Summary:
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- KNL’s automatic link establishment (ALE) system sets up HF radio links in just 0.5 seconds without requiring GPS or time synchronisation, outperforming traditional 2G, 3G, and 4G ALE technologies.
- The CNHF system can listen to over 4,000 channels (HF/VHF) simultaneously, enabling fast, interference-free link establishment even in jammed or GPS-denied environments.
- Dual-frequency negotiation allows data and acknowledgments to travel on separate channels, improving reliability in asymmetrical interference conditions.
- Features like robust mode and multihop enhance resilience by allowing operation in poor signal conditions and automatic relaying when direct links are unavailable.
- Multicast and broadcast capabilities enable message delivery even to radios in silence mode, making the system highly adaptable for tactical communication scenarios.
Automatic link establishment, or ALE for short, has traditionally been seen as a bottleneck in HF communication. Each generation has brought challenges as HF technology has evolved through various stages – from 2G to 3G and 4G ALE. At KNL, we have developed an advanced solution for automatic link establishment that overcomes the typical problems of HF ALE radios.
With KNL, automatic link establishment is not only fast – 0.5 seconds – but also secure and dependable even in jammed conditions. How is this achieved?
Continue reading to find out why KNL’s automatic link establishment is much better than the automatic link establishment in 4G and 3G ALE HF radios!
Read also: KNL radios deliver on promise of HF renaissance
What is automatic link establishment?
- Automatic link establishment, or ALE, is a technology used in HF radio communications to set up communication links automatically. ALE incorporates various mechanisms to synchronise the transmitter and the receiver on the same functional and free frequency.
- Using an ALE radio simplifies the process of finding the best available frequency for communication.
- KNL’s cognitive networked, software-defined wide-band HF radios utilise advanced automatic link establishment technology, offering significant improvements over traditional ALE HF radios.
- KNL’s ALE operates extremely quickly, within 500 milliseconds, and enables asynchronous link establishment and communication, which is crucial in GPS-denied or other congested environments.
KNL’s solution to automatic link establishment improves the efficiency and reliability of HF communication
Automatic link establishment (ALE) has typically been seen as a bottleneck in HF communication due to the high volume of transmissions in the HF band, making it difficult to predict which frequencies are actually available. The propagation of HF signals varies throughout the day as it is influenced by the sun, affecting what time of day selected frequencies reach certain destinations.
Read more: Basics of HF Technology
What sets KNL apart from previous ALE HF radios is our advanced technology, which allows our radios to listen to thousands of frequencies simultaneously. We are redefining the HF market, allowing users to efficiently and automatically use the whole HF spectrum through cognitive sensing for voice and data.
Our CNHF Manpack radio automatically receives over 4000 calling channels simultaneously, while the original CNHF1 Radio is designed to listen to over 2500 calling channels. This capability enables automatic link establishment on any of these frequencies at any given moment, providing several advantages.
Firstly, there is no need for time synchronisation, effectively eliminating the dependency on GPS or other time sources, which 3G ALE radios often rely on for their automatic link capabilities. Secondly, with thousands of available frequencies, it is highly unlikely that all 4000 channels would be jammed or occupied simultaneously, making it very likely to find an interference-free frequency.
High-performance ALE radios: Dedicated frequencies for data and acknowledgments
Another significant advantage unique to KNL’s systems, which is not found in competing HF ALE radios, is the ability to negotiate frequencies in both directions during automatic link establishment. This means data can be sent at one frequency while acknowledgments (ACKs) are sent at another. This dual-frequency approach allows for bypassing local interference at one end, ensuring that messages are reliably and securely delivered. Using KNL’s radios you get a more dependable connection, especially in beyond-line-of-sight communications.
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The KNL radio used with a tablet
Evolving automatic link establishment technologies: from 2G to 4G ALE
Technologies for automatic link establishment have been developed since the 1970s, evolving through various stages from 2G and 3G ALE to 4G ALE. How do KNL’s solutions stand out? The answer lies within the history of ALE technology.
