Become a fan of Slashdot on Facebook

 


Forgot your password?
Close
typodupeerror
×
United States

Why does FCC Require the Acceptance of Interference? 14

Posted by Cliff from the if-I-can't-put-it-out-why-can't-anyone-else? dept.
Goat Milk? asks: "I was just wondering if someone knew why on most electronic devices it states that it must not create unwanted interference, but also say they must accept any unwanted interference. Why must they accept it? Who does it benefit for my hardware to accept interference?"
This discussion has been archived. No new comments can be posted.

Why does FCC Require the Acceptance of Interference? More

Why does FCC Require the Acceptance of Interference?

Comments Filter:
  • You've heard of grandfathering, right? Well, this is just mother-in-lawing...

    (ducks)

  • Seriously, I always thought that bit was a sort of safety net for electronics manufacturers. I.e. "if you are getting interference, you cant blame us."

    I think this bit only applies to a certain class of devices, or maybe others, but not all. I've never read the passage in question, but I think there are other types of devices where they "do not accept interference" or "should not accept interference". Clearly there are some electronic devices which DO cause "harmful interference".

    In fact, the Part 15 rules ("will not cause harmful interference, must accept harmful interference") sounds a lot like the Internet protocol guideline of "strict in what you send, robust in what you accept".
    --
  • it basically states that so the device must recieve the unwanted interference but not RADIATE out more interference as a result of malfunctioning operation. If you use a HERF gun on your computer, it must not blast you back with a radiated EMP shockwave caused from the frying of its internal components. basically, its to prevent a room full of electronics going beserk the minute they recieve a pulse from an unwanted source. you really dont want your FCC class B radio to destroy your TV & computer if it gets a voltage surge thru the mains.
  • This used to be a question on the FCC first class license exam.

    There is a hierarchy of certifications, based on the utility of the device to the public good.

    At the top is civil defence and emergency communications. Nobody can interfere with them. They can interfere with just about anyone and get away with it.

    Then comes public safety, such as aeronautics comms, police and ambulance. Nobody should interfere with them, but no guarantees. Pilots occasionally note some interference from government comms, but can't do much more than switch to another frequency.

    Further down the list are public broadcast stations, radio and TV. They are also serving the public good, unless you look at their bland content :-) Normal people should not be interfering with TV broadcasts, this means your power drill or computer interfering with your neighbors soap opera is a bad thing. If your neighbor complains, you must stop using your drill or switch off your computer.

    At the bottom of the shitpile is consumer electronics. If a TV transmitter is interfering with your gear, tough shit. You have to accept the interference. No complaining. Your device also can not create any interference with any of the more privileged services such as airplane radios or emergency comms.

    the AC
  • There is no way to totaly eliminate electroinc interference. The FCC knows this. When they say your device must accept unwanted interference, they mean that it should be able to absorbe it and keep doing what it's suposed to. Kind of like Timex(r)- it needs to take a licking and keep on ticking..
  • Frequency allocations are specified by the ITU and the FCC (in the USA). It is common to have multiple services (radionavigation, amateur, police) assigned to a given frequency band. There is usually a hierarchy of primary and secondary services. Secondary services are not allowed to interfere with primary services and must accept interference from the primary services. Consumer electronics equipment is usually at a level even lower than the secondary services. The general idea is to allow multiple services to share a frequency band, with a set of rules that says who wins if there is a conflict between two services. For example, some of the wireless LAN products share frequencies with the amateur radio service. The FCC rules give the amateur radio service precedence over "part 15" devices, such as wireless LANs, in this frequency band. If my amateur radio station wipes out your LAN, assuming I am following the FCC's regulations and technical standards, that is your tough luck. If your LAN causes harmful interference to my amateur radio station, I can (theoretically) get the FCC to order you to cease interference with my amateur radio station. Each frequency band has an associated list of primary and secondary users and rules on who wins in disputes over interference.
  • Why must they ACCEPT interference? Not why am I at the bottom of the priority list.

    They can not Interfere, fine. Sensible. My wireless LAN should not shut down military communications, police communications or broadcast systems.

    Let's say you have an amateur radio station next door, and I can pick your transmissions up with my TV. Why can't I shield the TV from your transmissions ? Why should I accept the interference ?

    Is there a technical reason why having my TV reflect your transmission would cause the network to fail ? The requirement of acceptance seems to me to indicate that perhaps the sheilding itself may cause interference ? Is that true ? If so how is the interference caused, and how does it manifest ?

