division Multiple Access (4 level FSK), it is currently the most flexible and affordable platform available for VHF or UHF systems.  ICOM FDMA products (known and IDAS) are capable of incorporating a low cost "range extending receiver" to increase talk-back power from portable in remote areas, a feature not currently available with other digital system technology. Additional information is available by clicking here.

FHSS (Frequency Hopping Spread Spectrum)

FHSS is the platform used in the Motorola DTR 900 MHz on site portable radios.  This technology was actually invented by Hedy Lamarr, a 1940's movie star and U.S. Government secret agent. Click here for more information. The only competition Motorola ever had in the USA was from a company called Tri-Square (apparently no longer in business. FHSS technology is limited to portables with no more than one watt of power which has limited growth in the industrial sector.  It is unacceptable to public safety users.  FHSS is the technology of choice for cordless phones and has become a defacto standard for today's Wireless Local Areas Networks (LANS) as well as cellular phones operating at 900 MHz, 2.4, and the 5 GHz range.  

TDMA (Time Division Multiple Access)

More commonly known as DMR (Digital Mobile Radio), TDMA has been around for a long time in the cellular industry although most advanced cellular systems are evolving from GSM or CDMA to LTE technology.  Variations of TDMA are used in the popular Hytera and MotoTRBO radios.  DMR is the most popular of all the digital technologies, based on features, functions, and cost.  The Hytera models are capable of small system (2 channel) trunking with no special infrastructure required. Additional information is available by clicking here.

There are two emerging digital technologies worth noting although both are primarily limited to large scale users (wide area networks used by government agencies and utilities).  The one with the greatest potential for private networks is a mature European technology known as TETRA.  Hytera is offering TETRA products in the USA at this time.  The other system, commonly known as LTE is the platform used by the new generation of smart phones and is the foundation for a private public safety network being planned for large scale nationwide interoperability.

If you have additional questions, we are as near as your phone, PC, or fax. Thanks for visiting with us.  We look forward 
to serving you!   

The Falcon Team
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