(T7B09) Part 15 Devices

T7B09  from the Technician License Course Section 12.0, Avoiding Interference:

What is a Part 15 device?

A. An unlicensed device that may emit low powered radio signals on frequencies used by a licensed service
B. A type of amateur radio that can legally be used in the citizen’s band
C. A device for long distance communications using special codes sanctioned by the International Amateur Radio Union
D. A type of test set used to determine whether a transmitter is in compliance with FCC regulation 91.15

Part 15 of Title 47 of the Code of Federal Regulations regulates low power, unlicensed devices that can cause interference on the ham bands. So, that pretty much points to the correct response here, but let’s dig a little deeper.

You probably have several Part 15 devices in your home or office. Example include baby monitors, radio controlled toys, wireless thermometer sensors, wireless computer peripheral devices, and about a gazillion other things these days. Just look closely at the information tag on a device and you’ll be able to see if it is an emitter of RF under Part 15 provisions, and usually be able to see the frequencies emitted. Part 15 devices share frequencies with those allocated to other licensed radio services, including our Amateur Radio Service!

In theory, those Part 15 devices output such low powered signals that they will not interfere with the licensed radio services using the same frequencies.  Nice in theory, but as Yogi Berra told us:

In theory, there is no difference between theory and practice. In practice there is.


Courtesy BoingBoing.net

While most folks will never notice the small transmissions of these devices, they CAN interfere with some ham radio operations due to the highly sensitive radio gear we use. A television or stereo is not apt to be disrupted by these weak signals, but they can be much stronger than those the ham typically seeks to receive from the other side of the planet, or even those from a distant repeater.

So, what if you ascertain that a Part 15 device is causing you receptive grief? If it is yours, turn it off, or better yet, use a hammer on it. Several blows, just to be sure. If it is a neighbor’s device and it is causing harmful interference, the operator of the Part 15 device (your neighbor) is responsible for ending the interference, usually by not using the device any more. Good will and a friendly disposition can go a long way when informing neighbors they are violating FCC rules and have to stop. Good luck.

Just for good measure, harmful interference is defined as:

Any emission, radiation or induction that endangers the functioning of a radio navigation service or of other safety services or seriously degrades, obstructs or repeatedly interrupts a radiocommunications service operating in accordance with (the rules).

The answer to Technician Class question T7B09, What is a Part 15 device?”is “A. An unlicensed device that may emit low powered radio signals on frequencies used by a licensed service

Related Questions:  T7B08, T8C01