Wednesday, September 28, 2022

Top 10 Navies in the World | Defenceaviationpost.com

Top 10 Navies in the World | Defenceaviationpost.com

The World’s Top 10 Navies 
9h

Which navy is the strongest in the world? How strong are the top 10 navies?

Our list of the top 10 navies is based on the ships and submarines in their fleets. This analysis looks at how well the world’s navies can attack.

At the moment, these are the top 10 most powerful navies in the world:

United States


Image credit : Business Insider

At the moment, the US Navy is the most powerful navy in the world. After the Cold War ended at the beginning of the 1990s, the US Navy changed its focus from preparing for a large-scale war with the Soviet Union to preparing for small-scale wars in other parts of the world. The US fleet keeps getting smaller because funding is getting less and there aren’t enough threats. However, most of the big ships and the deadliest submarines are being replaced by smaller ones. The US fleet is well taken care of. New ships and weapons keep coming out. Nearly 320 000 people work for the US Navy.

The US Navy has 11 big ships called aircraft carriers that are used to show power. There is one aircraft carrier from the Ford class and 10 from the Nimitz and Improved Nimitz classes. Each of these aircraft carriers can hold between 70 and 80 planes. It is bigger and stronger than the whole air force of many countries. The aircraft carriers are used in groups called “carrier battle groups.” They are accompanied by a large number of warships and attack submarines. These escorting ships and boats protect the carriers from threats that come from the air, sea, and underwater. Also, these escorts give the strike force more ways to attack.

The US Navy has a lot of power to attack from the water. Eight to nine America class and Wasp class amphibious assault ships are used by the so-called “gator navy.” Each of these warships can hold between 1,700 and 2,000 marines and their armoured vehicles. Tiltrotors, helicopters, and hovercraft bring the marines and their vehicles ashore. Most aircraft carriers aren’t as big as these warships. There are also 11 large amphibious transports of the San Antonio class that can also go on long-range amphibious missions. Even though it is not part of the US Navy, the US Marine Corps has more than 180 000 people in it and its own naval aviation.

There are 22 cruisers that belong to the Ticonderoga class. These were the first surface combatant ships to have the most advanced air defence system in the world, called AEGIS. These cruisers are made to stop missile attacks on battle groups.

The US Navy is making 3 Zumwalt class destroyers that are very advanced and can hide in plain sight. These destroyers are the biggest ones ever made. In fact, the Zumwalt class ships are more like cruisers than destroyers because of their size, weight, and weapons. The main goal of these warships is to attack on land, but they can also do anti-aircraft and naval fire support. There are also 64 general-purpose destroyers from the Arleigh Burke class. Their weapons and systems are very advanced.

The US Navy does not have any frigates in use. Instead, Freedom- and Independence-class littoral combat ships have been put in their place. These small ships don’t have many weapons and aren’t made to fight against ships of the same size.

The US Navy has three Seawolf class nuclear-powered attack submarines. These submarines are very advanced. The boats that other countries use are not nearly as advanced as these ones. There are also 35 older Los Angeles class boats and 14 new Virginia class boats in use.

There are 14 Ohio class boats that are still in use and can carry ballistic missiles with nuclear tips. These ballistic missile submarines patrol in waters close to the US or in the more remote parts of the world’s oceans. This makes it almost impossible to take effective anti-submarine measures.

The US Navy has more than 3,700 planes. Most of them are multi-role fighters from the F/A-18 series and other planes that are also used on aircraft carriers.

Russia


Image credit : REUTERS

After the Soviet Union broke up, the Russian navy took over the fleet of the Soviet navy. Since the end of the Cold War in the early 1990s and ongoing problems with money, the size of the Russian fleet has shrunk by a lot. Most of its ships are left over from the Cold War. Due to a lack of money, the Russian navy has had trouble keeping its big warships in good shape for the past 20 years. Still, with around 140 000 people and a lot of warships and submarines, it is still a very strong force.

The Admiral Kuznetsov is the only aircraft carrier that the Russian navy has. It can’t do as much as the American carriers and can’t carry as many planes. Even so, it is still a strong and dangerous ship. Accidents and plane crashes happen a lot while the Admiral Kuznetsov is in service with the Russian navy. The ship’s system for moving forward isn’t working right. Russia has a hard time keeping its only aircraft carrier in good shape and working. Russia has no plans to build a new ship to replace this one right away.

The Russian navy only has one Petr Veliky battlecruiser, which they seem to have trouble keeping in good shape. Also, there are two smaller Slava-class missile cruisers that are very good at fighting ships, planes, and submarines.

There are about 15 destroyers, some of which are anti-submarine destroyers from the Udaloy class and general-purpose destroyers from the Sovremenny class. There are also about 24 corvettes and 9 frigates.

The Russian naval infantry is not very big. There are only about 12,000 people in it. Marines are dropped off on land by a single amphibious transport ship from the Ivan Gren class. There are also 14 landing ships from the Ropucha I and Ropuch II classes and 4 landing ships from the Alligator class. These ships can go from water to land and back again over a long distance. But compared to their US counterparts, the Russian amphibious transports are much smaller and less capable.

The Russian navy has a number of attack submarines that are powered by nuclear energy. There are a few nuclear-powered boats in the Akula class. These boats make up about half of Russia’s fleet of nuclear-powered attack submarines, which is getting smaller. A couple of new Graney class boats that run on nuclear power are being built. Also, there are 3 submarines of the Oskar II class that carry cruise missiles. These attack submarines are the biggest ones ever built, and they are meant to attack US aircraft carrier battle groups and coastal installations. Also, diesel-powered Kilo class patrol submarines are used to protect naval bases.

