FCC Continues Path to Eventual 6.25 kHz Narrowbanding
By Greg Kunkle
Tuesday, August 01, 2017 | Comments
One question clients frequently ask me is “When is the FCC going to require VHF and UHF land mobile users to transition to 6.25-kilohertz technology?” When and how the transition to 6.25 kilohertz will happen is anyone’s guess. But the FCC does continue to remind licensees that the transition is still in the commission’s future plans. The most recent example came just a few weeks ago in the FCC’s June 30 order denying a request for waiver filed by the International Municipal Signal Association (IMSA). IMSA had sought a waiver of the FCC’s prohibition against certification of VHF and UHF (150.80 – 162.0125, 173.20 – 173.40 and 421 – 512 MHz) LMR equipment that is not capable of operating on 6.25-kilohertz channels or with equivalent efficiency. IMSA requested the certification requirement deadline be extended until at least January 2020.

This began more than 20 years ago in 1995, when the commission announced that as of Jan. 1, 2005, it would no longer certify equipment that could not operate on 6.25-kilohertz channels or with equivalent efficiency. This deadline was later pushed back several times until it finally took effect Jan. 1, 2015. The prohibition does not actually require users to operate in 6.25-kilohertz mode. Also, equipment certified prior to the deadline may still be sold, whether or not the device has 6.25-kilohertz capability. But any manufacturer seeking to obtain certification for new equipment or making changes to an existing model that requires recertification must include the capability to operate in 6.25-kilohertz mode or equivalent efficiency.

In its waiver request, IMSA argued that the commission’s certification deadline effectively required new radios to be digital because analog technology generally does not meet the 6.25-kilohertz requirement. IMSA claimed that the “6.25-kilohertz channelization requirement prevents manufacturers from improving current products” unless they also include 6.25-kilohertz capability, which customers may not want or even be able to use to the extent their current deployment is analog. IMSA stated inclusion of a 6.25-kilohertz capability would “inevitably” raise radio prices. Because customers may not be willing or able to afford the additional expense, manufacturers potentially would forgo adding new features to existing radio products that could enhance public-safety capabilities.

IMSA believed this to be an undue burden on public-safety users. The hardest hit users likely would not be large urban agencies, which may have already transitioned or are planning to transition to digital networks, but would almost certainly be smaller volunteer fire departments and other similar public-safety providers that often are forced to make the most of very limited budgets, IMSA said.

IMSA also noted that, unlike the developed standard for Phase 2 Project 25 (P25) trunked operations, the standard-setting process for Phase 2 P25 conventional 6.25-kilohertz operations has not yet been completed. IMSA questioned the wisdom of requiring manufacturers to implement a 6.25-kilohertz capability that may be incompatible with any future standard and noted the commission itself had previously remarked that, “proliferation of 6.25-kilohertz equipment that is incompatible with the P25 Phase 2 standard could undermine interoperability.”

IMSA pointed out that the commission recently eliminated the 6.25-kilohertz capability requirement for 700 MHz band public-safety equipment. If the requirement no longer made sense at 700 MHz, why continue to apply it to the bands below 512 MHz?

On June 30, the commission ultimately rejected IMSA’s arguments and issued an order denying its request for waiver, choosing instead to leave the Jan. 1, 2015, deadline in place.

Interestingly, the commission did not directly rebut IMSA’s assertion that a mandated 6.25-kilohertz capability would increase equipment costs for public-safety users. Instead, it said commenters in the proceeding had presented “conflicting assertions” regarding costs and there was no “clear evidence” to support IMSA’s position. The commission stated that some comments in the proceeding claimed market competition has kept the price of 6.25-kilohertz-capable equipment comparable to that of similar equipment without 6.25-kilohertz capability. The commission also questioned whether other cost estimates showing an increased burden on public safety were made on an apples-to-apples basis or were instead comparing low-end analog radio models to high-end expensive equipment. Although equipment costs would appear to be something that the commission could reasonably ascertain, the FCC typically does not perform that type of independent fact finding in response to waiver requests. Here, the commission found IMSA had not demonstrated that continued implementation of the 6.25-kilohertz capability requirement would be inequitable and unduly burdensome.

The FCC also rejected any similarities between the elimination of the 6.25-kilohertz requirement at 700 MHz and the continued implementation of the requirement for the bands below 512 MHz. In addition, the commission summarily dismissed the notion that an ongoing P25 standards process should alter continued implementation of the 6.25-kilohertz certification requirement.

Many will be disappointed by the decision.

Of possibly wider interest, the commission took the opportunity to again reiterate that it intends a further migration from 12.5- to 6.25-kilohertz licensing at some point in the future. Its order characterized the current 12.5-kilohertz landscape as a “transitional step in the eventual migration to 6.25-kilohertz technology” and stated that it would mandate such migration, as opposed to allowing for a voluntary transition, if necessary. Central to the FCC’s decision was the fact that removing the 6.25-kilohertz capability certification rule would increase the embedded base of equipment that is 12.5-kilohertz capable only. Such equipment would need to be replaced once the 6.25-kilohertz transition occurs.

