I experience crappiness in guitar tone that follows a very rigid weekly pattern. For instance, the rig reliably puts out amazing "mojo" Sunday evenings. Every Monday morning, there is something somewhat displeasing and blatty in the tone that cannot be EQ'd out.
High gain distortion are susceptible due to their nonlinearity. Any RF mixing in there gets modulated down into the audio band. I greatly improved the issue with ferrite beads, but not 100%.
Not all music equipment has good defenses against the ingress of RF. Shunt capacitors on inputs are often omitted, and series inductors are rarely used. The grounding isn't the best: often, unbalanced input and output jacks have ground connections to the audio circuit board, rather than to a Kelvin ground at the power supply. RF can get into the board via that path.
Enjoying all the interference Sunday nights when everyone's home watching TV, but when everyone leaves for work Monday morning, there's less pleasing interference? :)
I'm wasting my breath I know, but if a Transmitter is affecting a non-radio device it can never be the fault of the Transmitter.
As you say, the problem is lack of "Immunity" in your guitar amp, and not a fault in the transmitters around you. Importantly there is nothing which can be done at the Transmitters to cure your problem. Only better design of your music equipment will fix the problem.
Your claim that "High gain distortion are susceptible due to their nonlinearity" is just wrong. Any electronics can be properly shielded by good design. That your fuzz-pedal misbehaves is due to cheap design.
The topic here is spurious emissions, which are a tiny, tiny percentage of actual wanted transmissions. If your guitar amp is effected by spurious emissions, then it would be totally wiped out by any radio transmissions in your neighbourhood.
The FCC has great fun giving out 5- and 6-digit fines. They're pretty reasonable about it too. If it's an honest mistake or misunderstanding, a first time, or you're under some financial hardship no- or readuced-fines are common.
If you willfully continue to violate, especially if you've been warned, huge and or daily fines are common.
...
Equipment is regulated and you can't sell things that break regulations. If fining the retailer isn't effective or possible, they use the financial system against you and threaten the payment processor.
All of these fines are adequate to pay for enforcement.
When it comes down to it, many of the threats which might annoy the public could just as easily be threats to national security with slight tweaks to frequency. With that, there's no problem getting continued support for enforcement all the way from the top.
It sounds like Obama put some really competent people at the FCC. Just look at what happened with net neutrality, the head of the FCC is now one of its big champions.
Politics aside, it's not every day that you get to appreciate what a government agency is doing like this.
The government is staffed by people and the vast majority of it does work well and has real flexibility on a case-by-case basis. What you hear about are the problem cases: the NSA, the FBI, abusive police, mandatory minimums. What you don't hear about is everything else.
The news _should_ be about informing and educating people about the current state of the world, including the parts that are working well. Why does obsessing over crime and inflating the importance of celebrity and politician have to dominate the news?
Because it's what people pay for. Unless a news outlet is publicly-funded (NPR, the BBC), they all eventually face a choice: give the people what they want, or go out of business.
This is the wrong way to think about it. It's not what you pay for because almost nobody is actually making a choice to pay for it.
It's what they think you want. They're all trying to sell what they believe has the broadest appeal which happens to be vapid, emotionally charged shit. The thing is, when everyone is selling the most broadly appealing product, the whole market consumes less.[1]
I personally consume very little because it has such little value to me. There are quite a few like me for various reasons.
I can imagine a public or private entity that goes around and fines people that do not switch off bad equipment and fine the manufacturer (or bar them from doing business in the country).
Ham Radio operators or clubs will often track down rogue radio operators or significant sources of noise, like arcing power lines and report the source to the power company or FCC.
The manufacturer is often nearly impossible to find, and they're not doing business in the country, some enterprising ebay power seller is.
Baby monitors, wireless yard cameras etc are often absolute garbage from an RF point of view, and sold with brand names such as "best for baby". Good luck trying to nail that company.
The FCC's mandate isn't to stop everyone everywhere in the world from producing crap $5 baby monitors that spew noise on the whole spectrum. Their mandate is to keep those crap baby monitors out of the US and off US markets. Which they can do relatively easily; even if the manufacturer is hiding behind seven proxies, twelve shell companies and sourcing from two dozen countries, those baby monitors still had to get into the US at a particular port of entry, had to be sold by someone who had the ability to take payments from and arrange delivery to people in the US, etc., and that's going to point to someone the FCC can happily issue big fines to, discouraging them from continuing to import/sell the devices.