It looks like the Russian navy is putting a lot of money into its new ballistic missile submarines of the Borei class. Three of these boats are already in use, and another five are being built at a pretty fast rate. Intercontinental missiles with a nuclear warhead are on these boats. There are also a few older ballistic missile boats from the Delta IV class that are also a big threat. It’s important to remember that older Russian submarines of all types might be less ready to go due to a lack of money.

On paper, the Chinese navy has more ships and more tonnes than the Russian navy. But the Russian navy has a number of ballistic missile submarines that have been tested and are very dangerous.

Russian naval aviation has about 360 planes, including a small number of Tu-142 long-range anti-submarine warfare aircraft, Il-38 medium-range anti-submarine warfare aircraft, and Su-24 tactical bombers.

China


Image credit : By eng.chinamil.com.cn

The People’s Liberation Army Navy is what the Chinese navy is called by name. It was mostly a riverine and coastal force until the late 1980s. China has been adding to its fleet since the early 1990s. At the moment, new warships and submarines are being built quickly. About 255 000 people work for the Chinese navy. In terms of the number of tonnes, it is the second largest navy after the US Navy. Also, the most important fighters are in this war.

By 2018, the Chinese navy only had one aircraft carrier, the Liaoning. It is mostly used to teach people how to sail. But in 2019, the Shandong, a ship with a similar design, was put into service.

About 30 destroyers, 50 frigates, and 40 corvettes are in the fleet. Even though some of the older warships are not as good as their Western or even Russian counterparts. On the other hand, very advanced new warships are being built very quickly. Also, about 5 or 6 guided missile cruisers from the Type 055 class are almost done and should be ready to go by 2020.

The Chinese amphibious assault forces use 32 tank landing ships, 31 medium landing ships, and 4 amphibious transport docks. There are 10,000 marines in the Chinese navy who can be sent to hostile shores.

A fleet of 68 submarines is run by the Chinese navy. These are 4 ballistic missile submarines of the Jin class. They are powered by nuclear power and can carry intercontinental ballistic missiles with nuclear warheads. But so far, these missile submarines haven’t done any operational deterrence patrols. This could be because of problems or flaws in the way they were built. Still, there is a good chance that these missile boats will survive the first attack once the country has been attacked. There are also 13 Song class diesel-powered patrol submarines and 15 Yuan class diesel-powered patrol submarines. There are also two Shang class nuclear-powered attack submarines, one Qing class diesel-powered attack submarine, and 15 Yuan class diesel-powered patrol submarines.

More than 700 planes are also used by the Chinese navy. Its main job is to protect the fleet from air attacks. Over 140 fighters can do more than one thing. A number of JH-7 maritime attack aircraft and more than 30 H-6 medium-range bombers are also used by the Chinese naval aviation. The US carrier battle groups are meant to fight with these.

Japan


Officially called the Japan Maritime Self-Defense Force (JMSDF), Japan’s navy is made up of 50,800 people, over 150 ships, and almost 346 planes. Japan’s constitution says that the Maritime Self-Defense Force can only teach defensive tactics.

It runs warships and submarines that are very advanced in terms of technology. Also, the Japanese navy is kept in a state of high readiness and works very well. So, Japan’s navy doesn’t have as many warships or as much weight as China’s navy, but Japanese warships are usually more advanced and have more cutting-edge weapons. The JMSDF, on the other hand, doesn’t have any nuclear weapons.

There are no aircraft carriers in the Japanese navy, but there are two big Izumo class and two small Hyuga class helicopter carriers. These ships can do more than one thing. They can be used for amphibious operations, war against the surface, and war against submarines. The Maritime Self-Defense Force can project a lot of force with the help of these big helicopter carriers. As a response to China’s fast fleet growth, it was announced in 2018 that the Izumo class warships will be rebuilt as aircraft carriers.

The Japanese navy has 26 destroyers, including 2 large anti-air destroyers of the Atago class and 4 large general-purpose destroyers of the Kongou class. In fact, these military ships are almost as big as cruisers. Also, there are 4 destroyers of the Aikizuki class.

There are about ten frigates and six small destroyers (corvettes).

The JMSDF has 3 big ships that can land. The Marines of Japan are not very big, with just over 3000 people. The Japan Ground Self-Defense Forces are in charge of this naval infantry. The official job of Japan’s marines is to attack and take back islands that have been taken. Even though Japan is slowly putting together more expeditionary units.

About 20 submarines are part of Japan’s navy. These attack submarines are interesting because they are powered by diesel. Japan doesn’t use military warships that are powered by nuclear energy, so it built diesel-powered boats with advanced technology that can stay at sea longer and do a lot of damage. But Japan doesn’t have any nuclear ballistic missiles or ballistic missile submarines.

There are about 70 Lockheed P-3C Orions and 12 Kawasaki P-1 maritime patrol planes in Japan’s naval aviation.

United Kingdom


Image credit : CROWN COPYRIGHT

The official name for the Navy of the United Kingdom is the Royal Navy. From the middle of the 18th century on, the Royal Navy was the strongest navy in the world. It had power that no one else could match, and it was a key part of building the British Empire. It wasn’t until World War II that the US Navy was able to do better. The Royal Navy is currently focused on expeditionary operations and is still one of the best blue-water navies in the world. But because of less money, its size and number of warships are slowly shrinking. At the moment, there are about 33,000 people in the Royal Navy.

The Queen Elizabeth class aircraft carrier is the only type of ship used by the Royal Navy. The second ship of this class is expected to be put into service in the coming years. Even though these are smaller than Russian and Chinese carriers and a lot smaller than US carriers.

The British navy has six anti-air warfare destroyers from the Daring class. These ships can patrol large areas and defend the fleet’s airspace. Along with the Daring class destroyers, there are also 13 Duke class frigates. Most of the time, these frigates are used to fight against submarines.

