Satellite communications today: A practical guide

From the time this blog is published till the time you read it, the number of human-made satellites in space will likely have increased – perhaps dramatically. In the past, satellite launches were rare and much anticipated events. But today, satellites are not only launched by governments, but by individual companies for a wide variety of purposes, with increasing regularity. It’s now as impossible to turn back the clock on satellite communications as it is to uninvent electricity.

History of satellite communication

The first artificial satellite was launched in 1957, sparking the space race between Russia and the USA. Over the next years, setbacks – failed launches, explosions, and calculation errors – became fewer and successes more frequent. There were many firsts in those early days: the first animal in space, the first deep space photography, and first satellites launched by various countries, to name just a few. 

In the 60’s satellites were experimental used primarily for earth measurement, planetary photography, and scientific research, however, starting in the 1970’s satellite for both domestic and international communications started to be deployed.

By the 2010’s, the number of satellites – and the applications for using them – increased dramatically. After 2020, the growth pattern spiked upward, taking on a hockey stick shape.

According to satellite tracking website Orbiting Now, there are now 11,829 artificial satellites in space* – almost ten times the number only two decades ago.

 

What is SATCOM today?

Satellite communication is a method of transmitting data, voice, and video signals using artificial satellites in Earth's orbit. It’s vital for communication anywhere without terrestrial infrastructure, like remote areas, islands, ships, and airplanes. 

Today, there are a wide variety of SATCOM applications, including:

Telecommunications. Satellite phone and video calls – made by sending data up to the satellite and back down to the person on the other end – connect people who would otherwise be isolated. (Internet connection works the same way.)

Television broadcasting and satellite radio. Direct-to-Home (DTH) satellite TV providers and satellite radio stations now reach remote audiences, including consumers in vehicles, often providing niche or exclusive content.

Scientific research. Satellites provide a unique vantage point from space to observe and study various aspects of our planet and the universe. They also facilitate data and sample collection from the moon and other planets.

Military and defense. Essential to military operations, satellites support secure communication, reconnaissance, surveillance, and missile warning systems.

Search and rescue / disaster management. Used for maritime and aviation emergencies, SATCOM helps locate and rescue individuals in distress. Satellites are also vital to disaster response and recovery.

Remote education and telemedicine. Isolated communities and people in rural areas rely on satellite internet and video conferencing to access remote learning and telemedicine services.

Connectivity in aircraft and ships. Offering in-flight WiFi and maritime communication services to passengers and crews, these systems provide entertainment as well as essential air-to-ground contact.

Mining and resource management. Assisting in monitoring and managing mining operations, SATCOM can also provide data used for environmental impact assessments.

Financial services. Secure and high-speed data transmission is essential for financial transactions, particularly in regions with limited terrestrial connectivity.

 

How does satellite communication work?

Satellite transmission involves sending signals from a ground station to a satellite, which then relays them back to Earth. Sounds simple – until you consider that these signals need to be transmitted over thousands of miles in space, through extreme heat and cold, and handed off from one system to the next. Without sophisticated technology that extends signal strength and cleans it from interference, there is no way signals could reach from Earth to space – let alone carry meaningful voice, data, and video information.

 There are several key steps in the satellite transmission process, each of which relies on sophisticated electronic and mechanical components:

• Ground station role: The ground station plays a crucial role in satellite communication. It's the initial point where digital signals are collected from a computer and modulated onto a carrier frequency, making them suitable for satellite transmission. Digital signals at this stage are in the form of ones and zeros, whether the information is voice, data, or video.
• Signal modulation and carrier frequencies: Digital signals must then be modulated onto a frequency used by the carrier (also known as the satellite operator). The modulator converts digital signals (the ones and zeros) onto the carrier frequency, typically around one gigahertz, which is then upconverted for satellite transmission. 
• Frequency conversion and amplification: Frequency conversion is necessary to transmit signals effectively to satellites. Signals are upconverted from around one gigahertz to higher frequencies (like 14 gigahertz) for better transmission. These signals are then amplified to compensate for signal loss in space.
• Satellite operations: When satellites receive these upconverted and amplified signals, they perform a variety of tasks, depending on their mission. For example, they might route signals to other satellites or collect data from onboard instruments to transmit back to Earth. Before they can do that, however, they need to perform frequency conversion once again and re-amplify the signals before sending them back. This process ensures that the signals remain strong enough to be received effectively.
• Signal reception and demodulation: Upon reaching Earth, the satellite signals, now at lower frequencies, are received. These signals are amplified and then demodulated back into digital format, making them usable for the end receiver 

