[ By Electronics Infoline Editorial Team ]
Feature Image by Mali Maeder from Pexels
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The present age is the age of information. Computing systems are penetrating all areas of life at an ever-increasing rate. The mode of technological advancement is now shifting from industrial to information & communication. This information age could not have existed without the breakthroughs in the fields of electronics and communication technologies. The development of the transistors and ICs made the existence of personal computers possible. These computers then further gave birth to thousands of new information and software-based technologies. Today, communications technology has advanced a lot and forms the backbone of the modern information society. Technologies like the internet, mobile phones, radio systems, television networks, and satellite phones could not have been possible without modern communication technology.

What is a satellite phone?

A satellite phone or a satphone is a typical mobile phone which makes use of orbital satellites in order to communicate with other phone networks. Unlike cell phones, satellite phones are not dependant on terrestrial cell towers for radio communication. The use of orbital satellites for radio communications makes it possible to use satellite phones from any geographical location on the planet.

The satellite phones in the early 1990s were quite substantial in size and used to feature a retractable antenna. However, today these phones are very similar to regular cell phones and it is hard to distinguish between the two on the basis of appearance.

Figure 1: An Iridium Phone. Source: https://www.bluecosmo.com/satellite-phone-iridium-extreme-complete-kit.html

Application of satellite phones

Since satellite phones have a greater outreach as compared to cell phones, and they work virtually on all geographical locations, hence they are used for many applications where cell phones prove to be inadequate. Some of the applications include:

• Military and defense communications
• Border patrol forces
• Trekking and mountaineering
• Ships and vessels
• Communication in disaster-ridden areas
• Remote hunting and adventure expeditions

Satellites phones are very widely used for military communications. These phones are suitable for military applications because armed forces typically work in remote areas where normal cell phones are either absent or not allowed. Other than armed forces, trekkers and mountaineers largely make use of these phones because there is no cell phone coverage in remote mountains and trails. Ships and cargo vessels also employ satellite phones because terrestrial networks are unavailable in the seas. These types of phones also prove invaluable in disaster-stricken areas where cell phone towers and other infrastructure has been destroyed.

Working of a satellite phone

As the name implies, radio communication in satellite phones happens through the orbital satellites. Based on the type of satellites, there exist two types of satellite networks which are geosynchronous and low earth orbit.

Geosynchronous satellites have the same orbital period as the Earth’s orbital period. As a result of this, these satellites are fixated on a single location on Earth and are present above that same location all the time. Due to this reason, these satellites can cater to a larger surface area of Earth, and 3 to 4 of such satellites can cover the entire globe. Geosynchronous satellites are typically quite huge and powerful. Since these satellites are present at a significantly larger distance from Earth (20,000+ km), therefore transmission delay is quite noticeable in such satellite networks.

The other types of satellites are the low earth orbit satellites. These satellites are not fixated on any single geographical location and orbit at a lower altitude (400 to 700 miles). These satellites orbit around the Earth within 1 or 2 hours. Low earth orbits have smaller transmission delays and the terminals require less power to access the signals. Due to this reason, the phones in these networks tend to be smaller in size as compared to the phones connected to geosynchronous networks.

Figure 2: Working Methodology of a Satellite Phone. Graphics Source: http://hackandtechtown.blogspot.com/2017/08/satellite-phones.html

Difference between cell phone and satellite phone

In the recent past cell phones have become vastly popular and have seen tremendous growth. Although a large segment of the population owns cell phones, they are not adequate in many situations.

The primary difference between cell phones and satellite phones is the transmission network. In the case of cell phones, the transmission network consists of cellular towers. All the cell phone communication is carried through the earth-based cellular towers. Satellite phones, however, do not depend on the ground towers. In case of satellite phones, the signal is sent to the satellite which then sends this signal to the gateway. The gateway then sends the signal to the receiver terminal.

The satellite-based communication makes the satellite phones useable in remote areas where normal phones do not work. This is the biggest advantage of satellite phones.