The Royal Marine Commando Brigade is a well-known part of the Royal Navy. About 7,700 people are in this brigade. The Royal Marines are the best naval infantry force in the European Union. There are three logistical landing ships from the Bay class next to two landing ships from the Albion class.

There are 3 nuclear-powered attack submarines of the Astute class that are still in use. Four more boats of this type are being built. There are also 3 nuclear-powered attack boats from the Trafalgar class that are still in use but will be phased out over the next few years.

The Royal Navy also has 4 ballistic missile submarines of the Vanguard class. Each of these ships can hold up to 192 nuclear bombs. This much weight is enough to wipe out whole countries. At any given time, only one Vanguard-class boat is on a deterrence patrol. Information about these patrols is still very secret.

Most of the time, the British Fleet Air Arm uses naval helicopters for search and rescue, anti-submarine warfare, utility, and other tasks. Both the Sea Harrier and the Harrier II close support aircraft were taken out of service in 2006 and 2011. As a replacement, a number of F-35B stealthy multi-role fighters were ordered. These will be run from the new aircraft carriers in the Queen Elizabeth class.

France


Image credit : French Navy Photo

One of the oldest naval forces in the world is the French Marine Nationale. It has about 36,000 employees right now.

The Charles de Gaulle aircraft carrier is the only ship used by the French navy. It is the French navy’s main ship. It is the only aircraft carrier built outside of the United States that runs on nuclear power. But it is a lot smaller than US airlines. Plans were made for a second aircraft carrier that would be like the British Queen Elizabeth class, but these plans were eventually scrapped.

There are 2 modern anti-air destroyers from the Horizon class. The official name for these ocean-going warships is “frigates.” But these ships are clearly destroyers because of their size and powerful weapons. The only reason these are called frigates is because of politics. There are also two older destroyers from the Cassard class and four from the Georges Leygues class that should be taken out of service soon.

The French navy has four guided missile frigates from the Aquitaine class. More ships like these are being made. The Cassard class and Georges Leygues class destroyers will soon be replaced by the Aquitaine class frigates. There are 5 frigates from the La Fayette class and 6 frigates from the Floreal class.

The French navy has three amphibious assault ships from the Mistral class. After the Charles de Gaulle aircraft carrier, these are the biggest warships. The main job of these ships is to help people land on land. They also have the ability to give orders and move forces. A naval infantry brigade with about 8,000 people is part of the French navy. These are expeditionary forces that can be dropped off on enemy shores and go on armoured raids up to 100 km into enemy territory.

There are two attack submarines of the Rubis class and four of the Amethyste class. These are the smallest attack boats with nuclear power. France is making new nuclear-powered attack submarines of the Sufren class to replace the ones they already have.

The French navy has four ballistic missile submarines from the Le Triomphant class. These submarines are the main part of France’s nuclear deterrent.

The French naval aviation has about 210 planes, both those that fly from the ground and those that fly from aircraft carriers. These include Rafale multi-role fighters that can be used on ships, E-2C Hawkeye early warning aircraft that can be flown from a carrier, and Atlantique II maritime patrol aircraft.

India


Image credit : Wikipedia

About 67 000 people work for the Indian Navy. In South Asia, it is a strong force. It is slowly getting better equipment and changing from a coastal force to a force that can go out into the ocean. The Chinese navy, on the other hand, is much bigger and has a lot more power.

At the moment, the Indian Navy only has one aircraft carrier, the INS Vikramaditya. The number of planes on this carrier isn’t very big. The INS Vikrant is another aircraft carrier that is being built in India. It should be ready for use soon. It will make India’s ability to project force much stronger.

The Indian Navy has 11 destroyers, three of which are Kolkata class guided missile destroyers. These new destroyers are some of the most powerful in the world. There are also 5 older Rajput class destroyers and 3 Delhi class destroyers.

The Indian Navy has 13 frigates that they use. Some of them have modern designs, like the 3 Shivalik class and 6 Talwar class guided missile frigates. Also, there is one Godavari class frigate and three older Brahmaputra class frigates.

Also, there are about 20 corvettes whose job is to protect the waters along the coast.

The Indian Navy has one big landing ship called INS Jalashwa and 8 smaller ones called landing ships (3 Shardul class, 2 Magar class, 3 Kumbhir class). These ships are made to send troops and their gear to enemy shores or to launch a counterattack on Indian shores that have been taken. But India doesn’t have a dedicated naval infantry because it doesn’t have the right tools.

The Indian Navy has one submarine from the Arikhant class that can carry ballistic missiles. Soon, the second boat of this class will be put into service. These ballistic missile submarines powered by nuclear power were designed and built in secret. It was a big step in how the Indian Navy grew and changed. India is now one of six countries that can design and build submarines that can run on nuclear power.

There is only one attack submarine that runs on nuclear power. The INS Chakra is a Russian submarine from the Akula II class that India has rented. Also, the Indian Navy is getting new diesel-powered patrol submarines of the Kalvari class. Some changes were made to the French and Spanish Scorpene class boats before they were built for the Indian Navy. The first boat was put into service, two more boats should be ready soon, and three more boats are being built. The Indian Navy also has 9 diesel-powered patrol submarines of the Sindhughosh class. These are old Soviet Kilo class boats from the time of the Cold War. There are 4 diesel-powered boats of the Shisumar class (German Type 206 class) that are still in use.

There are about 210 planes in the Indian Naval Air Arm. There are different kinds of aircraft that can be used from a carrier, as well as 8–12 modern Boeing P-8I Neptune and about 5 older Ilyushin Il-38 maritime patrol aircraft.

South Korea


Image credit : MCS2 Michael Achterling

A few decades ago, not many people knew about the South Korean navy. But just recently, it went from being a coastal force to a force that can go out to sea. At the moment, 70 000 people work there.

