Is electromagnetic noise an obstacle to the Internet of things?
A lot of copies are now breaking down regarding possible ways to implement the Internet of things. Yes, and the realizability itself causes a lot of questions and disputes. However, judging by the efforts of manufacturers, the Internet of things is more likely to be than not to be. But here there is another problem of a technical nature: the Internet of things is a priori a distributed wireless network, which can be strongly and unpredictably affected by electromagnetic pollution created by countless devices and wires.
The urban environment is filled with sources of electromagnetic waves. Devices, gadgets, even wires have their own electromagnetic fields, the parameters of which depend on the operating modes of the devices and the load level. Superimposed on each other, they create in our homes and on the streets an unpredictable radiomagnetic cacophony.
Powerful transformers, power lines, public transport contact wire networks can create strong interference in our radios and televisions, and worsen the quality of mobile communications. It happens that even the inclusion of a household appliance leads to interference on the TV screen.
In the equipment around us, you can find relays, connectors and electric motors that create electromagnetic noise. Even car engines contribute to creating a constant electromagnetic background in cities. Processors and displays of numerous gadgets emit weak waves. High-voltage "ballast" of neon signs "phonite" in a wide range of the spectrum. Machine tools and devices used in production, elevators, welding machines, relays, generators, even simple light switches - all this creates a “living”, pulsating medium from waves of various frequencies.
The problems associated with electromagnetic pollution can be divided into four categories:
- The increase in the cost of deploying wireless systems, as well as reducing the duration of mobile devices.
- Numerous interference in various spectral bands.
- The level of electromagnetic pollution is practically not regulated by law. The more noisy the spectrum, the wider the transmission needed to transmit the declared amount of data per unit time. Therefore, many wireless devices in fact do not provide the declared speeds.
- Finding sources of electromagnetic pollution is an expensive pleasure. And eliminating its causes is extremely difficult.
The Internet of things will make the situation even worse. Much worse. There will be countless devices connecting to the Internet wirelessly: door locks, lighting, switches, household appliances, our cars, and perhaps even our bodies. Each of these devices is a potential source of electromagnetic pollution. Technically, there are a large number of ways to solve this problem, but this implies the complexity of device designs and their cost.
Information on Russia could not be found, and in the United States a fundamental study of electromagnetic pollution was last conducted in the 1970s, when the Institute for Telecommunication Sciences (ITS) published a large-scale study of the US radio spectrum.
Only in 1927, with the invention of the method of suppressing radio waves, it became possible to listen to the radio in the car simultaneously with the engine running. By the end of the 1930s, 20% of all cars in the United States had integrated radio systems.
As part of a study at ITS in the 60-70s. large-scale measurements of emissions emitted by vehicles were carried out. It was found that in many models the noise suppression was so imperfect that electromagnetic noise was recorded several blocks from its source.
Today, there is a radio in every car, and the problem with interference has long been resolved. In the 1960s, more “quiet” alternators appeared; later, injectors replaced carburetors. Electronic switches replaced "noisy" relays. So we use smartphones and radio without problems while sitting in the cabin.
Similar processes have affected our homes and jobs. A simple incandescent lamp, which used to produce a large amount of electromagnetic noise, has now become much "quieter." Wireless modules in gadgets have also become more sophisticated over time.
However, the problem of electromagnetic noise is becoming increasingly important. Despite the fact that most devices began to create less noise, the quantity of equipment itself increased significantly.
Modern gadgets are especially sensitive to electromagnetic pollution. Mobile devices should operate with minimal power consumption while maintaining maximum functionality. This means that even a small level of noise can significantly affect the quality of communication.
Unwanted radiation can be intentionally embedded in the design of the device itself. For example, in a microwave, microwave waves not only heat food, but also radiate into the surrounding space, significantly increasing the level of electromagnetic pollution. Noise can occur due to a partial malfunction of the device, for example, as a result of microdamage to the grounding shield in the insulation of a high voltage system.
Such problems lead to spontaneous bursts of radiation, suddenly, with unpredictable frequencies and in unknown places. The graph shows some patterns of electromagnetic pollution that are typical for different urban locations: The
inverse dependence of the noise level on frequency is due to the fact that switching power supplies are noisier the lower the frequency.
Take, for example, transmission line radiation due to damaged insulation. In the United States, where the network frequency is 60 Hz, electromagnetic noise will occur either at a frequency of 60 Hz (every 16.7 ms) or 120 Hz (every 8.3 ms). This is due to the fact that a “noise” pulse occurs at the maximum negative or positive voltage (60 Hz) or at each of them (120 Hz). This gives reason to argue that noise is generated either by the transmission line or the device connected to it. The most common cause of electromagnetic noise below 1 GHz is the mains itself.
Another example of a noise source with a distinctive “pattern” is microwave ovens. Household microwave ovens can emit 2.4 GHz frequency noise. All kinds of low-power devices are actively using this part of the spectrum: receivers of wireless “mice”, cordless landline telephones and Wi-Fi. Many other electrical appliances, including chargers for smartphones, tablets and laptops, have switching power supplies that produce hundreds of kilohertz noises in the harmonics of the power switching frequency.
Let's assume that electromagnetic noise degrades signal reception by a smartphone. How to find out what is the cause? Without special appliances - no way. You simply write it off to anything, even to a bad provider, but not to electromagnetic pollution in this place.
Usually, it is impossible to predict how modern radio transmitters with their exotic digital modulation schemes will work in the event of a defect or breakdown. But older systems are much more predictable. In addition, automatic error correction systems can make the effect of interference completely invisible to the user. In fact, the only sign of interference today may be a faster discharge of your smartphone’s battery.
To begin to solve the problem, you need to collect a huge array of statistics. We must determine where electromagnetic noise occurs most often, at what frequencies, what is the source. We need examples from different regions with the obligatory indication of what kind of equipment was used for measurements, what were the weather conditions, landscape, remoteness from buildings, and much more.
If such a relevant database existed for different countries, then, theoretically, many standards existing in a number of industries could be reviewed. But this, as you know, is associated with high costs for many companies. In addition, it will be very difficult to find a balance between the cost and effectiveness of such changes.
Definitely, it is necessary to reconsider the approach of state regulators in this area. Today, we are only concerned with the effect of radiation from various radio transmitters, including mobile phones and the infrastructure of mobile operators. And electromagnetic noise is ignored by everyone, although it could potentially be much more harmful.
State regulators must resolve this issue. At least from the point of view of deterioration of communication quality with increasing load on the same part of the frequency spectrum. We are already heavily dependent on wireless communication systems, and in the future this dependence will grow and expand. Therefore, engineers will have to create new devices based on the conditions of high electromagnetic pollution.
The problem will only worsen with the advent of an increasing number of devices that use more and more spectrum frequencies. There are no universal technologies or tricks to suppress electromagnetic noise. After all, there can be many reasons for its occurrence. It is possible that it is precisely because of electromagnetic pollution that many Internet of Things users will be disappointed in this technology, creating the first products undeservedly bad reputation.