In relation to my Part 97 post, I decided to do one on a portion of the FCC rules that most people have had at least some exposure to. If you look at almost any piece of consumer electronics that you own, you will likely find the following message:

This device complies with Part 15 of the FCC rules. Operation is subject to the following two conditions:
1. This device may not cause harmful interference.
2. This device must accept any interference received including interference that may cause undesired operation.

I have seen this on a variety of electronics from AM/FM radios, portable music players, and cordless phones to things such as my laptop computers. Undoubtedly, many of you have seen this message on devices you own as well.

Just what is it that this message is saying and why is it there and what is Part 15?

Part 15 is the portion of the FCC rules that regulates the unlicensed operation of radio frequency devices. It also details requirements related to marketing devices that fall under the scope of Part 15.

The message is fulfilling the requirements set forth in Section 19 of Part 15 of Title 47 of the Code of Federal Regulations. The basic meaning behind this message is that your device does not have priority status in any given frequency range. To legally operate any device that bears that message, you must follow the two conditions.

To comply with the first condition, if your device is causing harmful interference you must cease operation of that device. Harmful interference is generally any emission that interferes with radio navigation services, safety services, or any other licensed radio communication. If you receive notice from someone, the local fire department for example, that your cordless phone is interfering with their radios, you must stop using that phone or take measures to prevent the interference.

Compliance with the second condition is much easier as there is not much action required by the user. It doesn’t necessarily mean that there will be interference that you will have to deal with or anything of that sort and does not mean that you cannot take measures to prevent interference. For example, you can install filters between your wireless router and the antenna or try running your wireless network on a different channel.

The way it affects you, though, is that if, for example, radio signals from the local fire department are causing problems with your wireless network, the fire department would not be at fault and there wouldn’t be much you can do about it. Since the fire department is licensed for the particular frequencies that they use, they have priority.

Now, in most situations, it’s not very likely that you are going to have interference issues, but if they occur, the user of the device with that message is legally the one who has to deal with it. If that device is causing the interference it must be shutdown and if it is the victim they just have to deal with it. Seriously though, how many devices do you have that bear this message and how much interference have you experience them either receiving or causing.

If you would like to check out Part 15 for yourself, the link to Part 15 is in the table of contents of Title 47 at the FCC’s website.