There are no aeroplane carriers in the South Korean navy. But there is only one ship of the Dokdo class that can land on water. The size is about the same as that of light aircraft carriers. It is the navy’s most important ship. Another ship in this class is being built, and it will be ready to go to work in 2020.

There are 3 guided missile destroyers that belong to the Sejong the Great class. These warships are some of the most advanced ones on the water right now. After the American Zumwalt class, these are the most powerful destroyers in the world right now. The ships in the Sejong the Great class have a wide range of missiles and can deal with almost any threat on the water, on land, or in the air. When it comes to size and weapons, these ships are more like cruisers. There are also 6 destroyers of the Chungmugong Yi Sun-sin class and 3 destroyers of the Kwanggateo the Great class (though some refer these warships as frigates).

There is one Daegu class air defence frigate in service, which was put into service in 2018. Three more of these types of warships are being built right now. There are also six coastal defence frigates from the Incheon class. Six old frigates from the Ulsan class are used by the South Korean navy. These ships were built between the early 1980s and the early 1990s. Even though these older ships are going to be taken out of service soon.

The South Korean navy has seven diesel-powered submarines from the German Type 214 class, which are called Sohn Won-yil class in South Korea. There are also 9 older diesel-powered subs from the Chang Bogo class.

The South Koran Marine Corps is based on the US Marine Corps and has about 29,000 people working for it. If there is a war, these forces could be sent to North Korea and other islands. There are 2 amphibious landing ships of the Cheong Wang Bong class that are still in use. Two more of these kinds of ships are being built right now. Also, there are 4 ships of the Go Jun Bong class that can land on water.

About 70 planes make up the South Korean naval aviation. The majority of these are, in fact, helicopters. Despite the fact that there are 16 Lockheed Martin P-3C Orion maritime patrol planes.

Italy


Image credit : Getty Images

The Italian navy, which is officially called the Marina Militare Italiana, has about 31,000 people and a fleet of ships that can go out to sea. All kinds of warships are used by the Italian navy.

Only one Cavour light aircraft carrier exists. It is the Italian navy’s most important ship. It can run both V/STOL planes (like the Harrier and the F-35B) and helicopters. The Cavour can also carry both soldiers and military vehicles. A smaller aircraft carrier named after Giuseppe Garibaldi that is used by the Italian navy. There is also a lighter aircraft carrier named after Giuseppe Garibaldi.

The Italian navy has two destroyers from the Horizon class. Because of politics, these warships are called “frigates” by the government. But these ships are clearly destroyers because of their size and powerful weapons. Also, there are two old multi-role destroyers from the Durand de la Penne class. The Italian Navy has 6 smaller guided missile destroyers from the Carlo Bergamini class, and 4 more are being built and should be ready soon. These ships are also called “frigates” by the government, but they are much bigger and stronger than most frigates and even some destroyers.

Six anti-submarine frigates of the Maestrale class are currently in use. Even though all of these warships will be taken out of service in the next few years. There are two small patrol frigates of the Soldati class.

The Italian navy has a San Marco marine brigade with 3,800 people. This amphibious brigade is made up of 3 amphibious transport ships of the San Giorgio class. The San Giusto, the third ship in the class, is built better and can carry more troops. At the moment, Italy is building one Trieste amphibious assault ship, which will be put into service in 2022. Once it is in use, it will replace the Giuseppe Garibaldi light aircraft carrier, which is not as good.

There are 4 diesel-powered boats from the Salvatore Torado class (German Type 212 class) and 4 diesel-powered patrol submarines from the Sauro class, which are older.

There are 2,000 people in the Italian naval aviation, and they use 12 AV-8B Harrier II close support planes. Another 29 to 30 F-35B fighters that can be used in many different ways were ordered for use on Italian aircraft carriers. There are a small number of maritime patrol planes, but the Italian air force, not the Italian navy, is in charge of them.

Taiwan


Image credit : file image

There are 38 000 people in the Taiwanese navy. The United States is where it buys most of its warships. Some warships came from countries other than the United States. Taiwan is also able to build its own ships, though.

On this list of the Top 10, the Taiwanese navy and the Indonesian navy were tied for the 10th spot. Even though the Indonesian navy has twice as many people and a lot more ships, most of its fleet can only operate near the coast, while the Taiwanese navy has a number of frigates that can go out to sea. Another strong player that didn’t make this Top 10 list was the Turkish navy. It is also strong and has a strong coastal fleet that is mostly used in the Mediterranean.

There are 4 ships of the Kee Lung class. These used to be US destroyers from the Kidd class. Even though the ships were fixed up and made better before they were given to the Taiwanese navy.

Twenty frigates are used by the Taiwanese navy. There are eight frigates from the Cheng Kung class. The US Oliver Hazard Perry class was used to make these warships, which were made in Taiwan. There are 6 frigates from the US-built Knox class and 6 frigates from the French-built La Fayette class.

There are a total of ten ships that can land. One is a Hsu Hai, which used to be a US Anchorage class ship, and the other two are Chung He class ships (former US Newport class).

The Taiwanese navy only has two useful submarines from the Hai Lung class. These boats are Dutch Zwaardvis class boats that were brought over in the 1980s.

Taiwan’s naval aviation uses 12 P-3C Orion maritime patrol planes that have been fixed up and made better.

The post The World’s Top 10 Navies  appeared first on Defence Aviation Post.

 

Tuesday, September 27, 2022

[2205.07216] FedHAP: Fast Federated Learning for LEO Constellations Using Collaborative HAPs

[2205.07216] FedHAP: Fast Federated Learning for LEO Constellations Using Collaborative HAPs

High Reliability and Radiation hardened memories for space and aerospace applications

 

High Reliability and Radiation hardened memories for space and aerospace applications
5h

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The space race between countries has intensified from exploration and mining of the moon and asteroids,  launching large LEO constellations for providing global connectivity monitoring earth to NASA’s $10 billion James Webb Space Telescope.