Communications satellite design

A variety of sophisticated components are required to ensure that satellites can operate reliably in the harsh environment of space. The spacecraft bus serves as the satellite’s main structure and provides support for all other subsystems, including:

• Power system, which relies on solar panels to capture energy from the Sun and convert it into electrical power along with batteries that store energy.
• Thermal control that protects the satellite from extreme temperature variations in space.
• Attitude control that positions or orients a satellite in space with respect to various reference points, axes, or celestial objects. For larger adjustments or orbit changes, thrusters may be used to provide propulsion and control.
• Communications systems, including transponders that receive, amplify, and retransmit signals between the satellite and ground stations or other satellites – as well as antennas that direct the signal over a particular geographic area.
• Payload, which is the primary mission-specific equipment or instruments carried by the satellite. Examples include cameras, sensors, communication transponders, or scientific instruments, depending on the satellite's purpose.

Satellites are designed to communicate with the ground station and are reliant on frequency converters to translate signals from frequencies used on Earth to those used in space.

 

Satellite frequency bands

Radio frequency bands are portions of the electromagnetic spectrum with specific frequency ranges allocated for various activities and services. Below are some of the most common ones:

Types of satellites

Satellites can be categorized depending on the orbit they are designed to travel in:

• Geostationary Earth Orbit (GEO). Satellites in GEO are positioned approximately 22,236 miles above the Earth's equator. This altitude allows them to maintain a fixed position relative to the Earth's surface – so from the ground, these satellites look like they are stationary. Commonly used for communication and broadcasting, GEO satellites are ideal for providing continuous coverage to a designated geographic area.
• Medium Earth Orbit (MEO). MEO satellites operate between GEO and LEO – at altitudes ranging from approximately 1,243 miles to 22,236 miles above the Earth’s surface. MEO is the orbital region where navigation satellite constellations like the Global Positioning System (GPS) are situated. These satellites provide accurate global positioning and timing information for navigation and location-based services.
• Low Earth Orbit (LEO). LEO satellites operate at a much lower altitude – between 99 and 1,243 miles above the Earth’s surface. They have shorter orbital periods and higher speeds, so they orbit the Earth more frequently. LEO satellites are used for everything from weather reporting and climate change monitoring to scientific research to satellite phone communication and global internet services. Smaller and less expensive than other types of satellites, LEO satellites are driving much of the growth in the industry today.
• Highly Elliptical Orbit (HEO). Less common than GEO, MEO or LEO, HEO satellites follow elliptical orbits, which means their paths around the Earth are elongated, resembling an oval shape. Their use is often driven by specific mission requirements.  

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 Future of satellite communication

The single word that best describes the future of SATCOM is “innovation” – just as it describes satellite history to date. As new requirements for communication emerge, satellite technologies and products can be expected to rise to the challenge.

Here are a few specific predictions:

Satellite communication will continue to bridge the digital divide, equipping people in remote areas with the connectivity they need to fully participate in the global economy. And as a critical enabler for the Internet of Things (IoT) and machine-to-machine communications, it will support new applications that haven’t yet been imagined.

Security and cybersecurity will also be of paramount importance. Secure and resilient satellite networks will be increasingly integral to critical infrastructure, particularly in military communications.

As space tourism and exploration expands, satellites will play a vital role in maintaining contact between spacecraft and communication teams on Earth.

Interplanetary communication is also on the horizon. With plans for human missions to Mars and beyond, there will be a need for advanced communications systems to maintain contact with astronauts and robotic missions.

And of course, there are challenges as well as opportunities. Environmentally sustainable practices will be a major focus as the industry strives to minimize space debris. Regulatory challenges will also be front and center as companies and countries navigates issues related to spectrum allocation, airspace sovereignty, debris mitigation, and international cooperation – not easy tasks.

But one thing we can predict with confidence – satellite systems will have more and more impact on our daily lives as we move forward. Because SATCOM is as unlikely to stand still as are the satellites orbiting in the sky above us.