An Introduction to Troposcatter: Revolutionising Military Communication

Communication is critical in military operations, where success can hinge on the ability to communicate quickly and reliably over long distances. However, traditional communication methods like satellite and line-of-sight systems have limitations that can make communication difficult or impossible in certain situations, particularly in remote and rugged terrain, and in satellite-denied environments.

Troposcatter communication offers a solution to these limitations by using the lower part of the Earth’s atmosphere to scatter radio signals, allowing for communication over long distances, up to 250km, without requiring line-of-sight. In this article, we will explore the basics of troposcatter communication and why it has become an important technology in military operations. Specifically, we will cover the following points:

• What is troposcatter communication and how does it work?
• Advantages of troposcatter communication over traditional methods in military operations
• Limitations and challenges of troposcatter communication in military contexts
• Real-world applications of troposcatter communication in military operations

As military operations continue to rely on communication technology for everything from command and control to situational awareness and intelligence gathering, troposcatter communication offers a promising solution to some of the limitations of traditional methods. By the end of this post, you will have a better understanding of what troposcatter communication is and how it can be used to revolutionize military communication.

What is Troposcatter Communication and How Does it Work?

Troposcatter communication is a method of transmitting radio signals over long distances by using the troposphere to scatter the signals, a small proportion of which is received by the distant station. This technology is becoming increasingly important in military operations, where reliable communication is crucial for success.

The troposphere is the lowest layer of Earth’s atmosphere, up to about 13km. Most of the mass (about 75-80%) of the atmosphere is in the troposphere. Most types of clouds are found in the troposphere, and almost all weather occurs within this layer.

Unlike satellite communication, which relies on a direct line-of-sight to the satellite in orbit, troposcatter communication scatters RF energy or “blobs” of irregularities within the troposphere (at a very low angle). The signal is then scattered back down to Earth, where it can be received by another system.

One of the advantages of troposcatter communication is that it does not require a direct line-of-sight between the transmitting and receiving antennas. This makes it ideal for use in remote and rugged terrain where traditional Line of Site communication methods will not work.

Compared to other forms of communication such as satellite and line-of-sight systems, troposcatter communication has some unique advantages. For example, it is less susceptible to weather interference, making it more reliable in adverse conditions. Additionally, troposcatter communication can provide a significantly higher bandwidth than traditional satellite and line-of-sight systems.

However, there are also some limitations to troposcatter communication. The technology is limited to approximately 250km using deployable systems so is not suitable for inter theatre links,

Not all links are viable. The planning tool will quickly identify a viable link for the chosen deployable systems and will optimise the locations to maximise throughput. Siting is critical, 100M can make the difference between an adequate link and an outstanding, high bandwidth link.

The troposphere is dependent on temperature, pressure and humidity. This creates variation in the troposphere throughout the day and is more pronounced over the seasons. This variation is far less pronounced that the variations with the ionosphere, but it does mean that the system performs better in the summer than the winter.

Used within these limitations, troposcatter communication is becoming a critical technology in military operations, where reliable communication can mean the difference between success and failure. As we continue to rely on communication technology for everything from situational awareness to intelligence gathering, troposcatter communication offers a promising solution to some of the limitations of traditional communication methods.

Advantages of Troposcatter Communication in Military Operations

Troposcatter communication has become a popular choice for military communication systems due to several advantages over other forms of communication. Here are some of the key advantages of troposcatter communication in military operations:

High-bandwidth communication:

Troposcatter communication can provide higher data rates than traditional line-of-sight and satellite communication systems. Troposcatter communication uses a wider frequency band, complex phase and amplitude modulated waveforms, and multiple channels, enabling it to simultaneously transmit and receive more data (up to 210 Mbps). This makes it ideal for big data applications, and multiple VTC and Streaming ISR feeds.

Low Latency

In military communications, it is essential to understand the range and latency of different types of links to ensure efficient and effective data transfer. A Tropo link typically has a range between 50-250 km, with a latency of between 9-20mS. In contrast, satellite systems have a much greater round trip of over 70,000 km, resulting in a typical latency of between 300-800 mS.