One question the FCC did not answer is when the transition to 6.25 kilohertz will occur. Logically, if the transition is soon, it does not make sense to allow manufacturers to continue to certify new equipment that will need to be replaced within its expected lifetime. This is likely worse for cash-strapped agencies than the incremental cost of requiring 12.5-kilohertz radios to include 6.25-kilohertz capability now. However, IMSA’s request to extend the certification requirement starts to make more sense if the timeline for the 6.25-kilohertz migration is far enough away.

How long that timeline is remains to be seen.

Greg Kunkle is a partner in the law firm of Keller and Heckman, practicing in telecommunications with an emphasis on assisting corporate clients and trade associations with legal and regulatory matters before the FCC. He is president of the Land Mobile Communications Council (LMCC) and a member of the Federal Communications Bar Association.

Post a comment
Name: *
Email: *
Title: *
Comment: *

On 8/14/17, Leon van der Linde said:
On the one side I can see IMSA's complaint.
Digital Mobile Radio (DMR) and Project 25 (P25) Phase 2 is 12.5 kilohertz and will never be 6.25 kilohertz. Unless the FCC bans DMR they will never be able to implement 6.25 kilohertz. Virtual 6.25 kilohertz is NOT 6 25 kilohertz. This is something the FCC needs to explain as this will impact worldwide communications as the world looks at the USA as a leader in communicatons.
I do think the FCC is correct in forcing 6 25-kilohertz capability. Here I do agree 100 percent.

On 8/9/17, Peter Moncure said:
The premise is simple — add interstitial splinter channels between those in use, allow only narrower modulation on those, time limit the wider modulation and you will eventually have two times the spectrum.
There are two major flaws in the implementation however.
The time limiting, which is the subject of your excellent commentary, unfortunately allows for channel equivalency. In other words, you can keep using wide modulation types as long as you have two voice or data paths. Since a wide channel blocks both adjacents, this results in a much smaller efficiency — say 1.4 times depending on how you measure it versus time.
Recommendation: Also phase out all wide modulation types. At VHF it is even worse because the FCC allows 12.5-kilohertz modulation types on 7.5-kilohertz channel bandwidths, which is mathematically unsupportable and practically interference-prone especially with the above-mentioned TDMA wide modulation types. This is heavily exacerbated by the mixed use of most VHF channels as base OR mobile so one man's TDMA base station may be another's 7.5-kilohertz adjacent mobile receive channel. The only solution to this in addition to phasing out wide modulation types as above is to replan the VHF Part 90 spectrum, which is so expensive as to be politically painful.
Recommendation: Require new applicants to conform to a segregated base and mobile channel plan and take the 10-year renewal cycle as a slow enough approach to make it possible. This of course will be impossible unless all users are migrated to true 6.25 kilohertz, not equivalent technology as well. This would yield true two times efficiency for desperately needed VHF spectrum in 10 years plus FCC decision and implementation time. I won't hold my breath.

On 8/4/17, Richard I Terwilliger said:
The 6.25-kilohertz mandate is ridiculous. We had prepared for 12.5 kilohertz and handled the migration with no problems. Meanwhile public-safety users using 470 – 512 MHz have to vacate. Also the extra frequencies made available by the 12.5-kilohertz mandate have not been farmed and utilized.

On 8/2/17, Stan Reubenstein said:
Unless agencies insist on buying pricey Project 25 (P25) Phase 2 radios from Motorola and other higher priced brands, there are other venders that can supply compatible and equivalent radios for much less. While I am not a fan of Digital Mobile Radio (DMR), one of the equivalent efficiency modes is readily available from many vendors for bargain prices. NXDN available from JVCKENWOOD, Icom America and others is a popular discrete mode that is less expensive and feature rich with affordable infrastructure.

On 8/2/17, Gerald Marsh said:
I have used P25 Phase 1 and 2, NXDN and MOTOTRBO, all in hilly terrain and city areas and found that all have poor audio at times due to multipath. In the flat lands all seem to work just fine but with less range than with analog radios, which have better audio quality. My fire department is using $7,500 apiece mobiles and portables and my $600 analog radio sounds much better and works better on the VHF frequencies because the portable radio antenna is not a compromise for the more expensive tri-band portable. The digital systems have required much more infrastructure to cover areas that the old VHF analog system was covering. Agencies with budget problems just cannot afford the expensive radios and the facilities to support the systems. The adjacent counties to mine have to rely on patching systems to communicate with us for mutual-aid responses as they cannot and will not purchase the expensive tri-band digital equipment. Their analog sounds so much better. We volunteer firemen have lost the ability to hear any communications after the initial dispatch on the VHF analog channel as all communications are on 700 MHz P25 Phase 2, and the department will not provide us radios with high cost. We have to depend on unreliable smartphone applications that scan all channels instead of our working talkgroup. I see it as a step backwards instead of improvements for voice communications. With proper simulcast VHF analog systems, large areas are covered for a significantly lower cost.

On 8/2/17, Jim Shannon said:
To comment on Mr. Stan's remarks, Digital Mobile Radio (DMR) is very desirable in that it offers two talk paths under one frequency rather than only one with NXDN.


May 2023

23 - 25
Critical Communications World (CCW)
Helsinki, Finland

More Events >
White Papers
More White Papers >

Site Navigation