The first widely adopted version was 2G ALE, which had significant limitations due to its few available frequencies, slow connection times, and overall unreliability. It took a long time to establish connections. In the late 1990s, 3G ALE was introduced, offering faster and more robust connections. However, it required precise time synchronisation, meaning all radios in the network needed to be synchronised because they switched frequencies simultaneously. This led to an unforeseen problem: GPS jamming.
Practically all 3G ALE radios use GPS for time synchronisation, so when GPS signals are jammed, the radios fall out of sync, causing automatic link failures as radios switch frequencies at different times.
Enhancing capabilities: 4G ALE vs. KNL’s automatic link establishment
To address these issues, 4G ALE radios have been developed with the capability to listen to multiple frequencies simultaneously and initiate automatic links without requiring time synchronisation. However, compared to KNL’s advanced system, 4G ALE still has a relatively limited number of frequencies it can utilise.
By utilising spread spectrum technology and cognitive networking, KNL’s system prevents the entire network from being incapacitated. All connection calls are radio-specific. In contrast, 2G ALE HF radios are easy to jam because they start transmitting with a very long, uniform call that is the same for every radio. If the call is exposed to jamming, all radios will catch it and wait for the message, making it easy to incapacitate the network with minimal transmission power.
Additionally, the so-called robust mode enhances the anti-jamming capabilities of KNL’s radios. The robust mode is an integral part of our radio systems, meaning the system can seamlessly switch from one mode to another without any user intervention. Next, let’s focus on examining the benefits that robust mode brings to automatic link establishment.
The robust mode in KNL radios means that they can operate with limited performance even in very difficult conditions, such as when signal propagation is very poor, or there is a lot of interference.
KNL radios can operate even in very difficult conditions
Automatic links supported with KNL’s robust mode: reliable performance even in harsh conditions
Military and defence communication occurs in increasingly demanding conditions, requiring HF radios to have more versatile anti-jamming capabilities. How have these features been developed in KNL’s radios?
KNL radios feature a significantly more advanced modem compared to traditional 2G or 3G ALE HF radios, allowing our radios to operate with a much lower signal-to-noise ratio.
In practice, by operating our radios, you can trade data transfer capacity for robustness: by lowering the data transfer speed, you gain robustness, meaning better interference tolerance and reliability. With fewer bits per unit of time, a lower signal-to-noise ratio is sufficient, allowing capacity to be traded for robustness. You can be sure that your message gets through regardless of the conditions.
The HF Networking Features of KNL’s radios:
- Multihop mode: automatic multihop functionality over one relaying node of HF if direct connection is unavailable.
- Robust mode: robust data transmission capability for severely disturbed poor HF channels. Required also for interoperability with legacy HF radios using CNHF Evolve upgrade device.
Read more about high-noise challenges in HF communications
Our software-defined radio offers different HF networking features: multihop and robust modes. Both are integral parts of the radio system, allowing seamless switching between modes without user intervention.
Strengthening automatic link capabilities through multicast and broadcast features
The multicast and broadcast features of KNL’s radios enable use cases that can be challenging for many 3G ALE HF radios.
Multicast allows one transmitter to send a signal to multiple selected receivers. The multicast and broadcast feature enables one transmitter to send a signal to multiple or all receivers, even in case when the receivers are in radio silence mode.
For example, in situations where one side is maintaining radio silence for any reason and cannot respond, it would typically be impossible to get a message through with traditional ALE HF radios. However, with KNL’s multicast and broadcast feature, you can still send a message to everyone in the network.
Get connected and stay updated on the progress of Cognitive Networked HF radio
We at KNL aim to be at the forefront of providing modern, efficient, reliable, and secure solutions for the needs of military and defence professionals around the globe. To learn more about cognitive and software-defined radio technology and its benefits, subscribe to our newsletter.