Regulating RF from LED lighting

[radioskeptic]

AM radio has been plagued with interference from LED traffic lights for some time. But now LED lighting is being marketed for commercial, industrial and even residential uses.

The record of fluorescent lighting shows that RF can be suppressed. Most commercial and industrial fluorescent fixtures put RF noise into the AC supply, making it impossible to use AC-operated AM receivers in many locations. On the other hand, the 50-year-old, 32-watt “Circline” (TM?) fixture on my kitchen ceiling creates no interference at all. I have to stand on a chair and hold a portable radio within a few inches of it to hear any “fluorescent” noise at all, even between stations.

Contemporary “compact fluorescent” bulbs from major manufacturers have very good RF suppression, too, though some off-brands from dollar stores are as bad as industrial fluorescent fixtures.

Fluorescent lighting takes, on average, only 40 percent of the power need to attain the same level of illumination from incandescent bulbs. But LED lighting takes on about 25 percent of that, or 10 percent of the power needed by incandescents.

Perhaps more important, advances in LED technology promise better color rendition than even the best modern fluorescents—or even a perfect match of the truly warm look of incandescent lighting, if that’s what you want.

For now, the market for LED lighting, especially in homes, is limited by the high initial cost. But that’s bound to come down eventually to the point where both the energy savings and the long life of LED bulbs make LED’s an attractive alternative, especially when they can offer superior color rendition.

We should act now to prevent extensive interference to AM radio. The band can’t stand another such electromagnetic assault.

Shouldn’t someone, perhaps the NAB, petition the FCC to bring all lighting under Part 15?

 

[KeithE4]

Don't hold your breath waiting for this. With the number of listeners bothering with AM dropping (literally - they're dying of old age) by the year, there is almost no need, Part 15 regulations notwithstanding. If there was a market for AM, I would think a DSP chip in the IF section would take care of most of it.

But the need is just not there anymore. There are more people that want energy-efficient lighting and lower electric bills than there are that want to listen to Ancient Modulation. This is 2011, not 1961.

 

[radioskeptic]

KeithE4 said:

Don't hold your breath waiting for this. With the number of listeners bothering with AM dropping (literally - they're dying of old age) by the year, there is almost no need, Part 15 regulations notwithstanding. If there was a market for AM, I would think a DSP chip in the IF section would take care of most of it.

But the need is just not there anymore. There are more people that want energy-efficient lighting and lower electric bills than there are that want to listen to Ancient Modulation. This is 2011, not 1961.

What a smug, arrogant and puerile post! You wouldn’t be so cavalier about the RFI problem if you owned an AM station, Keith. Let me answer you point by point:

(1) AM is more than right-wing talk. Sports radio attracts a younger demo, and they’re not dying off. (A guy whose R-I signature line reads “We have to save the Earth! It's the only planet with football and beer” should know that.)

(2) There’s almost no market for stand-alone radios. Plenty of 20- to-30-year-old radios still work just fine. And car radios? People are keeping their cars longer in this economy. Assuming DSP’s could cope with all the RFI that afflicts AM these days (a doubtful proposition!), it would be several years before that could solve AM’s problems in cars.

(3) Ancient Modulation? AM is used in VHF air traffic control precisely because the capture effect in FM is more of a liability than an asset in that application! And a modified form of AM called vestigal sideband modulation (VSM) was used for OTA TV video right up until the analog shutoff.

(4) And of course, we all have calendars, so we know what year it is.


I also see that you’re a ham radio enthusiast. I guess you’re one of those guys who stick to two-meter FM because HF AM is a little too difficult.

 

[radioskeptic]

I forgot to mention one important consideration in my original post:

All fluorescent lights contain mercury. For that reason, all burned out fluorescents are considered hazardous waste. The “compact fluorescent” (CF) swirls that screw into the ordinary sockets designed for incandescent bulbs are no different from long straight tube and curved tube (“Circline”) fluorescents.