 

Over the past three years, SpaceX has deployed thousands of satellites into low-Earth orbit as part of its business to beam high-speed internet service from space. But the company’s latest deployment of 49 new satellites after a Feb. 2021 launch did not go as planned.

 

As a consequence of a geomagnetic storm triggered by a recent outburst of the sun, up to 40 of 49 newly launched Starlink satellites have been knocked out of commission. They are in the process of re-entering Earth’s atmosphere, where they will be incinerated.

 

Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. Ensuring the reliable operation of microcircuits in outer space is an important scientific and economic objective. For modern weather, communications and surveillance satellites to be cost-effective, they need to be operational for at least 10 to 15 years.

 

But with extended space missions comes the requirement for flawless performance by on-board equipment over a period of years, in a very harsh environment. On takeoff, electronic components endure violent beatings from extreme vibration, and once in orbit, every material needs to be able to endure wildly shifting thermal changes that can see a cycle through 260 degrees Fahrenheit (126.67 degrees Celsius) every hour of every day.

 

Deep-space and long-duration missions, where both crew members and spacecraft no longer benefit from the protection of Earth’s magnetic fields, are considered high risk for adverse radiation impacts.  Aircraft flying at altitude, at about 30,000 feet and above, also are starting to experience radiation-induced effects. “There are 500 times more neutrons at 30,000 feet than there are on the ground,” points out Aitech’s Romaniuk. Long term exposure of astronauts to radiation is problematic and the effect that space radiation has on spacecraft electronics and software is equally challenging.

 

Future small satellite systems for both Earth observation as well as deep-space exploration are greatly enabled by the technological advances in deep sub-micron microelectronics technologies. For modern weather, communications and surveillance satellites to be cost-effective, they need to be operational for at least 10 to 15 years.  Onboard electronic equipment failures are a common reason for early satellite failure. But with extended space missions comes the requirement for flawless performance by on-board equipment over a period of years, in a very harsh environment. Ensuring the reliable operation of microcircuits in outer space is an important scientific and economic objective.

 

The emerging earth observation (EO/IR/SAR)  satellites all capture thousands upon thousands of terabytes of data every day, which equates to petabytes every year. And in the future, there will be even more data collected — NASA is planning two space missions called SWOT and NISAR that are expected to produce roughly 100 terabytes of data per day. Not all of this data can be sent back to earth in real time, nor should it, which means that effectively storing it in space is the only way of making this data useful and actionable.

 

To properly process and handle that data in space, to make that data useful, engineers have discovered acute requirements for data integrity to ensure that data retains the ability to be analyzed in space – or relayed back home for analysis. If data integrity is core to success in space, data storage is equally if not more important, for it’s the foundation on which data can be accessed, stored and analyzed.

 

Data storage in space needs to be able to endure the rigors of a space mission, from the challenges  relating to launch, orbit, and return to earth, and the evolution in data storage reliability has led to an evolution of advanced data storage use cases around us.

 

Semiconductor memory devices used in outer space, for example, in a satellite, are subjected to severe environmental conditions that may compromise the integrity of the stored data, or cause the memory devices to fail. In many cases, the memory devices are part of a larger embedded system, where the memory device is just one of many devices sharing the same die.

 

The integrity of the memory devices used in outer space applications is critical because the information stored by the memory devices may be related to critical functions, such as guidance, positioning, and transmitting and receiving data from a ground base station. Furthermore, semiconductor memory devices for use in space applications should remain functional for the lifetime of the satellite, which may be as long as several years. Contrast this with applications where the memory devices are also subjected to harsh operating conditions, such as guidance systems in missiles, but only for a relatively short time period.

 

Memory technologies

Digital information can be stored in different types of device depending on the use and how frequently the data need to be accessed. Hard disk drives are magnetic devices that allow storing terabytes of data for long time, however speed of access to the data is relatively slow (a few milliseconds). On the other hand, data that are being used by a computer processor to perform an operation need to be accessed on a much faster timescale (nanoseconds). Silicon-based semiconductor memories are categorized into volatile and nonvolatile memories.

 

Volatile memories, such as static random-access memory (SRAM) and dynamic random-access memory (DRAM), need voltage supply to hold their information while nonvolatile memories, namely Flash memories, hold their information without one. Most devices like smartphones and notebooks currently use a combination of dynamic random-access memory (DRAM) and flash memory, with the former acting as active memory while devices are on, and the latter being used to store data long-term (off or on).

 

Flash memory is widely used in consumer electronic products such as cell phones and music players. NAND Flash-based solid-state disks (SSDs) are increasingly displacing hard disk drives as the primary storage device in laptops, desktops, and even data centers. However, Flash is slow and has low endurance. The integration limit of Flash memories is approaching; NAND cannot scale down past 10nm while DRAM and SRAM are costly.

 

New nonvolatile memory technologies are emerging such as magnetic random-access memory (MRAM), spin-transfer torque random-access memory (STT-RAM), ferroelectric random-access memory (FeRAM), phase-change memory (PCM), and resistive random-access memory (RRAM), that combine the speed of static random-access memory (SRAM), the density of dynamic random-access memory (DRAM), and the nonvolatility of Flash memory and becoming very attractive for future memory hierarchies. Western Digital, owner of the SanDisk brand, has  unveiled what it calls the “world’s first” 1TB SD card. It’s only a prototype, but already the company is touting the card’s ability to adequately handle 4K, 8K, VR and 360-degree video when it officially becomes available

 

Radiation effects on memory

One cause of errors in semiconductor memory devices that are used in outer space applications is due to high-energy particles impinging on the memory device. There are several forms of high energy particles in outer space. For example, there are alpha particles and gamma rays, to name a couple. These high-energy particles strike the semiconductor material on which the memory devices are formed with enough energy to cause the generation of electron-hole pairs. The resulting charge carriers are often trapped in the various oxide layers of the memory devices.