There are literally dozens of sites you can buy cell jammers from, pay with PayPal and get it in the mail a few weeks later. The mail is really not checked for this kind of violation very often.
Who are you going to sue if I order a cell jammer from a China or Hong Kong based company and your own governmental postal service delivers it to me? How about if it's just a crappy or malfunctioning device that leaks and I have no knowledge of it?
It's a very difficult thing to police... almost approaching war on drugs territory.
The fine and jail time apply to the person operating the jammer. By the way, these "dozens of sites" are all too happy to turn over purchase records to law enforcement if asked.
As for "it's a very difficult thing to police", a jammer is a transmitter, one that's powerful enough to drown out the signals it's designed to jam. Turning one on is like turning on a giant flashing billboard saying "ARREST ME" over your head; it's easy to follow the jamming signal back to the source with the right equipment, which, of course, the FCC and similar agencies have plenty of.
> Who are you going to sue if I order a cell jammer from a China or Hong Kong based company and your own governmental postal service delivers it to me?
This can be fixed, however, electronics will cost more when properly designed and filtered. Until interference impacts a lot of people (not just hams and OTA TV viewers) no one will care enough to do anything about it.
Only if they realize it is a problem. I did a short term thing where I was a passenger with someone that was on the road all the time. They had no idea that their Walmartian USB power adapter was blowing out radio reception until I unplugged it.
If the MRI engineer we use is to believed, us leaving the scanner door open by accident led to a very grumpy letter to the MR vendor by the coast guard. 3T so I'm guessing 128ish MHz, I'll let someone else judge if this story is bs.
The Kessler syndrome is about satellites, once you have an overpopulation they collide, smash into smaller bits, causing more collisions, causing more impacts, until its foolish to launch another satellite to replace the damaged ones because it'll get destroyed immediately and merely create more junk that destroys whats already up there, and launching an armored (military) satellite would just result in more bits of armor destroying more satellites, etc.
Likewise the analogy goes that every receiver needs a certain minimal signal to noise ratio to operate, to demodulate correctly with an acceptable bit error rate. Well, if the noise level goes up your only option is to increase transmitter power level which eats battery and ruins the environment and makes your radio link work, but you just increased the noise level for all the OTHER systems nearby which have to increase their power levels until your system doesn't work, rinse and repeat until nothing works.
A real world historical example is the social media like, CB radio boom of the late 70s. I realize not too many people here are old enough to remember that. But a system that worked well for a modest number of users at a legal and clean 5 watts of transmitter power, suddenly had way too high a density of users, all running illegal noisy 100 watt amplifiers because they wanted to be heard over other illegal noisy 100 watt amplifier users, etc. Eventually the system completely collapsed and all the users left because it didn't work for anyone anymore and CB is in the dustbin of history, pretty much.
In the long run to an end user it would look like in the countryside your bluetooth or wifi or anything else that uses radio will have a very long lasting battery and great range and be pretty reliable although the hardware will be much more expensive than it is now to try and work in the city, but in the city the battery life drops by a significant fraction, everything is slow and unreliable, range drops from across a large room to just a couple inches for bluetooth if it works at all, wifi is unusable in some areas that have hundreds of access points interfering with each other, etc. Some services would simply stop working in a very high noise environment due to high difficulty of increasing transmitter power. No more GPS, broadcast radio, possibly cell phone service, probably no more police/fire radios. The concept of a police car no longer having a usable reliable radio is weird.
We're nowhere near "extreme" levels of noise yet, thankfully. Extreme levels of noise will – just like audio noise – cancel out any signal you're trying to emit. That's a real problem because everything communicates by radio these days.
But even though we're nowhere near extreme levels, this still causes problems in some areas of the world. I don't remember the specifics, but some train-related communications system where I live uses a part of the spectrum that's apparently very busy. This means the train drivers often have to rely on the civilian cell phone system to communicate, which in an emergency will be absolutely swamped and really hard to use.
Going along with the metaphor of the submission: sure, in the same way you can plant a solar cell on your roof and get "free energy" from the light pollution during the night if you live in a city.
Or, literally, the energy is way too low to benefit from it. Sure, the TV might blanket space with a few watts of interference, but going by the law of quadratic decay that's not worth much at distance.
All this noise does is prevent observation of low-energy signals. It does not contribute to a high-energy signal itself. (Goes for both light pollution and RF noise.)
