Are you ready for narrowbanding? Understanding the details

The Federal Communications Commission (FCC) has rewritten Part 90 of the rules governing the operations of land mobile radio systems. The Commission has also set deadlines for radio equipment manufacturers to develop equipment that is capable of operating...


The Project 25 Phase 2 standard, which is close to final approval, employs Time Division Multiple Access (TDMA) technology to create two simultaneous talk paths in a 12.5 kHz channel, thus meeting the 6.25 kHz equivalent requirement. Major vendors have committed to this standard and plan to have complete systems on the market by 2011. Phase 1 and Phase 2-capable portable and mobile radio equipment is now available.

  • Business, industrial and land transportation applications

Manufacturers have introduced several technologies targeted to non-public safety users with 6.25 kHz compliant systems. These digital systems use TDMA and Frequency Division Multiple Access (FDMA) to meet the 6.25 kHz requirement, and include competing technologies from the leading B/I/LT systems manufacturers:

  • MotoTrbo from Motorola — a two talk path TDMA solution operating on a 12.5 kHz channel.
  • NXDN Digital from Kenwood and ICOM — a single digital talk path FDMA solution operating on a 6.25 kHz channel.

Both systems are capable of 12.5 analog narrowband operations, as well as their respective 6.25 kHz equivalent proprietary digital formats.

Meeting the deadline

The narrowbanding process can seriously impact today’s VHF and UHF public safety and business/industrial licensee. Time is growing short. Licensees must begin the process immediately to determine the scope of work that is required on their system, obtain funding and plan the logistics, while maintaining service to the user agencies and ensure all licensing and operational details are met.

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