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New Zealand Has Legal Unlicensed Low-Power FM

I was in New Zealand over the recent holidays, and while waiting in line at a beachside food stand near Christchurch I noticed a t-shirt the teenager behind the counter was wearing, advertising “Rotten Radio 107.7 fm, Lyttelton.” I asked him about the station, and he only said that it’s “cool” and I should listen to it. After getting my fish and chips I quickly looked it up on my phone and only found a Facebook page, with one post noting that the station is raising funds to broadcast online.

After a little more digging I figured out that Rotten Radio is a low-power station, using a class of service that doesn’t require a license in New Zealand under the Ministry of Business, Innovation and Employment’s General User Radio License. Since 1993 unlicensed low-power stations have been permitted on the so-called “guard bands” of the FM dial, from 86.7 to 88.3 mHz on the left end and from 106.7 to 107.7 MHz on the right end. Broadcasters may use up to 1 watt of power; prior to 2010 the limit was a half-watt.

Minimal Requirements for NZ LPFM

Low-power broadcasters are not required to register, and the government does not coordinate stations in any way. Broadcasters’ obligations are to avoid interfering with any licensed station, and to broadcast contact information every hour. Additionally, a broadcaster may not broadcast another station with “substantially the same programme (including simulcast or re-transmission)” within a 25km radius of the first station.

While unlicensed broadcasters may use up to 1 watt of power, there are also limits on the signal strength as received 100 meters from the transmitter (95 dBu V/m). This is similar to the limit on unlicensed Part 15 FM broadcasting in the US, except New Zealand’s limit is much higher. The apparent purpose of this signal strength requirement is to limit how much antenna design and placement savvy can be used to maximize the broadcast radius.

Furthermore, broadcasters are expected to control “unwanted emissions,” which are transmissions on frequencies other than the main broadcast. All transmitters generate these “spurs” to some extent but well designed transmission systems filter them out. Those who want to dig into the technical details can read the Ministry’s full regulatory notice on low-power FM.

Along with the fact that unlicensed broadcasters are completely uncoordinated, it’s interesting to me that broadcasters may use any transmitter or antenna they can obtain, so long as their transmission obeys the rules. I might have thought that only approved devices would be permitted, kind of like unlicensed Citizen’s Band radio in the US. However, I suspect such approvals would be impractical in a country the size of New Zealand (population: 4.4 million), where the demand for such broadcasting equipment would be tiny.

One concern that immediately springs to mind is that the reserved LPFM “guard bands” could quickly turn into a mash of chaotic interference, with uncoordinated and irresponsible broadcasters going on air without regard to other stations. However, that doesn’t appear to be the case. That may be due to the still very low power limits, the expense of building and running a station, the polite nature of Kiwi culture, or some combination of these factors.

The LPFM Society of New Zealand exists to advocate for and assist unlicensed broadcasters. Its work includes maintaining a registry of stations and helping to resolve interference issues and disputes. Only two “historical complaints” of interference are recorded on the society’s website, one from 2010 and another from 2011.

During my stay in Christchurch in the inner suburb of Linwood, about 2km from the central business district, I was unable to tune in any actual LPFMs. Now, I only had a pocket travel radio and a small stereo in the house at my disposal, which would have made it difficult to hear any station not within about a 10 block radius or so. A car radio would have been ideal, but I didn’t have one. So, that meant I couldn’t tune in the station that inspired my investigation, Rotten Radio, since it’s located 11km away in Lyttelton.

Many New Zealand LPFMs maintain a web presence and internet stream, so at least we can tune in virtually. A Wikia page keeps a list of stations, though due to the entirely unregulated nature of the service, any such list is provisional at best. (For instance, Rotten Radio is not listed.)

Could It Work in the States?

Learning about NZ LPFM certainly got me wondering if such a service could work in the United States. No doubt, even with licensed LPFM, there’s demand for a more robust unlicensed service. That would open up opportunities for “pop-up” stations broadcasting in coordination with community events, part-time stations or allow schools or other non-profits to start broadcasting with the kind of low commitment and cost associated with internet broadcasting.

A higher powered unlicensed service could be particularly helpful in places with a a high density of pirate stations, like Brooklyn, Boston and South Florida. However, it also stands to question if broadcasters like these would adhere to technical limits, or cooperate and share frequencies.

Setting aside a set of frequencies as in New Zealand is certainly the most efficient way to create an unlicensed service while minimizing interference with licensed stations. That would be difficult in the US, where the FM dial in most urban areas is already mostly spoken for.

However, there is a little slice of spectrum down at the far left end that is not currently licensed, 87.7 and 87.9 FM. The lower of these frequencies–87.5–is not officially part of the band, but most radios are able to receive it. Historically neither of these frequencies were allocated because of their proximity to TV channel 6. But this conflict mostly went away with the digital TV transition in 2009. There are still a handful of low-power analog channel 6 TV stations around, some of which effectively act like radio stations because their audio can be picked up around 87.5.

It’s plausible that the FCC could open up 87.7 and 87.9 FM for New Zealand style unlicensed broadcasting in areas where there are no low-power TV stations on channel 6. When the Commission finally sunsets analog LPTV, then these frequencies could be available everywhere.

With a limit of just one watt of power, quite a few stations could share even just two frequencies in most towns just by putting enough physical space between them. Yet, it’s still possible that demand could outstrip supply in very dense cities like New York.

I doubt this is something that the National Association of Broadcasters would go for, even if offered as a way to entice current pirate broadcasters away from licensed stations on the rest of the dial. Because of that, it’s unlikely the FCC would be inclined to implement such a service, either.

Nevertheless, one can still dream.


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