When utilising a connection-oriented protocol such as TCP, the link’s latency can directly affect the data throughput, with limitations at higher latencies. TCP uses a series of negotiations and controls to transfer data, and one such control is the TCP acknowledgement packet used to confirm delivery after an agreed-upon “window” of data has been sent. Once that amount of data has been sent, the sending end will not send more data until the last set of sent data is acknowledged. Therefore, the maximum window size has to be achieved before acknowledging the received packets and moving on to send more data.

It is important to note that throughput is inversely proportional to latency. Therefore, Tropo data throughput can be calculated to be 30 to 40 times greater for an identical bandwidth link. With significantly higher bandwidths available with Tropo, the real data rate can be hundreds of times greater than an equivalent, vulnerable, and expensive satellite link. Understanding these differences can aid in making informed decisions regarding communication strategies in military operations.

Operating in a satellite and GPS/GNSS-denied environment:

Troposcatter communication can operate in satellite-denied environments where other forms of communication, such as satellite communication, may be unavailable or unreliable. This makes it a valuable technology in military operations that require reliable communication in areas where satellite communication may be disrupted or jammed.

Overall, the high-bandwidth capabilities and resilience to interference from terrain and weather make troposcatter communication a valuable technology in military operations. Additionally, the ability to operate in satellite-denied environments makes it a critical technology in modern military operations where reliable communication is essential to success.

Limitations of Troposcatter Communication

While this form of communication has several advantages over other forms of communication, it is not without limitations. Some of the commonly cited limitations of Troposcatter Communication include signal attenuation and degradation over longer distances, dependence on environmental factors such as atmospheric conditions, and equipment size. However, recent advances in technology have mitigated these, limitations and provide reliable, secure, and high-capacity communication over long distances.

Siting

When considering the use of Tropo for military communication links, it is essential to understand that it is not suitable for all scenarios. A clear take-off is required for a successful link, with typical elevation angles often less than +/-1 degree. Siting is critical for the success of a Tropo link, and to assist with this, the QUICK Tropo planning tool is utilised. This tool is easy to use and intuitive, enabling the identification of viable links rapidly.

The “Optimize” function within the QUICK Tropo planning tool is particularly useful, as it makes multiple rapid calculations and identifies the best location for both ends of the link. It is important to note that this location is unlikely to be co-located with the associated HQ, (which is not a good idea when fighting a peer-on-peer adversary). Instead, it is likely to be a short distance away, suitable for a short DLOS or Fibre Optic connection. Proper planning and optimisation can result in a reliable and effective Tropo link for military communication needs.

Signal attenuation and degradation over longer distances:

In the past large static antenna and very high power was required to use the Troposphere and overcome signal degradation over longer distances. Before 2005, modems were limited to 8Mbps or below and were large and unwieldy.

Advances in technology steadily increased data rates up to 50Mbps but development of Field Programable Gate Arrays (FPGA) and Digital Signal Processing (DSP) led to the development of the Software defined CS67Plus Modem radio with a capacity of up to 210 Mbps of full duplex data throughput. using a wide selection of modulation techniques from BPSK to 64APSK, coupled with powerful Low Density Parity Check (LDPC) Forward Error Detection and Correction allow Tropo to work effectively close to and even below the noise floor.

Advanced Troposcatter Systems provide high-capacity, low-latency data links over longer distances without the need for satellites or multiple line-of-sight repeaters. In addition, the relatively low power, complex waveforms and directional antenna systems make tropo resilient and robust to enemy electronic warfare.

Dependence on environmental factors such as atmospheric conditions:

Modern troposcatter systems are designed to work within these environmental constraints. The non-homogeneous elements present in the lowest level of the atmosphere, such as water vapor, dust, and atmospheric variations, are used to scatter a small portion of the transmitted energy forward in a predictable manner.

Limited bandwidth compared to other forms of communication:

Legacy systems worked at 8 Mbps and below. Recent advances in technology enable Advanced Troposcatter Systems provide high-capacity data links that can support modern communication needs. These systems are versatile and can be used in a variety of scenarios, ranging from portable transit case systems to large, fixed installations, offering far greater beyond-line-of sight bandwidths than satellite.