LED’s, like incandescent bulbs, have no mercury. So I’ll go out on a limb here and predict that the CF age will be much shorter that the incandescent age. As soon as the cost of LED units is low enough that it’s roughly the same in cost per hour of operation as CF’s, the government will be trying to get CF’s phased out because of the mercury disposal problem.

So we'd better get the LED RF problem under control as soon as possible.

 

[K6JHU]

LED RF ?????

LED's run off of DC. It's the power supply that is making the electrical noise.

 

[radioskeptic]

Yes, but many of the LED fixtures, and the self-contained screw-base units that fit sockets for incandescent bulbs, use switching power supplies, which can create a lot of RFI. But that RFI can be suppressed, and we need laws or regulations of some sort requiring the suppression of RFI from switching power supplies -- not just from those in LED's and some modern fluorescents, but from the switching power supplies in all kinds of devices.

And if I'm right about the government doing a u-turn on CF's because of the mercury problem, LED lighting will create a much bigger problem than the switching power supplies in computers have so far.

 

[TomT]

There is a law. Part 15. Of course, this assumes the FCC cares about enforcing interference regulations. But they have to do more important things, like check public files for "issues" filings that no-one ever reads. Or eliminate over the air TV so we can all stream movies to our I-phones.

 

[KeithE4]

What a smug, arrogant and puerile post! You wouldn’t be so cavalier about the RFI problem if you owned an AM station, Keith. Let me answer you point by point:

You didn't mention that you own an AM station. Given that you have a vested interest in keeping the AM band as clear as possible, I can understand your viewpoint. However, I stand by what I said. I speak as a listener who you and your fellow station owners have to attract. Other than maybe 2 or 3 stations per market (and I have no idea how well you're doing because you didn't go into details), most AM stations are irrelevant outside of maybe a few hundred or maybe a few thousand listeners each that are attracted to the specialized formats that many AM stations carry - everything from Radio Disney (and The Mickey Mouse Outfit is finally starting to wise up to the huge waste of electricity that those AMs are) to paid religion and ethnic programming.

(1) AM is more than right-wing talk. Sports radio attracts a younger demo, and they’re not dying off. (A guy whose R-I signature line reads “We have to save the Earth! It's the only planet with football and beer” should know that.)

You didn't specify what station you own, what your format is, or what your target audience is. I wish no ill on you and hope you are doing well. But outside of sports and a "right-wing talk" format that will collapse the day Rush Limbaugh decides to retire, what else does AM have to offer compared to FM or streaming?

And, BTW, have you noticed that many big-market news/talk and sports stations are moving to, or are simulcasting on FM? I don't think I have to elaborate.

(2) There’s almost no market for stand-alone radios. Plenty of 20- to-30-year-old radios still work just fine.

Yep. I own several of them, including one that's 50 years old. Still works, too. Too bad they can only get two stations in my market (Phoenix) with a decent signal after sunset - Right-wing talk and sports on 550 and 620, respectively.

And car radios? People are keeping their cars longer in this economy. Assuming DSP’s could cope with all the RFI that afflicts AM these days (a doubtful proposition!), it would be several years before that could solve AM’s problems in cars.

And how many of those car radios are tuned to AM? A small percentage, I'll bet. And most of those are tuned to either the station that's carrying a local ballgame, or maybe Michael Savage or a delayed broadcast of Sean Hannity, Glenn Beck or one of the other right-wing blabberers.

And has anybody tried a DSP circuit in a commercial/mainstream AM radio? I have no idea. I don't own one that has it. Are any are even available other than expensive ham rigs?

(3) Ancient Modulation? AM is used in VHF air traffic control precisely because the capture effect in FM is more of a liability than an asset in that application! And a modified form of AM called vestigal sideband modulation (VSM) was used for OTA TV video right up until the analog shutoff.

