Part 15: Let's talk about spectrum

I am reading several threads on the thought of expanding Part 15 or very low power broadcasting either as a service authorized by rule (unlicensed) or authorized by license.  I have seen several ideas come up as far as spectrum is concerned. I have seen mentions of longwave, 510 kHz, 520 kHz, 1710 kHz, 1710 to 1780 kHz and shortwave. 

First of all, let’s quickly talk about how spectrum is allocated. 

On an international level, spectrum allocations are maintained by the International Telecommunications Union, an international organization recognized by the United Nations.  Every few years, the ITU has a worldwide radio conference (WRC).  Every administration (such as the FCC, Industry Canada and the UK’s Ofcom) submits proposals for reallocations.  Most of the activity for WRCs involve microwave spectrum for satellite communications but at times, high frequency allocations are discussed.  There are times also that conventions will be held for a specific region.   The world is divided into three regions: Region 1 includes mainly Europe, Africa and the Middle East, Region 2 includes the western hemisphere (including the USA) and Region 3 includes Asia and Australasia.  

The 1988 ITU convention in Rio de Janeiro was the one that established the plan for the broadcasting service in the band 1605 to 1705 kHz.  The use of 1605-1705 for broadcasting is exclusive to ITU region 2 and is not available in parts of the world.   In other parts of the world, 1605-1705 kHz is allocated to fixed, mobile, maritime mobile, radiolocation (RADAR) and radionavigation services.  Even in Region 2, Fixed and mobile services retain a co-primary allotment in Region 2 and radiolocation is secondary. 

Now, within the United States, there are two federal agencies that manage radio spectrum.  The one you are familiar with, the Federal Communications Commission manages spectrum for all users except the federal government.  The Federal government’s spectrum needs are managed by the National Telecommunications and Information Administration (NTIA).  While the FCC is an independent agency, the NTIA is under the Department of Commerce.  Federal government spectrum use is therefore not licensed by the FCC and information on federal government use does not exist in the FCC’s Universal Licensing System (ULS) database.

In addition to the international table of allocations, each administration has their own table of allocations that states how that nation will use the spectrum within their nation in a manner consistent with the international table of allocations.   Within the United States, this table is further subdivided to government (NTIA) and non-government (FCC) uses.

Now, let’s look at the various bits of spectrum that people are talking about here.


For the purposes of our discussion, we will consider “longwave” as 148.5 to 283.5 kHz, which is the international allocation for longwave broadcasting in ITU Region 1.  Longwave broadcasting only exists in Region 1 and even with that, the spectrum 255-283.5 kHz is co-primary with aeronautical radionavigation.  Many African nations also use 200-250 kHz for aeronautical radionavigation.

Let’s look at this spectrum in Region 2 and in the United States:

148.5-160.0 kHz is internationally allocated to the fixed and maritime mobile services.  This spectrum is still on the books from the Morse days and its use is outlined in §80.355(a) of the FCC rules.  The international calling frequency for ships desiring to communicate with a coast station is 143 kHz.  While Morse is not regularly used in the maritime services anymore, this allocation is still on the books. 

160-190 kHz is allocated internationally to the fixed services.  This spectrum is already available for Part 15 usage as defined in §15.217 of the rules.  The “Lowfer” band can be used by anyone with up to 1 watt input to the transmitter’s final stage and the entire transmission line can not exceed 15 meters.  According to the ARRL, there are CW (Morse code) beacons in the 170-180 kHz portion of the band.  

190-283.5 kHz is allocated to aeronautical radionavigation for radiobeacons.  This assignment can be found in §87.475.  There are also secondary allocations to aeronautical mobile and maritime the radionagivation services.

The Amateur Radio Service has tried in the past to obtain an allocation at 160-190 and like with the allocation they are seeking in the 135.7-137.8 kHz band, there has been substantial push back from the electrical utility industry.  This is because these low frequencies are used as part of a power line carrier (PLC) system which sends data communications for maintenance of the system over the power lines.  This is not to be confused with broadband over power lines (BPL) which was an offering of direct to home broadband services and utilized high frequency spectrum (3-30 MHz) over the power lines.

If someone wishes to place a broadcasting device in the 160-190 kHz spectrum, I do not see a legal issue with that as long as the provisions of §15.217 are met.  Please keep in mind though that there is an existing Lowfer community that uses that spectrum for non-broadcast weak-signal use.

Medium Wave

There has also been some discussion of starting a license free service that is based around 510 and 520 kHz as well as allowing the use of 1710 kHz for license free use.  There is also suggestions of a potential licensed LPAM service in 1720 to 1780 kHz. 

First of all, we will talking about licensing vs. authorization by rule in a future discussion.