Edit: unless, of course, you mean we can "harvest" this free energy by making our appliances conform to regulations, in which case it's an obvious yes.
I built a Tesla coil in middle school. I was able to get a 3' long fluorescent bulb to light up at distances of over 10' away. I also knocked out radio and TV reception for the entire block when it was on. Oops.
Yes, which raises one possible way of fighting it: Make electronics manufacturers adhere to power efficiency ratings. The moment they have to care about how power efficient their gear is, they'll look at everywhere power's being wasted by, I don't know, being broadcast into the air for absolutely no good reason.
That's probably not going to be effective. Look at devices with cheap universal motors and the like. They spew out tons of noise and a lot of them have a filter on the input to cut down on noise but as far as decreasing wasted power, the RF noise is a tiny drop in the bucket compared to the total power of whatever power tool or vacuum we're talking about. Also, the filter that they put on the input to try to combat this doesn't increase the efficiency of the device. If anything, I'd be afraid that there would be design changes to decrease the thermal losses of a device even if it increased the noise it put out.
Funny, but incorrect. This mostly has to do with spurious RF noise generated by badly engineered devices like power supplies or manual light dimmer switches - things that aren't designed to communicate. Manufacturers are supposed to test for these sorts of emissions, but frequently don't.
Meaning you're claiming in a cities NYC & DC that the NSA doesn't to full spectrum dumps, right? Or that they would have not looked into statistically unusual high amounts of background noise?
If the NSA does this, they'd have the info. If they don't, I'd be curious why; meaning legal, physical limits, etc.
This has nothing to do with the NSA, and the NSA has no interest in RF noise. The noise isn't some encrypted electronic communication. It's electromagnetic noise as a byproduct of poorly designed electronic products. It's like if in a chemistry lecture if all the students started humming, it would become difficult to hear the lecture. So there is no connection to the NSA.
How can this be a real problem with exponential signal loss over distance? Sure, two devices in close proximity may interfere with each other. But that is in no way a "noise floor issue which will render certain frequencies unusable."
Signal strength does not decay exponentially, rather as distance^-3 for a dipole[1]. Most noise sources are probably well approximated by a dipole antenna[2]. Some fancy modern modulation scheme with extremely dense encoding of information might suffer stronger decay, but the article is about simple sources of noise, not about modern modulation schemes.
This is my intuition as well, because at a distance r around the source you have a sphere, and the area of the sphere will relate to the radius r as r^-2.
That said, the equation linked in the comment does indeed contain an r^-3 factor. I don't know if it's cancelled out by something else – my physics game isn't strong enough.
The expressions for the field include terms of different powers of r. At large distances (compared to the wavelength) from the transmitting antenna, only the r^-1 terms (which dies off with r more slowly than the others) remain with any appreciable strength. This is called the "far-field". The power per cross-sectional area is proportional to E·B (or, equivalently, to E^2 or to B^2), and therefore goes as r^-2.
The recent problem isn't the decay rate of RF but the cost of noise attenuation per dollar.
A legal switching power supply in a PC might knock out all AM radio reception on the same desktop. That's because the mfgr installed $5 worth of inductors and bypass capacitors in the power supply input section. So maybe 500 watts output, 4.999 watts of noise gets turned into heat by those interference filters, and 0.001 watts messed up the AM radio on the same desktop.
(edited to add BTW if you think your cheap switching power supply is 99% efficient I have a bridge to sell you... the actual numbers are worse)
The problem is those inductors and capacitors and ferrite cores are $5 of "lost" profit in China, and technically the power supply works with them replaced by pieces of copper wire. So the same 500 watts output, and 5 watts of noise broadcast into the neighborhood. Well, at least its not turned into heat inside the chassis, LOL. The problem is a 5 watt transmitter is going to knock out AM radio for some city blocks in every direction.
In the 30s your average house had like one piece of electronics, probably an old console radio. But now houses are full of electronic junk from China so you're battling pretty much everyone who wants to get the lowest priced XYZ from walmart. Like some forms of pollution, RF interference is virtually impossible to clean up and the biggest violators have a significant payoff, higher profits at the factory and cheaper products on the shelf, or some continuum along that spectrum anyway.
A good analogy would be trying to organic garden in an urban environment surrounded by pollution and pesticide spraying. You might not be dumping god knows what into your dirt, but your neighbors simply don't care and are constantly spraying or dumping who knows what, and you share the environment so even if per UDSA your dirt is legally organic because YOU didn't mess it up, you still know its a regular toxic brew in there because of your neighbors ...