 

In the case of metal oxide semiconductor (“MOS”) transistors, charges trapped in the gate oxide will shift the threshold voltage. Vt, of the transistor. As a result, leakage currents of the transistors, and consequently, of the memory devices may increase. Where the transistor is used as a transfer gate for a conventional memory cell, the increased leakage current may compromise the integrity of the data stored by the data storage node, such as a capacitor, by allowing the charge representing the data to dissipate.

 

The frequency or number of charges trapped in an oxide layer is proportional to the thickness of the oxide layer. Consequently, oxides having a greater thickness will, on the average, have a greater number of trapped charges.

 

Radiation hardening

Radiation hardening is process of making electronic components such as momeory  resistant to damage or malfunction caused by high levels of ionizing radiation (particle radiation and high-energy electromagnetic radiation), especially for environments in outer space and high-altitude flight, around nuclear reactors and particle accelerators, or during nuclear accidents or nuclear warfare.

 

Researchers have explored many concepts  for low-cost high-density Radiation-Hardened (RH) Non-Volatile Memory (NVM) for the design of systems for use in space environments. The general principles used to be insensitive to single event upsets is to use triple redundant logic and memories with error correcting codes (e.g. Hamming coding). Circuits with large memories and S-RAM based FPGAs should only be used in radiation environments after a careful analysis of single event upset problems. The problem of single event burnout in power MOSFETs can in many cases be resolved by using a de-rating factor of ~2 of the main voltage and current limitations of the power transistor (implies redesign of power supply).

 

Earlier  solutions relied  on inefficient hardening techniques, such as radiation hardening by design (RHBD), which weree implemented either in layout or in the application architecture and not in the fabrication process. Many of these solutions are based on redundancy and result in a performance penalty. Moreover, most aerospace applications preclude the use of moving parts, such as the one in a hard disk. Thus, an ultra-high density storage solution is completely lacking.

 

Efforts over the last two decades to develop a practical NVM solution for space have fallen short of the density and performance needs. A radiation-hard NVM that can achieve high density is needed. Commercial NVMs have greatly increased in density while reducing cost in recent years, creating a gap of more than six orders of magnitude between commercial and RH devices.

 

Western Digital’s Design for Reliability

Western Digital engineers have been working with companies in space on their approaches to data storage. Using an approach known as Design for Reliability (DFR) has become popularized as a standard engineering practice, which is intended to design reliability into products using state-of-the-art methods. As technology continues to advance and highly complex devices continue to shrink and miniaturize, DFR can ensure high-performance and low-voltage requirements so that new electronic components can overcome various limitations. DFR made leaps and bounds in space technology development, and the fruits of those labors are subtly penetrating more and more products.

 

Radiation hardened and tolerant memories

Infineon Technologies AG in Munich is introducing radiation-tolerant 256-megabit and 512-megabit NOR non-volatile Flash memory chips for space applications that involve field-programmable gate array (FPGA) configuration, image storage, microcontroller data, and boot code storage.

Qualified to MIL-PRF-38535’s QML-V flow (QML-V equivalent) the devices offer high quality and reliability standard certification for aerospace-grade integrated circuits.

Infineon’s 256-megabit and 512-megabit radiation-tolerant NOR Flash non-volatile memories deliver a low-pin-count, single-chip solution. When used at high clock rates, the data transfer supported by the devices match or exceed traditional parallel asynchronous NOR Flash memories.

The devices are radiation-tolerant to 30 kilorads (Si) biased and 125 kilorads (Si) unbiased. At 125 degrees Celsius, the devices support 1,000 program/erase cycles and 30 years of data retention and at 85 C 10,000 program/erase cycles with 250 years of data retention. Infineon leveraged the 65-nanometer floating gate Flash process technology to develop the radiation-tolerant 256-megabit quad-SPI (QSPI) and 512-megabit dual quad-SPI NOR Flash.

 

GSI technology introduced high-performance 288Mb SigmaQuad-II+ radiation-hardened SRAM product.” “The RadHard SigmaQuad™ SRAM leverages our proven commercial technology and architecture with radiation-hardening, creating an efficient, high performance, leading-edge memory at the 40nm technology node.” “The SigmaQuad™ SRAM product is expected to serve as a critical element for advanced systems that leverage leading-edge FPGAs, ADCs and DACs; but until now lacked the high density, high performance and power efficiency that our 288Mb memory brings,” said Paul Armijo, Aerospace & Defense Business Director of GSI Technology.

 

Cobham Semiconductor Solutions in Colorado Springs, Colo., is announcing QML V radiation hardened certification of their non-volatile semiconductor memory products. QML V involves especially rugged microelectronics devices that are qualified for space applications.

The MRAM-based product offering includes a 64-megabit device, UT8MR8M8, offered in a 40-lead quad flatpack, and a 16-megabit device, UT8MR2M8, available in a 40-lead flatpack.

 

 

 

 

References and resources also include:

https://patents.google.com/patent/US6194276

https://venturebeat.com/2022/03/05/data-storage-from-space-to-earth-3-takeaways-for-the-real-world/

Friday, September 16, 2022

Aero mobile Satellite communication technologies for Aircrafts and UAVs

Aero mobile Satellite communication technologies for Aircrafts and UAVs

IDST – International Defence, Security and Technologyby Rajesh Uppal 41m

The future of aviation worldwide is one of significant continuing growth in air travel, air cargo, and private general aviation. Passenger services communications are expected to generate revenue for airlines and service providers. They will require a “critical mass” of users to justify costly avionics installation and operating costs, hence they will need to be broadband services.

