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Written by Tony Stillman
Flying Site Assistance
Column
As seen in the April 2017 issue of
Model Aviation.


Hello again! By the time you read this, things should be starting to warm up here—with expectations of getting my new F8F Bearcat in the air!

I had an online conversation with an AMA member who wanted AMA to explain how the Federal Communications Commission (FCC) is involved with RC model aircraft. Actually, there are several areas of our RC modeling that the FCC monitors and regulates.


Radio Frequencies

The area that most are familiar with is the frequencies that our RC systems use. AMA has been involved with the FCC and our need for frequencies for many, many years! Just a few years ago, RC was flown on frequencies other than the current 2.4 GHz spread spectrum systems.

In the early days of RC, you could only fly on 50-53 MHz Amateur Band equipment, which required an FCC Technician Class license to operate. Later on, Citizen’s Band radio was created and we were able to use 27 MHz frequencies as well. In the late 1960s, we added 72 MHz for aircraft only and 75 MHz for RC cars and boats. Specific frequencies within these bands were referred to as channels.

Modelers with an FCC Technician Class (or higher) license were the only ones able to use this specific frequency band (50 to 53 MHz) to remotely control a model. If two modelers tried to operate on the same frequency at the same time, interference would occur, with an inevitable crash to follow! Although these frequencies are still available today, 2.4 GHz spread spectrum has proven to be a more reliable way to fly without concerns of interference from other modelers.

There are other radio bands that amateur radio operators can use, depending on their level of licensing. Amateurs are allocated 26 bands (e.g., specific groups of frequencies) spaced from 1.8 MHz, which is just above the broadcast radio frequencies, all the way up to 275 GHz. Most of the frequencies are not for radio control of devices, but are used for communications.




This is a Spectrum Ultra Micro FPV Camera and Transmitter—no FCC license is required.



Special-Use Licenses

In the world of FPV model flying, the use of a video transmitter mounted on the model to transmit a video signal from the camera to a monitor or set of goggles can be done on several frequencies. However, the use of certain frequencies at certain power levels requires an FCC license.

Typical model use today would be in the areas of FPV drone or fixed-wing racing. A commonly used frequency is 5.8 GHz. In order for an unlicensed person to use this frequency band, the FCC only allows specific power output maximum levels.

In this case, they use a complex calculation based on the measured output of the device from a specific distance away. If the device falls below a certain threshold, the FCC requires an FCC identification number on the device itself. This marking indicates that the transmitter can be legally operated without a FCC license.

These items have been tested and determined to have low enough power levels, and a fixed antenna as part of their design, so that they will not be an interference threat to other users. Typically these will be 25 milliwatts (mW) of power or less, but the actual determination process is complicated.

However, if the item’s output power is above this level or the antenna is replaceable, there will not be an FCC identification number on the product, and it will require the proper FCC licensing to operate.

Part of the complexity is that the item can have its power output increased by the use of different antennas attached to it. Antenna designs can increase or decrease the measured output of a device, known as “gain.” This increase in power is measured in decibels or dB. Because of this, most radio frequency units used in today’s FPV aircraft for transmitting a video signal will require the operator to have an FCC Technicians Class license. This is because of its higher level of power output, and also because the design of the unit allows for a screw-on antenna that can be switched out for different designs that have more power or gain.

The FCC determined that, because users can influence the output of the device this way, they need to have some knowledge about what interference could be caused unintentionally to other users by making, among other things, an antenna change. Hence the need for the license.




ImmersionRC RaceBand 600mW, 5.8 GHz, 15-Channel A/V Transmitter—FCC License required.


So, what have we learned?

1) In order to operate an RC transmitter on 50 to 53 MHz, you must have an FCC Technicians Class license.

2) If you use a video transmitter on 5.8 GHz and operate an RC vehicle (such as FPV) you must verify that it has an FCC ID sticker on the video transmitter unit itself, or have an FCC Technicians Class license in order to operate it.

What do you do if you don’t have a license and want to get one? The American Radio Relay League (ARRL) conducts classes to prepare students for and to administer the tests for FCC licenses.

You can go to the organization’s website at www.arrl.org and click on “Get your license” to learn about costs and classes in your area. Classes are run by local chapters of the ARRL and are inexpensive. When I took my class, the cost was roughly $35, which included a textbook for study. If you are interested in FPV, this is a must-have to be legal.

I hope this helps you to better understand the requirements under US law to use these specific pieces of equipment.

-Tony Stillman
fsac@modelaircraft.org






9 comments

What have I missed that the seemingly innocuous question "Do you need an FCC license?" is the format by which the AMA is notifying flyers like myself that any video transmitter with an output greater than a pathetic 25 MhZ now requires an FCC license?

Is this another 'new' rule that was added on top of all the other rules we now suffer through thanks to the complete ineffectiveness of whatever 'lobbying' effort the AMA has put forth or is it something that I just missed?