I have no direct experience with power supplies radiating, except to note that switching frequencies are up significantly, from 20khz twenty years ago to 500khz to 2MHZ today. The AM band is something like 700khz to 1.4MHZ.
Higher switching frequencies and the push for higher efficiency[1] also means very fast switch times, on the order of 20-100ns. High speed signals like that contain very strong harmonics which will leak out.
[1] Old guy mentioned to me what you care about is not the efficiency, but the inefficiency. Because that's directly related to heat. Going tom 90% efficient to 95% efficient, who cares! Except you reduced the amount of heat you need to dissipate by half from 10% to 5%.
Couple of things, there are just more and more devices that have high frequency electronics. So increasingly we're surrounded by a sea of radiators.
A problem with all transmitters is they produce out of band signals. Mostly harmonics, but also lesser amounts of other frequencies. And another issue is that receivers only have limited ability to reject out of band signals. A strong out of band signal will reduce your receivers sensitivity. (Difficulty, out of band rejection comes at the expense of ultimate sensitivity, pick your poison)
The problem then is that the amount of energy needed to raise the noise floor is tiny, minuscule. And we have all these devices that all add a tiny amount each, which then adds up to something. If you raise the noise floor a few db it matters a lot, because following reason.
Consider this, if you double the distance from the transmitter, the signal strength drops by ~6db. So if interference reduces your receivers sensitivity from -120db to -114db it cuts the effective range in _half_[1].
[1] It's not quite half because in the real world you have air, trees, and buildings in the way which means your signal drops off faster than the inverse square. Instead the exponent is more like 2.5(outside) to 3.5(inside)
I think that's a tautology. I'm not sure what "overall effect is a push" means... Is "incidental noise" the dominant factor in the overall noise floor?
Maybe you could call this another kind of "global warming". Any existing historical data readily available?
Is historical data necessary when you can just compare urban to suburban to rural areas?
There's clearly a correlation to population (and thus noisy electronics) density. I've tried listening to the HF ham radio bands from my downtown SF apartment with very little success.
The problem is if you are trying to receive a signal from far away and something in your house or your neighbors house is polluting the band. The interfering signal can be stronger than the desired signal.
Gee, I wonder if it has anything to do with cell phones, and in particular, the high bandwidth data consumption of smart phones.
Look toward a city skyline at night. Or even a small town. You'll see a blended haze of light reaching up into the sky. Probably a similar deal with the general radio spectrum emissions, now that everyone's carrying the equivalent of pocket RF flash lights, and walking in proximity to the RF street lamps that cell phone towers have become.
Cell phones are running several receivers at the same time they're transmitting. The Bluetooth, GPS, WiFi, and GSM receivers all have to receive cleanly while the Bluetooth, WiFi, and GSM transmitters are transmitting. It's amazing that this works. Spurious RF noise from any of those transmitters would interfere with the receivers only a few millimeters away. So cell phone designers have to put effort into getting RF isolation right.
Computers were once big RF emitters, but the FCC cracked down on that successfully in the 1980s. In the early days of personal computing, a Radio Shack TRS-80 and a Milton Bradley Big Trak would both crash if close. In recent years, most computers got radio receivers for at least WiFi, and thus had to be built well enough not to knock out their own receivers.
Analog TV sets tended to emit loudly at the local oscillator frequency. The UK used to drive around with "television detector" vans to find people who didn't pay their TV tax, which funds the BBC. But tuners quieted down years ago, as they became tiny RF-tight sealed units.
The worst behavior comes from switching power supplies, especially for lighting. The cost pressure is very high. They don't receive, so they have no receiver to protect. Another big source of noise is leaky cable TV systems. Again, since they don't receive, they aren't affected by their own leakage. The cable industry has successfully lobbied to escape tight restrictions on cable system leakage. Those two sources are probably the source of most problems.
Low-cost spectrum analyzers are available, and some are laptop peripherals.[1] There are ones as cheap as $69 on eBay, but the consensus in EDN is that you have to pay a few hundred dollars to get something that produces useful measurements. People who install and maintain WiFi networks in large buildings usually have one. Then you can find what's blithering all over the spectrum.
