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RE: Cordless phone interference and the law

For those who are interested. I've heard indirectly from the FCC. What
Riley Hollingsworth did was ask Ed Hare at ARRL to help me. I've included
his response with his permission.

>Hi, Steve,
>Riley Hollingsworth asked me if ARRL could provide any information on how
>do direction finding under the circumstances you describe.
>This is partly a Catch 22.  Telephone communications are protected from
>eavesdropping, so it would not be legal to listen to the phone
>and use that information to identify the source.  Of course, some
>listening may be inevitable; if your receiver is on FM, and you are
>for amateur communications and this unlicensed signal comes on, it may take
>while for you to recognize that it is not an amateur signal, but rather
>from an unlicensed user of amateur spectrum.  Under those circumstances, I
>can't imagine that you have done anything wrong, as long as the purpose of
>your listening is for legitimate amateur purposes, not to eavesdrop.
>The first question to ask yourself is whether the device is causing harmful
>interference.  In this context, it is defined as the repeated disruption of
>radio communications.  Merely hearing a signal in "our" bands is not
>interference. After all, how would we feel if our primary sharing partners
>30 meters or 70 cm said that hams had to get off the band because they
>sometimes hear us on "their" bands?  For harmful interference to occur,
>either the signal must be interfering with ongoing amateur operation or
>preventing such operation from happening.  Just as a couple of examples, if
>the satellite is in range and you are in QSO with another ham and this
>signal comes on and stays on long enough to prevent your QSO from
>that is, IMHO, harmful interference.  OTOH, if the satellite is not
>and you are not using that part of the band, but turn on your receiver and
>hear the unlicensed signal, that is not harmful interference, as defined by
>the rules.  If you were in QSO and an unlicensed signal transmits for a
>every few minutes, it would be a judgement call about whether it is harmful
>interference or not.
>There are three sets of responsibilities involved here -- yours, the
>unlicensed equipment manufacturer and the operator of the unlicensed
device --
>in all likelihood a neighbor.  Your responsibility is the easy part -- you
>need to ensure that your complaint, if any, is indeed based on actual
>interference.  If you are equipped to operate the satellite and this signal
>preventing that much of the time, I believe it to be harmful interference.
>The equipment manufacturer is required to meet the FCC
>requirements -- Certification for an intentional emitter.  On 2.4 GHz,
>authorized equipment can use power levels that can be heard by sensitive
>amateur receivers for distances of up to several miles, even for
>non-spread-spectrum transmissions. It is quite likely that the phone is
>and that the manufacturer has met its responsibilities.
>Under the rules, the operator of the device is responsible for doing so in
>way that does not cause harmful interference. Of course, this means that by
>whatever means, you will have to track him or her down.  Now, if you
>*incidentally* happen to recognize the voice as a neighbor when the signal
>first pops up on your band, you would not have to eavesdrop at all to
>the source.  If not, however, and you really can't legally listen to the
>signal until you get a name or street address, you may have to use some
>direction finding techniques to identify the operator.  Fortunately,
>good directivity on 2400 MHz is relatively easy, and you may be able to buy
>build a small Yagi and do some triangulation.  You may be able to use a
>receiver's S meter as a strength indicator to triangulate the signal with
>audio turned off. If you use SSB or narrow FM modes to detect the signal,
>may be so distorted as to be unintelligible and if you can't understand the
>words being spoken, you really are not eavesdropping to use the distorted
>audio as an easy means of determining relative field strength.
>Once you do find the operator, tread lightly. To your neighbor, they went
>the phone store and bought a product being legally sold on the open market
>for a total stranger to knock on the door and tell them that they are
>violating federal law by using the phone will be difficult for them to
>While you may ultimately have to approach a neighbor, put on your best
>and make the initial contact a positive one.  If you would find it helpful,
>ARRL can contact a neighbor by letter, although in some cases, a local
>approach is best.
>Let me know how I can help.

>> I heard from the FCC, specifically from Riley Hollingsworth and I'm
>> surprised at the response. Riley is going to research ways that I can DF
>> cordless phone interference without listening to the voice. I assume that
>> means that it's illegal to listen to cordless phone transmissions even if
>> they are in our amateur bands.
>> I don't know what else to say, I'm kind of baffled by this. I guess I'll
>> wait and see what he comes up with.
>> Steve .. AI7W

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