However, passenger aircraft remains one of the few places where ubiquitous data connectivity cannot be offered at high throughput, low latency and low cost. Airline and business jet passengers are demanding Internet connectivity as they travel across the globe. A survey by Honeywell revealed that nearly 75% of airline passengers are ready to switch airlines to secure access to a faster and more reliable Internet connection on-board and more than 20% of passengers have already switched their airline for the sake of better in-flight Internet access.

They will therefore evolve in a market-driven way, in fits and starts, with successes and failures dependent upon the quality and usefulness of service, customer acceptance, and service cost.  While the quality of service improves and costs are reduced, user demand for on-board communications connectivity will increase as the general public grows accustomed to ubiquitous access to wireless access in flights.

This is leading to increasing demand for high bandwidth data access on commercial aircraft for both business jets and major airliners. Until now such high bandwidth data links have been predominantly provided when the aircraft is over land, using a system of ground-based installations to provide the link to the aircraft. For full transcontinental coverage, SATCOM is the only effective way of providing connectivity with Inmarsat’s L-band coverage, for example.

In the future, to achieve the required bandwidths, the frequency of operation must move to the Ku-band or Ka-band to support data rates up to 1000 Mbps. New satellites are being launched that support higher frequencies to enable this increase in bandwidth.

SATCOM systems traditionally have utilized geostationary Earth orbit (GEO) satellites—satellites that relative to the Earth’s surface will stay in a fixed location. To achieve geostationary orbit, the satellite must be at a very high altitude—over 30 km from Earth’s surface. The benefit of such a high orbit is that very few satellites are needed to cover a large area of ground, and transmitting to the satellite is simplified because it has known, permanent coordinates. Due to the launch cost of these systems, they are designed for long lifecycles, resulting in a stable but sometimes antiquated system.

Because of altitude and radiation challenges, additional device screening or satellite shielding is often needed. Furthermore, because the satellite is so far away, there will be significant loss with the user on the ground, impacting signal chain design and component selection. The long ground-to-satellite distance also results in high latency between the user and the satellite, which can impact some data and communication links.

The proliferation of UAVs in the defense (and soon the commercial world), has created a new arena of SATCOM links. UAVs face similar challenges. The advanced defense-focused UAVs are required to operate around the globe with remote piloting, possibly from a different continent. These requirements drive a need for high bandwidth datalinks to support video, control, and advanced payload data, potentially saturating the existing communications infrastructure. With commercial UAVs also set to have expanded coverage in the future, global network high bandwidth connectivity will pose the same SATCOM challenges as in commercial aviation.

At the same time, supporting legacy data links, minimizing size, weight, and power (SWaP), and reducing investment in system development is driving a need to develop flexible architectures and maximize system reuse. Recently, many alternatives or complementing systems to GEO satellites have been proposed, with UAVs and low Earth orbit (LEO) satellites being considered. With lower orbits, these systems mitigate most of the challenges described with GEO-based systems, but at the expense of reach, with many more satellites or UAVs required for similar global coverage.

Challenges

Terminals in the aeronautical market work under one of the most difficult environments. Antennas carry very sophisticated requirements in terms of form factors (aerodynamic limitations), weight, pointing accuracy, reliability and many other technical requirements. Similarly, RF equipment has strong limitations in size and weight, while skyrocketing throughputs continuously demand more power. Modems orchestrate the link offering high-quality, high-speed communications in this challenging ecosystem.

Modems and baseband equipment operating in this vertical have very sophisticated requirements. The global nature of demand involves high initial CAPEX investments in baseband equipment. Routes and traffic patterns change depending on the season, and anytime of the day, which
requires very flexible networks. Consequently, requirements for the network management system are very sophisticated and include ensuring advanced Service Level Agreements for individual aircrafts and fleets running applications at different priority levels with planes constantly migrating to different beams and satellites — all this with end-users enjoying the highest standards of connectivity.

Ultimately, beam hopping and beam forming are capabilities that ground platforms and the space segment need to coordinate to optimally utilize capacity. Equipment must serve all these requirements, while meeting the stringent, expensive, and exhaustive certification process involved for any equipment used in the aeronautical sector.

Aeronautical channel model for satellite communications

Designing a satellite airborne technology for the military is significant technology advancement, yet it presents several distinct, technical challenges. Propagation effects of aeronautical channels differ from maritime and land mobile propagation because of the high velocity of aeroplanes, their distance from ground and influence of the aircraft body on antenna performance.

Aeroplane manoeuvres can affect signal under conditions when aircraft antenna is shadowed by the aircraft structure. When considering helicopters, the rotation of the rotor blades causes a cyclic interruption to the signal path.

An aeronautical channel model for satellite communications needs to consider two main contributions:
• a strong line of sight (LOS) component that is present all the time (except during maneuvers where the satellite signal might be blocked by the aircraft body) affected by ionospheric and tropospheric effects, and possibly by specular and/or diffuse scattering from the aircraft;
• a surface (ground, sea, ice, snow) scattering component which arrive with a certain delay, phase and attenuated power with respect to the LOS component.

The overall channel is considered time-varying due to various conditions: atmospheric dynamics, geometry changes due to aircraft flight (affecting not only the LOS, but also the fuselage scattering at each instant), dynamics of elements on the fuselage (e.g. blades for helicopters), time-variation of the surface scattering, and dynamics of the surface (e.g. sea waves). The effects of antenna pattern must not be neglected, the type of antenna may mitigate ground and fuselage multipath effects, but in cases such as banking maneuvers, multipath may arrive as strong contribution impacting the communications signal.

