Are you ready for narrowbanding? Understanding the details

The Federal Communications Commission has rewritten Part 90 of the rules governing the operations of land mobile radio systems to reflect the narrowbanding changes. It has also set deadlines for manufacturers to develop equipment that is capable of operating on these frequencies. Licensees are also required to modify their systems to narrowband operation or replace older equipment to meet the revised Part 90 standards.

Deadlines are arriving

In most metropolitan and some rural areas across the country, VHF and UHF spectrums are becoming increasingly crowded as more public safety and commercial enterprises adopt wireless land mobile radio. The congestion is threatening to saturate the spectrum and create dangerously high interference levels that impede reliable communications.

In the 1990s, the FCC gave the land mobile industry and user community notice of its intent to increase spectrum availability by reducing channel bandwidth. This lead time allowed users to modify systems and obtain narrowband-capable equipment. Although the FCC has modified its orders and deadlines several times, two critical deadlines still exist:

January 1, 2011: New systems

All applications to implement new systems on Part 90 frequencies between 150 MHz up to and including 512 MHz must employ technologies that meet one of the following:

• Operate at 12.5 kHz (11.25 kHz occupied bandwidth)
• Provide one voice path per 12.5 kHz of occupied bandwidth
• Provide a data rate of 4,800 bps per 6.25 kHz of bandwidth occupied

Any new system being constructed should be designed to operate at 12.5 kHz or less channel spacing.

January 1, 2013: Modifications to existing systems

All applications seeking modifications to existing systems must employ equipment and technologies that do one of the following:

• Operate at 12.5 kHz (11.25 kHz occupied bandwidth)
• Employ a technology that provides one voice path per 12.5 kHz of occupied bandwidth
• Provide a data rate of 4,800 bps per 6.25 kHz of bandwidth occupied

These systems may operate at 25 kHz bandwidth until this deadline.

Narrowbanding deadline

All incumbent Part 90 systems operating on frequencies between 150 MHz up to and including 512 MHz must meet one of the following:

• Operate at 12.5 kHz (11.25 kHz occupied bandwidth)
• Employ a technology that provides one voice path per 12.5 kHz of occupied bandwidth
• Provides a data rate of 4,800 bps per 6.25 kHz of bandwidth occupied

While some companies and public safety entities have begun to install new or modify existing equipment, many others have not. There’s still time to meet 2013 deadline requirements, but only if organizations begin immediately.

Preparation — A narrowbanding checklist

Preparing for narrowbanding requires thoughtful analysis of several operations, logistics and finance considerations.

Key issues to review:

• Equipment inventory
• Identify the specific types of equipment that are used in the community, including first responder pagers
• Confirm the manufacturers of the equipment
• Determine what equipment needs to be replaced, updated and what can be reprogrammed
• Ensure your equipment is capable of 7.5 kHz channel spacing at VHF or 12.5 kHz channel spacing at UHF
• Review equipment infrastructure, including dispatch consoles, base stations, satellite receivers and control stations. (In many cases, this equipment cannot be reprogrammed to narrowband operation and should be replaced with current production equipment. Field retrofits of this equipment are not recommended, as unapproved retrofits are a violation of FCC rules.)
• Check and reset audio and paging tone levels

Other equipment-related issues to consider: