VHF-UHF Narrowbanding

UPDATE February 2015:

Licensees who modified their existing analog systems to comply with the FCC narrowbanding mandate may
now find that their coverage has deteriorated due to the reduction in system performance which results from
the reduction of system deviation.

Leikhim and Associates can provide a system analysis to determine what modifications can be done to restore
the coverage of your system to meet expecatations. For example, you may be able to improve portable
coverage of your analog system through the addition of satellite receiver sites or through a space diversity
technique using your existing tower. In some cases a digital system upgrade, including replacement of all
subscriber equipment may be the best option. 

To help you make a decision, please contact us for a telephone free consultation.

UPDATE January 2014:

Although the FCC deadline for narrowbanding has passed, many system operators have requested waivers
and are relying on the FCC to permit them additional time to resolve unexpected problems. Other licensees
may have performed work to meet the deadline yet have additional requirements which need to be met with
respect to system performance or other licensing issues.

Leikhim and Associates can help licensees meet FCC compliance and perform "due diligence" to ensure
that work performed by others meets the FCC requirements and provides performance required for their

In a rulemaking with its origin dating back to 1995, the FCC mandated a process called "Refarming" which is
intended to increase the number of assignable channels within the VHF 150-174 MHz and the UHF
421-512 MHz bands. As a result, the FCC has ruled that  licensees of Part 90 radio systems within those
bands are subject to the following FCC mandates:

On or before January 1, 2011:

No applications for new systems or modification applications that expand the authorized contour of an
existing system operating at greater than 12.5 kHz equivalent spectrum efficiency will be accepted.

On or before January 1, 2013:

Radio systems must operate in 12.5 kHz equivalent spectrum efficiency or better.

Mobile data systems will require data efficiency of 4800 bps for a 6.25 kHz channel, or 9600 bps for a
12.5 kHz narrowband channel.

On January 1, 2013, licensees must have ceased wideband operation of their systems and must convert
licenses to narrowband emission designators. You may remain on the same channel center as before.

Licenses, which have not been modified for narrowband will be cancelled by the FCC and the
licensee will be in violation, will need to cease operations or be subject to fine or other
enforcement action. Licensees, who convert licenses to narrowband but fail to make
appropriate changes to their systems, will be in violation and subject to fine or other
enforcement action.

Narrow Band Transitioning Services

Leikhim and Associates can assist you by performing an assessment of your existing equipment inventory
and will recommend compatible replacement equipment. Leikhim and Associates can also assist in the
modification of the system to narrowband operation and the required modification of your licenses.

System Compliance Audit

If you believe your agency has complied with narrowbanding requirements but wish to perform due
diligence to ensure that the equipment complies with the FCC mandate and is performing properly,
Leikhim and Associates can provide an audit of the system subscriber and fixed equipment.

Potential Financial Impact of Narrowbanding:

Subscriber and Fixed Equipment Replacement

Handheld radio equipment already in service by your agency may already be capable of 12.5 KHz
narrowband operation since the FCC required that new equipment type accepted after
February 14, 1997 include the 12.5 KHz bandwidth capability. Because manufacturers could continue to
sell older model radios for a time, there are exceptions in that some VHF radio equipment may not properly
resolve certain channels, which require the radio to resolve to 2.5 KHz channel steps.

Examples are

VCALL -10 155.7525 MHz,
VTAC - 12  154.4525 MHz and
VTAC - 14  159.4725 MHz

These channels cannot be evenly divided by radio synthesizers, which do not resolve to 2.5 KHz
Additionally, there are other VHF channels on these "7.5 KHz channel centers" which may be

As noted above, manufacturers continued to market certain popular model radios well after Feb. 1997
so the possibility exists that incompatible equipment remains installed in vehicles or has been handed down
to lower priority services.  

Fixed equipment such as base stations, control stations and repeaters are often overlooked in system
upgrades and continue to be operated for decades as primary or back up equipment. It is common to find
a non-compliant MSF-5000, MSR-2000, MASTR-II or even a 30-year-old MICOR station still in service.

Impact on Radio System Performance:

Making the transition to narrowband may have impact on your existing system’s ability to meet expected
coverage performance.

The table below describes the performance impact when transitioning from 25 KHz wideband to 12.5 KHz
narrowband channels.  Using analog wideband as a reference, for an analog system there will be 3 dB
performance degradation. This will result in reduced delivered audio quality (DAQ) and/or reduced coverage

Note that transitioning to narrowband APCO Project 25 narrowband digital technology will yield approximately
6 dB improvement in coverage. However this is a costly conversion alternative for many agencies.



25 KHz Analog (Wideband)

12.5 KHz Analog (Narrowband)


12.5 KHz P25
C4FM/CQPSK (Narrrowband)


Transmitter Deviation +/-






Receiver Effective Noise Bandwidth






Receiver Sensitivity 12 dB SINAD (Example: Motorola Quantar 0.35 uv / -116 dBm)






12 dB SINAD Static CPC






"Inferred Noise Floor of RX"












Faded Sensitivity of Receiver






Performance Impact relative to WB Analog (minus is degraded)










Ref: TSB-88B Table 1-A, Table 2







The following figures compare the relative coverage of a UHF system under the conditions of Analog Wideband,
Analog Narrowband and Digital (P25) Narrowband:


Analog Wideband 25 KHz UHF Coverage Example (above)




Analog Narrowband 12.5 KHz UHF Coverage Example (above)




Digital P25 Narrowband 12.5 KHz Coverage Example (above)

Impact on Interoperability:

The ability for your agency to interoperate with outside agencies or even between departments internal to
your agency will be affected during the transition to narrowband operation. Factors including the timing of
cutover and technology changes such as analog to digital will be important considerations.

Leikhim and Associates can assist you in determining the best course of action.

Narrowbanding Services:

To assist you in making the best plan to meet this mandate, Leikhim and Associates can provide a technical
analysis of your existing system to determine the impact if any, of the transition to narrow band. As part of this
analysis, Leikhim and Associates will provide recommendations for improvements to be made to minimize the
coverage impact or improve performance as a whole.