Shortly before access to BBC News was banned in Russia a few days ago, the BBC announced that it would resume broadcasting BBC World Service on shortwave radio for four hours a day. She said this was to ensure that people in parts of Russia and Ukraine could access her news service.
In a world where cell phones are almost ubiquitous, the use of radio technology in the early 20th century might seem unusual. But this makes sense for a number of practical reasons.
Shortwave radio is the old alternative to what many people might remember as an analog “AM” radio, running on low-frequency radio waves to deliver audio services. Shortwave radio is much simpler than modern digital television or telecommunications services: receivers are widely available (or can be built from electrical parts), and they operate over long distances.
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Traditional television and radio broadcasting is fundamentally different from modern Internet-based services. Like Freeview TV that is received over an antenna, traditional broadcasting services don’t require you to send anything to be able to receive the service. It is transmitted once, and anyone with a receiver can listen or watch.
When someone uses a shortwave radio receiver, there is no lasting trace of their use. This makes it difficult for the occupying power to find those who listen to foreign (possibly banned) media.
Conversely, when you are surfing the Internet or using a mobile application, your device requests the content you wish to receive, and it is sent directly to your phone. This two-way communication means that when you are surfing the Internet, different entities such as your Internet provider can see that you have visited certain websites.
Internet-based services can also become overburdened, either as a result of high demand, or due to malicious attacks that flood the service with requests, with the goal of making it unavailable.
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There are a number of other technical reasons why shortwave radio is very useful in crisis situations. Because it uses low transmission frequencies, signals can travel much farther than TV or mobile phone signals – thousands of kilometres, rather than kilometers or tens of kilometres.
This means that the BBC can broadcast from abroad to the conflict zone without the need for a local physical infrastructure. And because lower frequencies are used, signals are better spread across buildings and the environment. If you have ever encountered a weak mobile phone signal in the middle of an old building, you have faced the challenges of wireless propagation. Low-frequency signals reach buildings and basements better, even when sent from afar, which can be beneficial for people sheltering.
Shortwave radio receivers can be very energy efficient. You can run a portable radio for days on batteries, and many cars have a shortwave-capable radio, which can be powered from the car’s battery. There are even wind-powered or solar-powered shortwave radio receivers.
Although mobile phones can be charged from power banks, solar panels or car chargers, they require a lot of infrastructure, such as radio poles, power grid connections, and optical fibers. Any of these may fail, or be deliberately targeted, disrupting some or all of the network. If the local mast goes out of power, the grid in that area will go down. If core network locations are damaged or power outages, the entire network will become unavailable.
Moreover, cell phones and other digital radio technologies are designed to use low transmission power to make it more cost-effective for mobile operators to reuse the same frequencies in different areas. This means that network operators reduce signal strength where possible.
This makes it practical for almost anyone to attempt to jam and block access to mobile networks, using portable jammers (which are generally illegal to possess or use). Jamming shortwave signals is more difficult, as it generally requires a network of large, high-powered transmitters spread across the country, operating on the same frequency.
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In the current war, the shift towards traditional wireless technology is not only seen in the context of news broadcasting. There are numerous reports of Russian military units using unencrypted analog radios, or “walkie-talkies,” to communicate on the battlefield.
In hostile environments, simpler and sometimes older technologies are more readily available, and can provide a more reliable communications channel than more complex modern alternatives.