FM radio interference from planes

On Fri, 14 Jul 2006 16:43:15 -0700, "Peter Duniho"
wrote:

"Jim Macklin" wrote in message
news:ASVtg.68472$ZW3.9262@dukeread04...
If he is broadcasting and his power is above the proper
legal range, he MAY be in violation.

Again, since it seems you didn't catch it the first time I wrote it:

Assuming he's using an off-the-shelf device intended for the use in which
he's applying it, that's extremely doubtful

He should be sure the
FM transmitter he has, has an FCC number and is not causing
any interference with the neighbors.

Whether he is causing any interference with the neighbors is irrelevant. As
long as it's approved by the FCC (and any off-the-shelf device intended for
the use in which he's applying it would be), the neighbors are required by
law to accept any interference (just as he and I and other people in similar
situations are required to accept interference from nearby AM transmitters).


If it is a part 15 device (very low power no license required. This
includes the wireless mikes, remote speakers, remote weather stations,
WiFi computer networks, and a whole bunch of other *stuff*) the
*required* sticker on the back says two things. He *may not* cause
any interference and has to accept any he receives.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Pete

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Roger (K8RI)" wrote in message
...
If it is a part 15 device (very low power no license required. This
includes the wireless mikes, remote speakers, remote weather stations,
WiFi computer networks, and a whole bunch of other *stuff*) the
*required* sticker on the back says two things. He *may not* cause
any interference and has to accept any he receives.

What you (and the other responders) are failing to understand is that the
device in question is a TRANSMITTER. As such, it may very well interfere
with any other device, and such interference would be perfectly legal (as
long as the transmitter is operating within its legal requirements, a safe
assumption given the "off-the-shelf device intended for the use in which
he's applying it" qualification that started this subthread).

You cannot get a complete education on FCC regulations from a little sticker
found on the back of Part 15 devices.

Pete

On Tue, 18 Jul 2006 14:19:48 -0700, "Peter Duniho"
wrote:

"Roger (K8RI)" wrote in message
.. .
If it is a part 15 device (very low power no license required. This
includes the wireless mikes, remote speakers, remote weather stations,
WiFi computer networks, and a whole bunch of other *stuff*) the
*required* sticker on the back says two things. He *may not* cause
any interference and has to accept any he receives.

What you (and the other responders) are failing to understand is that the
device in question is a TRANSMITTER. As such, it may very well interfere
with any other device, and such interference would be perfectly legal (as

No it is not. The FCC is very adamant about the interference
interpretation.

long as the transmitter is operating within its legal requirements, a safe

That is the point! The "transmitting" device may not cause (is not
allowed to cause) interference even when it when it is operated fully
with in compliance to part 15. A number of companies are finding that
out the expensive way at present.

assumption given the "off-the-shelf device intended for the use in which
he's applying it" qualification that started this subthread).

You cannot get a complete education on FCC regulations from a little sticker
found on the back of Part 15 devices.

For part 15 devices that little sticker says it all.
The only thing you shouldn't have to worry about interfering with
would be another part 15 device.

As this one is operating in the FM broadcast band even if operated
within the limitations and his neighbors hear it and complain he'd
have to shut it down.

However the original post was not about the transmitter at all, but
him hearing aircraft radios through his system. That could be
intermod/front end overload, or images. As he's listening around 108
and aircraft are roughly 130 that gives a difference of 22 MHz which
shouldn't create an image problem unless one of the IFs runs in the 22
or 44 MHz range. So, I'd guess it's probably front end overload with
intermod.

I occasionally hear aircraft that would be transmitting on 126.45, or
118.45 on 147.00 MHz. However I'm directly under the GPS/RNAV 6 app
into Midland Barstow. Which means they are quite close to my antenna.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

Pete

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

"Roger (K8RI)" wrote in message
...
No it is not. The FCC is very adamant about the interference
interpretation.

Yes, it is. Just as the legal AM transmitter that's practically in my
backyard is not in violation of FCC rules when it bleeds into every
amplified electronic device in my house (and causes all sorts of other weird
issues too), so too is some other legal transmitter not in violation.

That is the point! The "transmitting" device may not cause (is not
allowed to cause) interference even when it when it is operated fully
with in compliance to part 15. A number of companies are finding that
out the expensive way at present.

Such as?

For part 15 devices that little sticker says it all.
The only thing you shouldn't have to worry about interfering with
would be another part 15 device.

Again, you are missing the point. Practically any device that is in the
neighbor's house that might be interfered with is a Part 15 device (as I've
already stated in this thread). The neighbors won't have any valid
complaint, as their electronic devices are all required to accept
interference.

Pete

That is the point! The "transmitting" device may not cause (is not
allowed to cause) interference even when it when it is operated fully
with in compliance to part 15. A number of companies are finding that
out the expensive way at present.

Roger, at one time I thought you had a grip on this radio and RF stuff. I'm
starting to believe not.



However the original post was not about the transmitter at all, but
him hearing aircraft radios through his system. That could be
intermod/front end overload, or images. As he's listening around 108
and aircraft are roughly 130 that gives a difference of 22 MHz which
shouldn't create an image problem unless one of the IFs runs in the 22
or 44 MHz range. So, I'd guess it's probably front end overload with
intermod.

Come on, buddy. The image is at TWICE the IF from the intended. With the
standard 10.7 MHz. IF of an FM radio, the image is at 21.4 MHz higher than
the intended frequency, exactly where we predicted the image would be. If
he's listening at 107. the image will be at 128.4, right where it was found.

Jim