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I've googled around a bit and here are the interpretations I've found in non-authoritative sources:

  1. that the device is unable to filter out interference caused by other certified equipment
  2. that if there is interference, the device must not "complain" about it (whatever that means)
  3. that if there is interference and your device fails to work, you must not complain about it (i.e. you cannot sue for failure to perform the function)
  4. that if there is interference, the device can't do anything about it (though I can't think what it possibly could do about this other than actively seek out the source and shut it down, sci-fi style)
  5. that the device is actually required to work correctly regardless of any interference

So what does this phrasing actually mean? Is it phrased poorly or am I misunderstanding it as a result of not being a native speaker?

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    \$\begingroup\$ What would it mean to say that a device does not accept interference from other sources? Would a device operating in a Faraday cage be such a device? \$\endgroup\$
    – Aaron Hall
    Jul 24, 2014 at 21:56

2 Answers 2

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"Interference" in this context applies to one, radiated RF signal affecting the reception of another radiated RF signal. The interference is not produced within the interfering transmit system, but as a result of the radiated field intensity it produces at the receive location(s) of other transmitted signals.

Transmit systems whose operators and equipment are specifically licensed/certified by the FCC, and are operating as permitted by their station license are protected from such interference from "Part 15" unlicensed operators and systems — even when those unlicensed operators/systems strictly meet the technical requirements set out for them in FCC Part 15 rules.

This FCC protection from interference applies only to certain electronic devices using the RF spectrum. For example, the user of an audio amplifier in a home stereo system may hear the programming of a licensed AM broadcast or HAM radio station located physically nearby. But there is no FCC recourse. S/he must either accept that interference, use an amplifier that doesn't exhibit that issue, or relocate that stereo system far enough away from the transmit system so as not to be affected by its legal operation.

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  • \$\begingroup\$ So basically answer # 3 in the question: that if there is interference and your device fails to work, you must not complain about it (i.e. you cannot sue for failure to perform the function) \$\endgroup\$
    – Dzmitry Lazerka
    Aug 2, 2020 at 4:19
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FCC Title 47, Part 15 section 5.b should clarify this for you:

(b) Operation of an intentional, unintentional, or incidental radiator is subject to the conditions ... that interference must be accepted that may be caused by the operation of an authorized radio station, by another intentional or unintentional radiator, by industrial, scientific and medical (ISM) equipment, or by an incidental radiator.

In other words, to be FCC listed under part 15, your device must operate normally when subject to normal, authorized RF emissions from other sources.

You can drill down to the specific requirements under part 15 by starting here:

http://www.fcc.gov/encyclopedia/rules-regulations-title-47

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    \$\begingroup\$ How does that relate to the fact that the operation of many devices can be affected by mobile phones which are placed extremely close to them? A mobile phone which is placed directly on top of a guitar amp will often cause the amp to produce annoying sounds, even though the level of radiation produced by the phone is well within the legal limits. My interpretation would be that the users of the amp have no cause of action against the phone maker; if they don't like the interference, they should move the amp or the phone. \$\endgroup\$
    – supercat
    Dec 31, 2012 at 19:53
  • \$\begingroup\$ @supercat There is much more that could be said on this topic. The issue is that GSM phones have a particular time slicing transmission scheme which may result in nearby audio equipment picking up the lower frequency electrical noise. It's possible to make audio equipment that is immune to these emissions - all "made for ipod" devices for instance must reject this noise and have clear audio when right next to an iphone. However this certification doesn't necessarily mean that the end user must not notice the noise to be certified. \$\endgroup\$
    – Adam Davis
    Jan 2, 2013 at 15:11
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    \$\begingroup\$ That can't be correct, because consumer devices that fail to operate correctly in the presence of licensed radio transmitters (such as a neighbor's licensed ham radio transmitter) are not taken off the market for failure to perform. The correct interpretation is that the human operator of a Part 15 device has no legal right to require licensed operators to stop or correct interference to his device originating from the licensed service, and has a duty to correct or stop any interference to a licensed service originating from his device. \$\endgroup\$
    – Paul
    Jan 6, 2013 at 19:29
  • \$\begingroup\$ @supercat If iphone owner were visiting a broadcast radio station, and the iphone was adding noise to the broadcast, the broadcast licensee would be within their legal rights to require the iphone be turned off or otherwise stop interfering. Ultimately, the FCC could fine the iphone owner on complaint from the licensee. If the iphone owner works across the steet from a broadcaster, and the licensed broadcast transmitter somehow prevents the iphone from working properly, the iphone owner does not have a valid complaint. For examples, see arrl.org/part-15-fcc-enforcement-actions \$\endgroup\$
    – Paul
    Jan 6, 2013 at 20:23

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