Researchers have designed a software tool for propagation analysis of satellite to aeronautical communications, including more physically based models, valid from VHF to Ka-bands, and which could take into account the following technical issues:
• modifications induced on the antenna pattern by its installation on the platform,
• geometry of the trajectory and platform dynamics during movements including the attitude,
• surface scattering effects for sea and ground surfaces, including vegetation layers,
• atmospheric effects due to troposphere at different altitudes and ionosphere.

Signal shadowing and multipath influence system design in a number of ways: signal blockage affects link reliability; and multipath noise causes errors in digital transmission.  frequency-selective fading causes inter-symbol interference when signal bandwidth exceeds the coherence bandwidth;

Airborne COTM networks must be able to efficiently and reliably support a wide range of throughput rates from basic email, to flash override Voice over IP (VoIP), to high-definition video.

These applications must operate on fast-moving aircraft, using a very small antenna and overcoming issues like the Doppler Effect and rain fade. An airborne COTM network must also support near seamless global coverage, track deployed units and manage beam switching while meeting stringent security and budget requirements.

The Doppler Effect is the change in frequency of a wave, as perceived by a receiving station, as either the transmitter or the receiver moves. Doppler frequency jitter appears as noise-causing detection errors, and Doppler frequency shift has to be compensated.

Historically, the Doppler Effect in satellite transmission has been a secondary consideration arising from the satellite’s motion in its station-keeping box. With highspeed vehicles such as aircraft, the Doppler Effect has a great impact on the effectiveness of demodulators. Therefore commercial aircraft systems such as  iDirect include built-in Doppler Compensation features that handle satellite frequency shifts to ensure seamless availability and performance.

LEO satellites potentially offer some relief. These operate at a much lower altitude—roughly 1 km off earth’s surface—but at this altitude they are not stationary, and in fact sweep across Earth’s surface, with an orbital cycle of roughly 30 minutes. The low altitude reduces the launch cost, and with a less harsh environment potentially less screening and shielding is needed. And critically, the low altitude means less propagation delay. But the primary difficulty for a LEO system is that the satellite is only within range of the user for fairly short bursts, necessitating the use of handoffs.

Technologies

Providing high-speed connectivity through small mobile antennas is one of the toughest challenges of airborne COTM. Sub-one meter antennas required for COTM have low gain characteristics. Higher power is required to ensure the receiving terminal hears the remote over the background noise created when the satellite boosts the signal. These high-rate signals coming from small antennas often cause interference with adjacent satellites that may be using the same frequency and polarization.

Advances in satellite manufacturing and directional earth-station technology, particularly the development of multi-axis stabilized earth-station antennas capable of maintaining a high degree of pointing accuracy, while stationary or on rapidly moving platforms, have made earth stations with very stable pointing characteristics both available and practical.

Network engineers must provide broadband connectivity to moving platforms without causing, or being impacted by, adjacent satellite interference. The solution is spread spectrum technology. Spread spectrum is a satellite router feature that diffuses high rate signals by “spreading out” the transmissions to minimize the interference to adjacent satellites without limiting connectivity to the target satellite. Yet, this can come at high bandwidth cost.

Automatic Beam Switching

Recent years have also seen several advances in satellite systems and networks, allowing better efficiency, reliability, increased data rates, and new applications. New paradigms such as mega constellations are manifest, triggering significant investments in future constellations. By 2020-2025 there will be more than 100 High Throughput Satellite (HTS) systems using Geostationary (GEO) orbits but also mega-constellations of Low Earth Orbit (LEO) satellites, delivering Terabit per second (Tbps) of capacity across the world.

Multibeam satellite systems have been specifically developed to allow efficient frequency reuse and high-throughput broadband rates across the coverage area, not unlike their terrestrial cellular counterparts. Satellite broadcasting via geostationary satellites will remain in widespread use. It will be a main source of revenue for satellite operators for the foreseeable future. But technology evolution in the coming years will also offer the possibility of new services via “very high throughput satellites (VHTS)” and “multispot” geostationary satellites, says ITU.

Military aircraft typically travel across multiple satellite beams. This presents an important service continuity challenge as an onboard remote must maintain a connection across these beams. iDirect handles this through a technology called Automatic Beam Switching (ABS). With ABS, iDirect remotes can travel across satellite footprints and maintain seamless connectivity without the need for manual intervention.

Ku-Band/Ka-Band

These systems often required two, and sometimes even three, stages of analog upconversion and downconversion, each requiring a synthesizer, amplification, and filtering that drives up system SWaP. However, to fit within the existing airliner infrastructure and power distribution system incorporating such signal chains for all the possible data links may be untenable.

The large number of components, power consumption, and isolation challenges means the printed circuit board (PCB) will be large. And because of the high frequency routing, more RF appropriate PCB material may be needed, significantly impacting cost. With a need to continue to support the L-band frequency of operation, the SWaP and design effort challenges are compounded.

Antenna requirements and technologies

Providing high-speed connectivity through small mobile antennas is one of the toughest challenges of airborne COTM. Sub-one meter antennas required for COTM have low gain characteristics. Higher power is required to ensure the receiving terminal hears the remote over the background noise created when the satellite boosts the signal. These high-rate signals coming from small antennas often cause interference with adjacent satellites that may be using the same frequency and polarization.

Global Network Management

To achieve global coverage, airborne remotes need to traverse networks on various transponders and satellites, controlled from a variety of hubs and networks. This poses a number of challenges for IP networks and Network Management Systems (NMS) regarding how to track and authenticate remote units, monitor service reliability and manage Service Level Agreements (SLAs). Security is a top priority for military operations. For mobile remotes on an IP satellite network, this means secure channel activity, control channel information, unit validation, physical security and data encryption.

References and Resources also include:

https://dial.uclouvain.be/pr/boreal/object/boreal%3A182406/datastream/PDF_01/view

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