Apples and oranges. The capture effect of FM is something that could be a potential disaster in the aircraft band. What is an advantage in broadcasting would be detrimental in a band where everybody has to be heard.

(4) And of course, we all have calendars, so we know what year it is.

Fair enough.

I also see that you’re a ham radio enthusiast. I guess you’re one of those guys who stick to two-meter FM because HF AM is a little too difficult.

You're getting on me for being arrogant?!?!?!? I haven't owned a two-meter rig in 15 years. I hold an Advanced Class license that I passed in 1972, when I was 17. 90% of my ham operation over the last 40 years has been below 29.7 MHz.

And full-carrier AM on the HF bands died out 45-50 years ago, except for a relatively few die-hards. But again, that's apples and oranges. Amateur radio has to make room for everybody, including AM ops, by definition. Broadcasters have to be where the listeners are. Only 25% (at best, even with sports) are on AM.

I really didn't mean to sound harsh, but I stand by what I said, and will continue to do so unless somebody proves me wrong. Again, I didn't know you were an AM station owner since you didn't say so, but you should have admitted you have a financial interest in what you are advocating. You didn't do so.

And, in the interest of full disclosure, I'm 55 - a member of the last generation that listened to music on AM - have spent 35 years in electronics manufacturing, and have had my ham license since 1970. My real name and callsign are published on every post I make.

 

[Tom Wells]

Ahhh, one of my favorite subjects, Part 15 regulations, and what do they really mean?

The origin of this was in the 1920s when many people used "bloopers", oscillating sets that
could be "turned up" in sensitivity until the radio itself was actually putting out energy on the same frequency
that the user was trying to listen on. But since the freq was a little different, there was a beat note
created that others would hear for miles. Multiply this by hundreds and the band became a howl of moaning,
squealing beat notes. All efforts to educate the public to not overdrive such receivers was useless.
Many things were done to improve the situation. The introduction of the superhet was a big help.
But it still contained a local oscillator, and the FCC began to require that the amount of energy this oscillator
generated would be so low that its output would not interfere with reception of any signals beyond
a very small range. The intent was to make radio workable for all, even those in apartment buildings.

The circuits at that time were of course all analog sinewaves, and did not create wideband RF products.
So part 15 rules were incepted with sine-wave signals as their first target.

An extreme example of local oscillator supression was found in military radios where the RF input was fed through a bridge circuit and filtered to ensure the local osc could not be detected at all, ever, by the enemy.

So the intent of part 15 rules are to ensure that such signals "become irrelvant" within a calculated distance.

When TRIAC lamp dimmers were introduced, the squared-off wave clipping created RF byproducts
at a much higher level than were ever created by radio or TV oscillators, over a wide range of frequencies,
AND send them back out into the wiring of the house to ruin reception over a wide area.
The difference between sinewave and squarewave noise has, as far as I know, has never been acknowledged.
Neither has the same issue been acknowledged with any switching-type power supply devices.

As others have noted, if you can't use such devices in the home without destroying AM reception,
its pretty clear the part 15 regulation as written is worthless and needs revisiting to address the
more destructive nature of RF created by switched-AC devices.

Modern flourescents have switching power supplies in order to make even more noise than just the
gas-discharge hiss, now they can make the 60hz buzz-saw too.
The old flourescents had a heavy laminated-steel ballast that used and transformed energy in a sine-wave
form. The new way is the electronic buzz-saw.

I'd sure love to hear an opinion from the FCC on why the wideband splatter of switching devices is OK
to let fly, when the emiission level of (from) new AM radios still seem to be truly compliant with the
Part 15 regulations.

LEDs themselves make no RF, but there are hundreds of boneheaded ways to make them and the circuit they are in
generate RF trash.

 

[radioskeptic]

To KeithE4:

You didn't mention that you own an AM station. Given that you have a vested interest in keeping the AM band as clear as possible, I can understand your viewpoint.