Let’s look at the spectrum below 540 kHz.  505-510 kHz is allocated internationally to the maritime mobile service and 510-525 kHz is allocated to both maritime mobile and aeronautical radionavigation.  For aeronautical, this spectrum is used for radiobeacons (§87.475(b)(2)).  The Maritime service designates 512 kHz as a working frequency for ships while 518 kHz is used by the Coast Guard to send meteorological and navigation warnings to ships using narrowband direct printing.  There are also navigation aids in the spectrum 510-535 kHz which are under the jurisdiction of the NTIA. 

This means that 510 and 520 are already spoken for.  I do not see these as good Part 15 or low power AM channels due to the overall requirements to build an efficient antenna at this wavelength.  The lower AM frequencies are also more vulnerable to local electrical noise. 

One thing to take notice of is that §15.219 of the rules (the 100 milliwatt 3 meter antenna rule) would allow operation at 520 kHz but will not allow operation at 510 kHz.  This is because the rule manages operation from 510-1705 kHz and a carrier on 510 kHz would go out of band.

Now, let’s go above the band and look at the world above 1700 kHz.

I know there are many Part 15s that operate on 1710 kHz.  First of all, 1710 kHz is not covered under §15.219 of the rules.  It is covered by §15.223 of the rules which is based on field strength and not on power level.  Therefore, your Rangemasters and other AM transmitters at 1710 kHz may not be legal.

If we look at this spectrum in the United States, we will find that it is allocated to both government (NTIA) and non-government (FCC) users for the fixed, mobile and radiolocation services.  1709 and 1712 kHz are also allocated to the Alaska Fixed Service (§80.387(b)).   Also, some frequencies in this spectrum are still on the books for Part 90 land mobile services including 1722 and 1730 kHz which are in the public safety pool. 

In other words, to clear or otherwise use the 1705-1800 kHz, it is going to take coordination with NTIA to assure that federal government users are not impacted. 


There has been talk about broadcasting in the shortwave bands, which we should refer more as just high frequency (HF).   The shortwave bands are just specific bands of frequencies within HF similar to the bands reserved for Amateur use.  Frequencies for use by broadcast stations in the shortwave bands are handled through the High Frequency Coordination Committee (HFCC).  Twice a year, the HFCC has a conference to work on the schedule for the next 6-month season (summer and winter). 

Allowing for broadcasting, especially in the lower bands (such as 49 and 41 meters) would be a very touchy subject and would likely be frowned upon, especially in light of the ongoing HF pirate activity, especially around 40/41 meters.

There are a couple of places that one can look for low power experimentation in the HF bands.

The spectrum 13.553-13.567 allows for operation not exceeding 15,848 microvolts per meter at 30 meters.  There are some additional restrictions that can be found at §15.225.

Another piece of spectrum to consider is 26.96 to 27.28 MHz.  Yes, that is the spectrum around the 23 original CB channels.  While operation at 5 watts is allowed by rule under Part 95 of the rules, there are rules in Part 95 that prohibit one-way communications §95.413(a)(4) and music and other entertainment §95.413(a)(6).   You may use this spectrum with a maximum of 10,000 microvolts at 3 meters per §15.227.  This was to accommodate the old toy walkie-talkies and other license-free devices that took advantage of the CB spectrum. 

Just slightly down the dial from CB is the 11 meter shortwave band which runs from 25,600-26,100 kHz and there is an adjacent band used under Part 74 for broadcast auxiliary from 26,100-26,480 kHz.   Broadcast auxiliary can also use a portion of the 11m shortwave band on a secondary basis.  In the past, REC has recommended this spectrum for low power (analog) community broadcasting.  This spectrum can also be a good migration point for Class C and D AM stations as a part of AM revitalization.   Over the past few years, some nations have started to use the 11m band for local broadcasting using the Digital Radio Mondiale system. 

So as we look at these bands, we still have to keep in mind that while these frequencies may seem “quiet” where you are at, these frequencies are already allocated to other services and any evaluation to expand licensed or unlicensed services will need to look at the potential for interference to the incumbent services including those federal government services that are not as well publicized like the FCC managed services.  For those who are familiar with the 60 meter amateur radio band, the spot frequencies were designated in cooperation with the NTIA.  The change of one of the spot frequencies (channel 3 on many older radios) was as a result of a request by NTIA. 

Any petition that goes to the FCC should go in with substantial technological backing.  Keep in mind, there will be many different interests, well beyond the NAB, that will oppose any new “visitors” into their spectrum, even if they hardly use it. 

REC supports a slightly improved power level and antenna restriction for intentional radiators in the 1615-1705 kHz band.  The United States is only one of a few countries that even has a license free very low power service in the AM broadcast band.  Even the carrier current AM stations in the UK require a license.  There is no provision for AM low power devices in any of the CEPT (Europe) countries and most other countries just simply do not include AM.  Perhaps it was because Mr. Microphone was just an American thing.