When was this 'rule' added and what did the AMA to argue it?

What have I missed that the seemingly innocuous question "Do you need an FCC license?" is the format by which the AMA is notifying it's members of what seems like a new rule at least I (if no one else) missed? Seriously, any video Tx over a pathetic 25 Mhz requires a license now? What about transmitters at 2.4 or lower? Same output limitations?

Is this a new rule or one that just hasn't been discussed openly? If new, when was it implemented and what did the AMA do to argue the point and lobby on our behalf?

I have been a member for 35 years and cannot believe how ineffective the AMA has been in protecting the rights of its members. One failure after another from my perspective. Sorry to be blunt.

Several errors are contained in this article, in particular the frequencies allocated to Amateur operators:

Lowest frequency: 135.7 kHz
Highest frequency: NO upper limit, see for specifics:

http://www.arrl.org/files/file/Regulatory/Band%20Chart/Band%20Chart%208_...

As a Volunteer Examiner Coordinators authorized by the FCC to test for new licenses, the typical charge for testing is $15, with some lower, even free. Study can be accomplished within several websites, also free:

https://www.qrz.com/hamtest/

https://www.eham.net/exams/

I just want to add on to this article.

One thing I've noticed in the Multirotor FPV community is there is a pretty big divide between people who feel that needing to get a license is "encroaching government oversight" and the people who feel that it's not entirely unreasonable.

I went ahead and got my FCC license before I put my quad in the air. Aside from complying with the law, the things that you learn as a Tech level FCC ham operator really can help you troubleshoot your model. Weather it's a Quad, broadcasting FPV footage at 5.8Ghz, or even your TX/RX controls operating at 2.4Ghz, the knowledge is invaluable. I'd highly recommend it, a couple of weeks to a couple of months of study is all it takes, and it really does help!

The link in the email might be mis-interpreted that if you run low lower power, you don't need a license. This is addressed in the article but bottom line is that to operate license free the transmitter needs to be FCC certified which means it will not have a removable antenna. I think the removable antenna will be the tell-tale for most people.

I just wanted to add that the Tech class ham license can be done 100% free.

I studied using the free Android app "Ham Test Prep".

I looked for an exam locally and found a club charging the standard $15 exam fee. Later I found an organization offering the exams for free:

https://www.laurelvec.com

I think many people are intimidated by the exam. Just understand that the Tech license is the license to learn. It is made to be the entry level to Amateur Radio. You can do it!

S. Quinn - N7UAS

The FCC license requirement is not just for 50-53mhz and 5.8ghz. Above certain power levels a license is also required for the 900mhz frequencies and 2.4ghz frequencies.

Tony, I got my Technician’s license last year, and didn’t need to take the class. I was able to find sample tests online, flash cards, and basic info for free that did not require spending additional money.

Now, I will not say this is recommended for all; for me, it was a fairly easy test and did not require much in the way of study time, as I knew most of the basics. But, if you have no background in electronics, you might find it difficult.

Also, check your testing locations. Many receive grants to offer the test for free, so it doesn’t cost you anything. Most of the time, the test runs $15, and is good for a period of 10 years.

Very good article. Not mentioned is the video transmitters being sold are low quality regarding frequency tolerances and bandwidth. Having a armature radio license and saying you can use this equipment still may not be legal by F.C.C. rules. The idea of having the armature license assumes you can test the equipment to ensure it meets all F.C.C. requirements. Most licensed operators do not have the required testing equipment to ensure that they won't interfere with other legal communications equipment. I would like to see AMA getting involved in this area. We need video transmitter equipment that meets F.C.C. rules. The equipment price would increase some but the quality would be worth it. We could have more flyers flying at the same time on 5.8Ghz without so much interference from each other with better designed and manufactured equipment. It would be nice if a set of frequencies in the 5.9Ghz band be set aside for us and armature use. The equipment being sold for license free use would have to meet spurious frequency and bandwidth requirements. The manufacture would have his product(s) certified to meet the requirement, just has the way our 72Mhz and 2,4Ghz systems are.

This a good article. Taking it a step further I would like to say that having a ham license doesn't necessarily mean that the operator of a 5,8Ghz video transmitter is completely legal. The vast majority of the equipment does not meet proper bandwidth or spurious radiation requirements that keeps the equipment from interfering with other communications services. I would like to see AMA lead an effort to have the video transmitter manufactures meet strict requirements so there could be license free equipment made available to FPV flying. The manufacture would have certify their equipment to meet the requirements. This certification process is no different from the FCC certifications required for our 2.4Ghz or 72Mhz transmitters. Cost would increase but not that much to keep us from purchasing the equipment. By having good bandwidth requirements would allow multiple FPV flyers to fly at one time without the interference we are now experiencing.

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