An unintentional radiator has to meet certain criteria to be part 15 complaint. A nasty noise source in the AM band is compact florescent light bulbs (CFLs). If I have a light fixture with 3 sockets, I can put 3 CFL’s in it. I could have two of that fixture in a room. So, if each of the CFL’s were just barely part 15 compliant for noise emissions in the AM band, I am now 6x above the limit since I have 3 bulbs in 2 fixtures. No one would care. No FCC agent will come into my house and ask to see my CFL bulbs. They are not going to take a field strength meter to the fixtures. They are not going to look at the noise radiated by the power line because of the CFL’s.
On the other hand, if I were to take two 15.219 compliant transmitters, put them next to each other on the same frequency, making sure they were on the exact same frequency so they added together perfectly, that would get shut down by an FCC inspection.
I am not saying 15.219 or 15.239 transmitter clustering should be allowed, but if the FCC wanted to fix the AM band they should adjust the unintentional radiator limits to be mindful of how groups of radiators end up clustered. A light fixture may have 3 bulbs. A switching power supply power brick will probably be on a power strip with some more power bricks. Ethernet cables tend to get run in parallel in bundles, and so on.
Right you are, stvcmty.
It is easy to see that the FCC is not planning to tackle the interference problem from CFL bulbs, but are talking about SWAT teaming small micro broadcasters without bothering to exclude part 15 with their rhetoric. That suggests our "interference" is more unwanted than buzzy bulbs.
Hell, band smothering IBOC blasters are wiping out their own commercial service by being so noisy even old time listeners are moving away. No one buys a digital radio, there probably aren't any digital radios to buy.
Yet in the dreamland of corporate radio if they really believe smothering small stations will improve their bottom line, they are on life support ready for hospice.
AM reception inside my home, except for that transmitted by my indoor transmitter, is not possible because of electrical noise. This noise was present here before CFLs were in use and comes primarily from light dimmers.
The old tech's trick of checking that an oscilloscope probe is working of touching the tip of the probe is enlightening. In the "good ole days" one would see a fairly good sine wave but this is not so today. There are all sorts of odd waveforms mostly synchronized with the the power line frequency displayed.
My solution for my ham and short wave interests is to use an outdoor dipole and I can then receive AM and SSB well, but since there is nothing on broadcast radio which I care to listen to I wouldn't bother with an outside antenna except for needing it for my other interests.
I am beginning to wonder if, except for the broadcasters, many care about AM reception or interference. As mentioned above, IBOC amounts to the broadcasters interfering with themselves and ignores that even digital radio is not immune to interference.
Neil
There is content on AM. Yesterday I wanted to listen to the TOR/KC game on my drive home. The only place I could find it was AM radio. In the Baltimore are, there are at least 3 AM stations that play music that I listen to (810/970, 1330, 1370); they play slightly different formats than are on the available FM’s. There is plenty of talk radio on AM, but I don’t listen to that, so it does not draw me to the band.
Even in my car there is a noise source. If I turn on the rear window heat strips to defog/defrost my rear window, it kills my AM reception.
On my drive, there are some roads that have sections where AM is useless because of power lines.
Interesting on the MD stations. I've picked up 1330 and I think 1370 here in Elizabeth City, NC. I've also heard some music at night on 1500 or somewhere around there but was in the noise floor. With the Grundig I have a better chance of receiving AM than I did with my boombox. Keeping that in mind I'm hopeing that I'll attract listeners because o those who listen to music on AM looking for something the FM's don't provide. That would be the only way to attract listeners.
Hope for a power outage....then AM is the way it used to be
Mark