Basics of KNL’s CNHF radio

The KNL CNHF radio system is unique, which can make it difficult for the uninitiated to understand what is actually going on. You can find more technical descriptions of the system on the KNL website. This blog post aims to explain the system’s idea in more mundane terms.

HF radio waves have been useful for a long time as they allow communication over long distances. The KNL system includes an invention that makes HF truly powerful and relevant among modern communication channels: cognitive networking.

How KNL’s radio works

A KNL radio alone is not yet very useful. It needs to find another radio to interact with. Traditionally HF radios have required skilled operators to help them find good frequencies where they can hear each other properly. KNL radios do this automatically, thanks to a small computer inside each radio that can scan the radio frequencies much quicker and more efficiently than a human can. They shout out to the surrounding world which frequencies seem good for them at that time and they wait to hear from other radios that would be available on the same frequencies. When they find a match, they create a connection and can start sending data to each other. If the frequency suddenly becomes useless, the radios find another channel and continue the data transfer from where they left off.

This is what “cognitive” in the KNL radio’s name means. The radios are able to find each other and adapt to circumstances in smart ways, similar to how a human would, but much more efficiently.

Two radios aren’t going to take us very far yet. We want to have several radios ready to talk with each other, so that there is a higher chance that a radio can find a pair at any time. Secondly, we want to get that data available to the human eyes. This means we need some more sophisticated networking.

Connecting KNL’s radios

Often we want the data to appear on a server somewhere. That means the radios need to be connected to some other network, such as the internet. For this we gave each of the radios two roles that they can have simultaneously. When a radio is connected to internet or other such network, it works as a basestation. For example, in maritime use, when the radio is close to shore it can connect to the cellular network – the same your mobile phone uses – and send the data over the internet to the backend, which can again send it further in the same way as if the data was sent from any regular computer. This is done using a secure tunnel to ensure the data is safe.

When the CNHF1 radio is too far from cellular networks to be able to talk directly to the backend, it listens specifically to any radios that might be working as basestations. When it finds one, it can send the data over the HF channels and be sure that it is relayed forward to the final destination. Having more radios in the network makes it more robust: if one basestation stops answering while the message is still not fully sent, the radio can look for another basestation and continue from where it left off. Thus, the larger the network, the more routes there are for sending the messages, and easier it is to get the data to its final destination.

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Read more about the CNHF1 radio

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