The FCC doesn't enforce their own rules on not causing interference. Maybe if the big corporations that own the stations and pay big money for licences spoke up maybe it would change.
Haven't had noise on FM personally.
Fortunately most noise is amplitude modulated and the FM audio is frequency modulated so all FM receivers can remove the noise, which is the AM rejection spec. with an FM tuner.
Where with AM the noise and audio broadcast can't be separated.
Mark
You'd be amazed how weak FM really can be. The big gain is honestly the frequency, check out the aircraft band up above 108 MHz its all AM and noise free. (Mostly, theres still noise in VHF-Lo.)
It is pretty neat hearing ligtening crashes On the FM band though.
When lightning is dangerously close I've heard it on an FM Radio. Even a good receiver like a Carver, Yamaha or Rotel I've heard it. However back to topic of QRM. These power supplies are starting to be horrible. Instead of going after part 15ers for slight overpowered stations lets get rid of the real noise. Imagine that if we clear up the noise we'd get the range we want without increasing power much or if at all? That would be the kick in the pants. Maybe again going after Radio manufacturers who make Radio's that don't have proper filtering. I had an IC chip Walkman back in 1992 that had a super good FM tuner in it. I even thought of using it for my Stereo. It really had the selectivity of a Car Radio. Problem was that the mini 1/8th inch jack was really cheaply made. I've never seen a Radio like that as a portable before. It was made by Toshiba.
Thats where I think radio's biggest problem really lays, the ever increasing noise floor. If the noise problem could be solved the AM band wouldn't be struggling so bad now.
If the noise floor could be reduced to the level it was in the 70s I'll bet you could get a mile even with the Talking House AM transmitter on a wire and running out of box power of 92.5 mW. The reason it can't do it now is because of the high AM noise floor. There would be little need for more power at that situation. Too bad we can't get the FCC to do that. Then everyone would be happy.
Right on! The noise just emanating from the AC power has killed AM! As I have said in past rants the FCC, Industry Canada, and the public just don't care. How come the corporations with a lot of influence on the government and pay a fortune for a broadcasting licence don't say anything?
Mark
"...The noise just emanating from the AC power has killed AM! ...
Just to note that in my home in a small-ish city of 41,000 and using cheap AM broadcast receivers, I can quite easily listen to Class A AM broadcast stations in the daytime as far as 200 miles away from me -- and at night from at least 700 miles away.
It's worth knowing that AM noise conditions are not the same everywhere.
Right now things are very quiet here in the population center of a 2.5-million population area, but it hasn't always been this way, and sometimes the noise came from me!
The worst year was when a faulty turn-on device on a streetlamp 500-feet away sent a recurrent 2-minute buzz that stopped, started quietly and grew to a super-loud noise all night from about 1400 to 1700 kHz. I finally went out and located the lamp, but before I got around to reporting it it got fixed.
There is a switching power-supply right over in the other room that wipes out my 1550 kHz signal on one radio in particular.
There is a hallway LED bulb that splats badly on longwave, getting weaker up into the AM band.
Later tonight if I remember to do it I'll tell a true story of a super-killer noise source with which I established a gentleman's agreement! Great story. Tune in later.
In the year 1970 I operated an audio recording studio on the second floor of a 2-story commercial building, the downstairs space had different businesses over time.
At first there was a sound company that rented big PA sound re-enforcement gear for public events and we did a lot of work for each other.
Next was a used bookstore, and I am ashamed I never went in to browse, I am a book lover to this very day.
Third came a 1-man arc welding service, a super talented guy who did arc welding at an artistic level, he was very good. He'd previously worked for McDonnell Douglas Airplane Corporation, and decided to risk having his own business.
Trouble was, arc-welding is done by producing a major electric arc of electricity which melts metal, and that beast put out RFI (radio frequency interference) so strong it actually induced its way into my audio equipment and totally blasted my dainty little voice over work.
Here's how we solved it. I met with the guy, explained the problem, and we agreed that while I was holding a recording session he would postpone his arc welding until I gave him an all clear.
This worked because only a small amount of time was spent actually recording... when it came time to edit and produce my tapes I waited until he locked up and went home at 5-o'clock or waited until the weekend when he was closed.
Sadly he went out of business because of inadequate promotion... he just didn't attract enough customers.
After that I rented the downstairs space myself and expanded the size of my operation.
Fast forward to now, here we are as group owner of several part 15 radio stations currently on the market for over a billion dollars.
Great story Carl, and you might get that kind of money once all of the LPFMs and translators run out. They'll have to come to you, so you might be sitting on a gold mine.
If you get your asking price of over a billion dollars, how will you spend it in your lifetime? In the other post where you were building your Ramsey FM transmitter, someone said that you were 115 years old, and the fact wasn't denied.
No one could spend that much money, in the presumed time they have left, but it could be helpful in the ALPB's coffers! Consider a donation of stock.
Good thinking, Nate Crime, and I don't plan to try spending so much money. First thing I want to have it all delivered in one-dollar bills so I can stack it in the house and make aisle ways through all the stacks, maybe make a maze.
It is appealing to give a chunk to the ALPB, but if they get too much they might get big headed and turn to lavish life-styles with private jets, Swiss resorts and shady dealings.
I was also surprised to hear that I am 115 years old. Seems amazing given the drinking and snack food binges.
Part15(dot)us could use new furniture, and we might start a returement center for old Part 15 hobbyists.
Oh, and I'll expand my Low Power Radio School for Women.
Until the sale can you advance me a five?
The article linked in Post # 1 by Tim in Bovey refers to indoor noise on the FM band in particular.
I notice that a few of us drifted into general all-band noise comments, but I just re-read the original article and must admit...
I did not realize that the FM band is so noise-laden, and no wonder.
As the author mentions, the nature of FM radios MASKS the noise, it doesn't make it not exist! Huge difference.
Next time I turn on my spectrum analyzer I'll watch whether I can spot the noise floor on the FM band.
By the way, our biological bodies including our brains are swimming in this so-called noise, which in fact is electro-magnetic radiation, and maybe that's why everyone has gone insane.
Just saying.
"As the author mentions, the nature of FM radios MASKS the noise, it doesn't make it not exist! Huge difference."
Exactly....and that's all that matters! Noise always existed in the FM band of frequencies BUT the noise can be almost eliminated because it can be separated from the audio since most noise is amplitude modulated. This is done at the detector stage of all FM receivers.
Mark
Bear in mind the noise floor despite not being specifically audible still reduces signal strength and does reduce range quite significantly. This is why the public safety world is quickly abandoning VHF, just like they abandonded Low Band (46 MHz) and the 1600-1700 kHz band before that.
FM is getting increasingly stepped on, the newest problems coming from traffic signals which ruin CB reception and blanket the FM band (only on Red so far). Other problems are starting to come from powerlines as well, the biggest offenders are by and large the darned traffic lights.
The noise is why Digital TV doesn't work on VHF-Low.