There you go, making a completely unwarranted assumption. In fact, I’ve never owned a radio station, AM or FM. And I haven’t worked in the business in over 20 years (and considering what consolidation has done to commercial radio since the 1996 Telecom Act, I think I’m better off out of the business!). I’m just sympathetic to AM owners whose signals are losing coverage due to myriad sources of interference that didn’t exist 20 years ago — especially Iniquity Digital Corporation’s utterly useless Hash Disturbance digital signals.

But I’m less worried about that in the long term than about the unregulated use of switching power supplies, especially if they become ubiquitous in lighting applications. Why? Because like the government of the late, unlamented Soviet Union, the ill-conceived “HD” radio system will sooner or later fall of its own dead weight. And that’s true of the FM version as well as the AM version. If and when a critical number of FM’s increase their digital power significantly, self-interference will become a real problem on cheap receivers at the fringes of the protected contours. And if the increase is possible only through the use of different power levels on the two first-adjacent channels, “HD” FM will lose its relative immunity to the effects of multipath—its only real advantage (in some multipath conditions) over analog FM — because that relative immunity is the result of time diversity between the side-channel signals.

But outside of sports and a "right-wing talk" format that will collapse the day Rush Limbaugh decides to retire, what else does AM have to offer compared to FM or streaming?

Good point, but it has nothing to do with the technical problems AM broadcasters face. Contemporary noise sources, and the poor engineering of AM circuits that seem to be little more than an afterthought in many cases, account for the near-total absence of music formats (at least niche ones) from the AM band. (BTW, the local Radio Disney station has finally dropped “HD,” and would probably sound good on an older radio with adequate bandwidth. Unfortunately, all of mine are in storage at the moment.)

As for the “‘right-wing talk’ format that will collapse the day Rush Limbaugh decides to retire,” I hope you’re right about that. But unless we make music formats practical by getting the RF noise under control, the straight-up right-wing bloviating will only be replaced by nominally religious, but actually right-wing political, “Christian teaching” formats like those of both commercial Salem and ostensibly non-commercial outfits like EMF and Family Radio. To me, that’s just an out-of-the-frying-pan-into-the-fire change.

You're getting on me for being arrogant?!?!?!? I haven't owned a two-meter rig in 15 years. I hold an Advanced Class license that I passed in 1972, when I was 17. 90% of my ham operation over the last 40 years has been below 29.7 MHz.

Fair enough. In this case, I made an unwarranted assumption.

And full-carrier AM on the HF bands died out 45-50 years ago, except for a relatively few die-hards.

Yes, but some of those diehards — the ones who use high-quality PA mikes, little if any audio processing and very low modulation levels — produce quality audio that puts most commercial stations to shame.

(A note to Tom Wells: Thanks for your lucid explanation of the problem, Tom!)

 

[KeithE4]

To KeithE4:

You didn't mention that you own an AM station. Given that you have a vested interest in keeping the AM band as clear as possible, I can understand your viewpoint.

There you go, making a completely unwarranted assumption. In fact, I’ve never owned a radio station, AM or FM. And I haven’t worked in the business in over 20 years (and considering what consolidation has done to commercial radio since the 1996 Telecom Act, I think I’m better off out of the business!). I’m just sympathetic to AM owners whose signals are losing coverage due to myriad sources of interference that didn’t exist 20 years ago — especially Iniquity Digital Corporation’s utterly useless Hash Disturbance digital signals.

Sorry about that. I misread your statement and thought you owned a station. My bad. And I agree with you on HD, at least on AM. That flawed system has got to go.

But I’m less worried about that in the long term than about the unregulated use of switching power supplies, especially if they become ubiquitous in lighting applications. Why? Because like the government of the late, unlamented Soviet Union, the ill-conceived “HD” radio system will sooner or later fall of its own dead weight. And that’s true of the FM version as well as the AM version. If and when a critical number of FM’s increase their digital power significantly, self-interference will become a real problem on cheap receivers at the fringes of the protected contours. And if the increase is possible only through the use of different power levels on the two first-adjacent channels, “HD” FM will lose its relative immunity to the effects of multipath—its only real advantage (in some multipath conditions) over analog FM — because that relative immunity is the result of time diversity between the side-channel signals.