> Analog TV sets tended to emit loudly at the local oscillator frequency. The UK used to drive around with "television detector" vans to find people who didn't pay their TV tax, which funds the BBC. But tuners quieted down years ago, as they became tiny RF-tight sealed units.
CRTs used to emit the picture on their screen well enough you could receive it over a nontrivial distance. This is called Van Eck phreaking.
OTOH, being able to receive a signal and being able to nail down where it's coming from and who's broadcasting it are two very different things, and the location part is substantially harder. Using the Van Eck technique, or any other, to crack down on people not paying the BBC license fee would have cost more than the fee was worth. Psychological ploys with faked-up vans, however, are a lot cheaper, and can be fairly effective.
TV detector vans, despite being theoretically possible to build, are a myth and just propaganda spread by the TV license collection agency. At most they drove around in vans with some random gear in it as PR stunt.
>The Bluetooth, GPS, WiFi, and GSM receivers all have to receive cleanly while the Bluetooth, WiFi, and GSM transmitters are transmitting. It's amazing that this works.
Um, yeah, about that, that would be really nice if it were true. Maybe sometimes for some hardware in some situations. For a 1st gen motorola droid X I can personally guarantee when the wifi gets unusually frisky the bluetooth drops out. Very annoying when listening to music on a BT earpiece. A hardwired headphone never drops out, but a main marketing point of USB-C is to get rid of headphone jacks because they work well and they're too cheap to profit off.
The cable leakage thing was true in the 80s, but the FCC wisely put pretty low transmit level limits on all the two-way gear (settop boxes, cablemodems, cable phone modems). To make a long story short if signals are getting out, interference is getting in and is measurable and is likely causing an upload/upstream problem. If you think microwatts of output power from a cracked cable is annoying to a fm radio listener, imagine a "miles long" cable with a crack acting like an antenna across the street from a 50 kilowatt am transmitter and consider its effect on modem upstream speeds. Problems will happen, but it'll get fixed pretty fast, unlike the 80s or something. Maybe a decade ago the journalists made a sport of complaining about digital phone service being unable to dial 911 and that was the end of unrepaired cable leakage problems.
> when the wifi gets unusually frisky the bluetooth drops out
Oh so that is why my bluetooth audio gets choppy when I walk past the wifi access point in the hallway? I've never even thought about that before other than been annoyed by it.
How utterly inconvenient that they occupy the exact same frequencies. I should probably get a 5 GHz wifi access point...
My issue is money and space. I'd like to cram it into the same tiny little box that already houses the fibre-to-ethernet converter as well as the router. I'm also not sure if it would penetrate the walls and reach all rooms.
The major source of RFI from switching power supplies is not the switching frequency or its harmonics. It is a parasitic LC oscillator formed by the capacitance across the switching transistor, and the parasitic inductance between the capacitor and its DC voltage source. Every time the power supply transistor switches, that parasitic LC tank is struck and rings like a bell. 1-10 MHz is a common range for this ringing in a big supply (10's of kW and up). As the components get smaller, the first parasitic ringing frequency goes up, too.
I'm a radio ham. No, it has little-to-nothing to do with smartphones, which are incredibly tightly regulated and operate in very tightly defined bands of the EM spectrum.
My guess (and it is only a guess) is that the problem is mostly from unregulated imported electronics that emit all kinds of broadband RF noise as a consequence of being made cheaply.
Continuing your analogy, cell phones are like supermarket barcode scanners: weak and clearly red. It does not really matter how many of them you cram into a room, you can still send morse code with a green laser.
All devices have small daylight lamp attached to them, the power of which is rather strictly regulated (IEC-61000, if anyone is interested). If you cram a lot of them into a room, morse coding with that green laser becomes difficult. You could increase power/brightness of the laser and call the problem solved. But then try to measure brightness of your lighting fixtures - becomes quite difficult.
So no, proliferation of cell phones is only a problem for cell phones (one of the reasons for migrations 2G -> 3G -> 4G). The real problem are other devices transmitting in cell phone spectra effectively DDoS'ing them.
High gain distortion are susceptible due to their nonlinearity. Any RF mixing in there gets modulated down into the audio band. I greatly improved the issue with ferrite beads, but not 100%.
Not all music equipment has good defenses against the ingress of RF. Shunt capacitors on inputs are often omitted, and series inductors are rarely used. The grounding isn't the best: often, unbalanced input and output jacks have ground connections to the audio circuit board, rather than to a Kelvin ground at the power supply. RF can get into the board via that path.