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:

  • Any equipment certified for manufacture or import since Feb. 1, 1997, must be able to be retuned to narrow bandwidth. Some VHF equipment, however, has been found not to be programmable on every 7.5 kHz-spaced frequency. Your narrowband consultant, dealer or equipment supplier can help determine if your equipment is capable of narrowband channel spacing and operation.
  • Many vendors’ narrowband equipment includes a “companding” or compression and expansion software feature (Motorola X-Pand and others). This software is designed to improve the quality of the received audio in narrowband operation. If companding is desired, make sure all radios in your fleet are companding-capable. If companded and non-companded radios are mixed, recovered audio will be distorted and unacceptable. If you use multiple vendors and wish to use companding, make sure the companding algorithms are compatible between vendor equipment. Test before you buy.
  • Financial considerations
  • Reach out to local, state and federal legislators to explore budget allocations for equipment updates or replacements. Because 2012 is the latest implementation year, allocations must be budgeted in 2011 or earlier. Grant funding is currently not available for this mandate.
  • Determine costs for upgrade, reprogramming or replacements.
  • Logistical implementation
  • Determine the logistics for touching every radio and how many touches are required.
  • Determine the timing.
  • Establish how the transition from wideband to narrowband will take place.
  • Verify how the quality of service will be maintained.
  • Identify interoperability considerations with mutual aid partners and local jurisdiction departments.
  • Evaluate the possibility of using this opportunity to implement improvements that had been postponed.
  • Review your FCC license(s) to ensure that you are authorized to use the narrowband emissions.
  • VHF interoperability channels

If you are licensed for channels on or adjacent to any of the new VHF interoperability frequencies, consider relocating to avoid interference to and from these frequencies.

Considering non-equipment

In addition to equipment, finance and logistic issues, organizations preparing for narrowbanding are taking a close look at several other factors.

  • System coverage

Contract with a qualified engineering and consulting firm to review coverage of your system at more narrow bandwidths compared to your current wideband system. Coverage may be reduced, especially at the edges, in current weak spots and in-building. Ensure that current tower sites will provide the needed coverage. If you employ a simulcast system, review the overlap coverage and system timing to ensure no new “holes” are created.

Paging and volunteer alerting must be considered. Pagers by nature often operate at the edge of coverage for the system, including in buildings, plants or mobile homes. Transmitter sites may need to be upgraded, relocated or added to maintain the desired coverage.

  • Paging

The Report and Order exempts paging-only channels from the narrowbanding requirement. These frequencies are designated as paging-only frequencies by Part 90.

If you provide alerting or paging on any other frequencies, your paging frequency must be narrowbanded.

Per 90.20(C), Limitations 13 & 30, the public safety pool paging-only frequencies are:

  • VHF — 152.0075 and 157.450MHz
  • UHF — None

Per 90.35(B)(3), Limitations 29 and 36, the industrial/business pool paging-only frequencies are:

  • VHF (in MHz) — 152.480, 157.740 and 158.460
  • UHF (in MHz) — 462.750, 462.775, 462.800, 462.825, 462.850, 462.875 462.900, 462.925, and 465.000
  • First responder paging and alerting

Fire/EMS/EMA alerting and paging is normally on dispatch channels, which must be narrowbanded. Plan to replace wideband monitor receivers, siren, house alerting receivers and monitor pagers, with current narrowband-capable equipment. Digital paging systems for station alerting and siren activation can also be considered.

  • Eliminating interference

Narrowbanding creates more frequencies at UHF and VHF. In the VHF bands, the narrower bandwidth will tend to reduce adjacent channel interference. However, in the UHF bands, the new 12.5 kHz channel spacing has potential to increase adjacent channel interference as additional 12.5 kHz systems are licensed in between existing 25 kHz systems.

Due to the widening receiver bandwidth of the 25 kHz systems, there will be interference generated to the 25 kHz systems by the 12.5 kHz systems. Likewise, the wider modulation emission mask of the 25 kHz system, typically 16 to 20 kHz wide, will “slop over” into the 12.5 channel. This situation will only be resolved by the current 25 kHz licensees migrating to narrowband 12.5 kHz emission mode.

Coordinating services with adjacent channel licensees will help minimize interference.

  • Migration to 6.25 kHz

In 2007, the FCC mandated that, by January 1, 2011, any equipment submitted for certification and sale must incorporate 6.25 kHz technology. This will set the stage for future FCC plans to split the 12.5 kHz bandwidth channels again to a bandwidth of 6.25 kHz per talk path, and list those channels in the Part 90 rules. Organizations planning a complete system replacement should consider migrating directly to technologies that meet the 6.25 kHz requirement. Equipment that meets the letter and intent of the FCC recommendations to bypass 12.5 kHz rebanding and move directly to 6.25 kHz equivalent will soon be available.

  • Public safety applications available

Current Project 25 (P25) radio systems meet the functional and operational requirements of the public safety community. The P25 Phase 1 technology is narrowband compliant, utilizing a 9,600 bps data stream in a 12.5 kHz bandwidth channel.

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.