I do agree with you in principle, but that horse left the barn decades ago, and it ain't comin' back. Noisemakers that tear up the AM band won't command the FCC's attention until there's an outcry from either the public or a group of congresscritters. Don't hold your breath waiting for either to happen.

But outside of sports and a "right-wing talk" format that will collapse the day Rush Limbaugh decides to retire, what else does AM have to offer compared to FM or streaming?

Good point, but it has nothing to do with the technical problems AM broadcasters face. Contemporary noise sources, and the poor engineering of AM circuits that seem to be little more than an afterthought in many cases, account for the near-total absence of music formats (at least niche ones) from the AM band. (BTW, the local Radio Disney station has finally dropped “HD,” and would probably sound good on an older radio with adequate bandwidth. Unfortunately, all of mine are in storage at the moment.)

As for the “‘right-wing talk’ format that will collapse the day Rush Limbaugh decides to retire,” I hope you’re right about that. But unless we make music formats practical by getting the RF noise under control, the straight-up right-wing bloviating will only be replaced by nominally religious, but actually right-wing political, “Christian teaching” formats like those of both commercial Salem and ostensibly non-commercial outfits like EMF and Family Radio. To me, that’s just an out-of-the-frying-pan-into-the-fire change.

But there is little interest in AM by anyone else. The talk and sports formats are moving to FM. Those AM station owners that can build an FM translator are doing so. Radio Disney has shut some of its AMs down. Mainstream interest in AM is dying out. The big billers (WBBM, WCBS, etc.) are still there, but how long will it last? The blowtorches will eventually simulcast on FM, and those that can't (such as WGN) will be in a world of hurt.

You're getting on me for being arrogant?!?!?!? I haven't owned a two-meter rig in 15 years. I hold an Advanced Class license that I passed in 1972, when I was 17. 90% of my ham operation over the last 40 years has been below 29.7 MHz.

Fair enough. In this case, I made an unwarranted assumption.

Let's agree to quit making assumptions. We've both been guilty of it in this thread. And you know what happens when one assumes... ;D

And full-carrier AM on the HF bands died out 45-50 years ago, except for a relatively few die-hards.

Yes, but some of those diehards — the ones who use high-quality PA mikes, little if any audio processing and very low modulation levels — produce quality audio that puts most commercial stations to shame.

True, but they're limited even more than broadcasters are - to a 6 kHz channel. That's OK for ham use, though. Some of those AM guys do have great-sounding audio. I've also heard some on 75 meters that sound like the average CBer, both in audio and content.

 

[Savage]

Just an aside - who says that Rush Limbaugh and Hannity et al are "right wing?"

Okay, I've lobbed the grenade. Excuse me while I run like hell.

 

[bossbill]

The higher noise levels affecting the AM band helped push the FCC to allow FM translators. They can work wonders for the operator of a rural Class D AM station with terrible nighttime limits. The big boys can use one of their full-power FMs to solve noise problems.

 

[w9wi]

And has anybody tried a DSP circuit in a commercial/mainstream AM radio? I have no idea. I don't own one that has it. Are any are even available other than expensive ham rigs?

For what very little it's worth (grin)...

It's just beginning to come out.

HD Radios use the DSP not only for HD reception but for analog as well. It works VERY WELL. If you're interested in AM listening, it's well worth having a HD radio even if you have no interest in the digital signals.

More recently, it appears a cheap DSP chipset has become available in the Chinese OEM market. A number of inexpensive shortwave portables are coming with this chipset, and DXer reports are that it works pretty well.

(Savage: doesn't Rush himself say he's "right wing"? )