Equipment size:

The old systems were large and unwieldy. Modern troposcatter systems have been designed to be more compact and portable than their legacy counterparts. Terminals can range in size from a man-portable transit case system (COMET) to a vehicle-mounted system or large fixed installation, offering a wide range of options to meet specific needs. The Modern 500W MTTS is rapidly deployable, can be set up within 30 mins and acquire a link up to 250km in a further 30 mins. The smaller 10W COMET system has a range of up to 70km and can be set up and a link established within 15 mins. A combination of MTTS and COMET can rapidly cover an Operational area and extend the Digital Backbone to the Tactical edge.

Overall, while Troposcatter Communication may have some limitations, Advanced Troposcatter Systems have been specifically designed to address many of these limitations and offer a reliable, secure, and high-capacity communication solution over long distances.

Applications of Troposcatter Communication in Military Operations

Troposcatter communication has become an increasingly important technology in military operations due to its reliability and independence from satellites. It can function in a GPS/GNSS denied environment, making it suitable for use in a Peer-on-Peer conflict and to support multi-domain integration, including pan-government and with allies.

Independent of Satellites

Troposcatter communication is a critical technology that provides secure and reliable communication links without relying on satellites. In military operations, this is particularly important as satellites and Satcom systems are becoming more vulnerable to interception and disruption from non-allied countries potential adversaries. Troposcatter communication’s independence from satellites makes it a reliable and cost-effective alternative for secure communication, ensuring critical voice and data communication is transmitted securely around the operating area.

Low Latency and Wide Bandwidth

Troposcatter communication offers very low latency and wide bandwidth, making it suitable for large, deployed HQs and mobile battlegroups. Its ability to provide wide bandwidth enables analysis and manipulation of large data sets, which is critical for real-time decision-making on the battlefield. Additionally, its high mobility makes it suitable for more mobile battlegroups or even down to company headquarters.

Effective in Polar Regions

Unlike geostationary satellites, troposcatter communication is effective in polar regions. This is particularly important for military operations in the increasingly important Arctic and Antarctic regions, where traditional communication infrastructure may be unavailable or difficult to deploy.

Difficult to Detect

Troposcatter communication is highly suitable for many of the challenges faced by UK Defence and NATO today. Its directional nature, low power usage, and complex waveforms make it difficult to detect, providing a level of security and protection against interception or disruption.

Future of Troposcatter Communication

Troposcatter communication has proven to be a reliable and effective means of communication over long distances, without relying on traditional communication infrastructure or satellite systems. As the technology continues to advance, there are several potential areas for future development, including advancements in antenna technology and signal processing, as well as improvements in size, weight, and power.

Advancements in Antenna Technology and Signal Processing

One of the areas for potential advancement in troposcatter communication is in antenna technology and signal processing. As antenna technology continues to evolve, new materials and designs can be used to create smaller, more efficient antennas that are more portable and easier to deploy. Additionally, improvements in signal processing can lead to more accurate and reliable communication, even in challenging environments.

Advancements in antenna technology and signal processing can significantly enhance the capabilities of troposcatter communication, making it more reliable, secure, and versatile. These improvements will make it easier to deploy in challenging environments and provide a valuable alternative to traditional communication infrastructure and satellite systems.

Advancements in Size, Weight, and Power

Another area for potential advancement in troposcatter communication is in size, weight, and power. As technology continues to evolve, it is becoming increasingly possible to develop smaller, more lightweight systems that consume less power. This makes it easier to deploy and use troposcatter communication in a variety of environments, including those where traditional communication infrastructure may be unavailable or challenging to deploy.

By reducing the size, weight, and power consumption of troposcatter communication systems, it becomes possible to deploy them in more mobile configurations, including on vehicles or Maritime platforms This enables troops to communicate effectively while on the move, improving situational awareness and mission effectiveness.

In conclusion, troposcatter communication is an increasingly important technology in military operations. Its independence from satellites, low latency, wide bandwidth, effectiveness in polar regions, and difficulty to detect make it a valuable alternative for secure communication. As military operations become increasingly complex and dynamic, troposcatter communication will grow in importance in the critical role of ensuring secure and reliable communication links.