    Is it merely a problem of wording ? It sounds like any device that produces appropiate emmisions should interfere with my consumer devices, and that my devices are required to accept this interference.

    If I were just a mite more paranoid, I'd assert that the government wants to make sure they can shut down and monitor my electronics.

    Then again, maybe they do. Of course I could be paranoid...am I paranoid enough ?

  • Required acceptance (Score:2)

    by Anonymous Coward
    The statement about having to accept interference is there so you understand your rights (or more specifically the rights you dont have that you might have assumed you have) Specifically what accepting interference means is that if my cell phone crashes your computer, its is your responsibility to fix your computer. You cant make me not use my cell phone because you want to use your computer. This used to be a big deal in ham radio circles. Bad radio transmitters would radiate harmonics which would mess up your neighbors TV. This was the hams problem since he was transmitting signals he was not supposed to. Unfortunatly good radio transmitters would also mess up your neighbors TV if was not well designed. This was a public relations disaster for hams because the average person does not understand (or care) about the difference between those two cases. They just want to watch the football game and you are keeping them from doing that. For years the American Radio Relay League tried to get the FCC to require manufactures of consumer electronic equipment to make stuff that worked in the presence of radio transmitters. I dont know what became of that effort, but I suspect that the "required to accept interference" clause is a result of that lobying.
  • When the FCC says "accept interference", they mean that you do not have a legal recourse. You are free to attempt to fix the problem by shielding or moving your TV. Just don't go to the FCC and demand that they shut down a frequency user with higher precedence. The notice is just a way of saying that you are allowed to use the device with the understanding that you can't interfere with existing spectrum users and if they interfere with you, you will have to live with it. Think of it as flying standby on an airplane. If the space is available, you get to fly. If someone with a normal ticket wants your seat, you get bumped off the plane.
  • I do run an amateur radio station and run into this all the time. I interfere with peoples TV's when I transmit over a certain power on certain frequency bands. that's life. Your TV reciever is too cheap to filter out the strong signal coming from my equipment, which is overpowering the signal from the TV station.

    I've also had it the other way, where a neighbor had a device interfering with my equipment.. their microwave was leaking, but they wouldn't fix/get rid of it. After a letter from the FCC, that they didn't answer, acouple of nice men in black suits showed up, siezed her microwave, and fined her afew hundred dollars for having an unlicensed transmitter.
  • Specifically what accepting interference means is that if my cell phone crashes your computer, its is your responsibility to fix your computer

    OK.... but replace "computer" with "life support system".

    Of course, I guess in turn, you can't ask the hospital to turn off its cell jammers if they are denying your cell service.

    (Hey... if I get a cellular modem for my Palm, can I sue the hospital for DOS? :) )
    --
  • Normal people should not be interfering with TV broadcasts, this means... If your neighbor complains, you must stop using your drill or switch off your computer.

    Hold on -- isn't a TV also a Part 15 device, and therefore must accept any unwanted interference?

    If the way you put it is true, that means the people upstairs will never be able to vacuum.

    I think this might apply to interefering with broadcast transmissions on a large scale, not on random interference. I'm certainly in trouble if I, say, interfere with HBO's feed and display a message saying their license fees are too high.
    --
  • Life support systems are far higher on the "FCC food chain" than computers...
  • You're largely correct.

    I am a ham, and I ran into a situation where only one neighbor in an apartment complex (out of about 9) was complaining about interference, and he was complaining about his stereo, his computer speakers, his cordless phone, his clock radio...you name it. He said he was going to get me shut down if I didn't simply stop transmitting -- since I was transmitting, and "wasn't allowed to interfere", I had to *stop*.

    This is a case of IANAL-syndrome biting someone in the tuchis. If he had bothered to READ the law (which I supplied, photocopied, with a pamphlet from various Amateur Radio sources), he would have seen that, since my radio was in good working order, properly radiating in the right bands, that he was S.O.L.

    A ham is not responsible for consumer electronics picking up PRIMARY interference -- not spurious emissions -- because the device receiving it is considered to be MALFUNCTIONING if it is receiving signals outside it's intended band of operation. A cordless phone should receive signals ONLY in the cordless-phone bands, not ham bands. A stereo or clock-radio should only receive AM and FM broadcast. And computer speakers shouldn't receive ANY. If it is, it's NOT the transmitter's problem, it's the cheap-ass equipment manufacturer who thinks plastic is RF shielding that's at fault.

    --- Gwen, KB3DVJ

Slashdot Top Deals

He has not acquired a fortune; the fortune has acquired him. -- Bion

Close