If we compare the cell phones with the satellite phones in terms of functionality and features, then cell phones are miles ahead. Satellite phones are meant to provide only basic telephony services such as making calls or sending text messages. Cell phone technology, on the other hand, has become very advanced and provides services like video streaming, internet surfing, social media sharing, and navigation.

In terms of utility and applications, cell phones are mostly used for consumer communication whereas satellite phones are more specialized and are used for specific applications such as military, ships, mountaineering and disaster relief. Hence, for normal urban consumers, a satellite phone is not a suitable option. The cities and villages in most of the countries are well covered by cellular towers and cellular telephony is the most convenient and cheapest option for the mass population. Satellite phones are only feasible for users with specialized needs in remote areas.

Advantages and disadvantages of satellite phones

Like all other technologies, satellite phones come with their own set of pros and cons. The user must consider these pros and cons before considering buying a satellite phone. The advantages of satellite phones are as follows:

• Operation in remote areas and seas
• Stronger signal as compared to cell phones
• No need for cellular infrastructure
• Great global connectivity
• Provision for GPS coordinates and navigation
• Water, shock, and dust resistant rugged construction
• Inherently secure and encrypted communication

The disadvantages of satellite phones are as follows:

• Very weak or no signal reception indoors
• Require a clear line of sight to the satellite
• Service interruption due to bad weather
• Bigger and bulkier in size than cell phones
• More expensive service tariffs than cell phones

Costs

When compared to cell phones, satellite phones are more expensive both in terms of hardware as well as tariffs. The main reason behind this is the mass adaption of cell phones which allows the cellular network companies to offer lower rates and still be profitable. Satellite phones, on the other hand, cater to a specific niche which makes them more expensive. Additionally, the satellite infrastructure is more expensive than earth-based cellular towers.

The typical tariff for a satellite phone is anywhere between $0.15 to $2.00 per minute. Making calls to a satellite phone from a traditional network is also quite expensive. Even the satellite calls from one satellite network to another are expensive and can cost up to $15 per minute. All major satellite phone networks offer pre-paid plans ranging from $100 to $5000.

The satellite phone terminal device can typically cost around $1000 with lower-end models starting around $500.

Iridium satellite network

Iridium is a leading company in the field of satellite communications that offers voice and data communication services globally. Iridium operates the world’s largest constellation of commercial satellites. The Iridium constellation consists of 66 cross-linked LEO (low earth orbit) satellites that provide 100% global coverage. The Iridium constellation operates at a height of 476 miles above the earth. This close proximity ensures faster communication, lower transmission delays, and pole to pole coverage. Iridium provides services over land, sea, and air all over earth’s surface including north and south poles. The company has a client base from aviation, maritime, military, and the internet of things sectors.

Thuraya satellite network

Thuraya is another leading satellite telephony company. Thuraya is the satellite service subsidiary of Yahsat which is a global satellite service provider based in UAE. The company provides services to clients from energy, government, media, military, maritime and aviation sectors. The company is able to provide satellite communication services to 2/3^rd of the globe via MSS, quasi global VSAT coverage, and around the globe GSM roaming service.

Figure 3: Iridium has 100% Global Coverage. Photo Source: https://www.groundcontrol.com/Iridium_Coverage_Map.htm

The company provides its services through its three satellites (Yah-1, Yah-2, Yah-3) operating in the Ka-band. In terms of revenue, Thuraya is the 6^th largest satellite communication service provider in the world. The company’s fleet of 5 satellites provides services in 160 countries.

Figure 4: The Iridium Constellation – a robust satellite network. Photo courtesy: https://www.universetoday.com/25447/orbital-spares-iridium-already-replaced-destroyed-satellite/

Conclusion

Satellite phones are the ideal communication systems when secure and reliable communication is required in remote outdoor environments such as sea, land, mountains, and poles. These phones do not require any cellular infrastructure and communicate directly through the low earth orbital satellites. These phones are largely used by aviation, maritime, military, media, and disaster relief organizations. Although more expensive compared to the cell phones, these phones provide uninterrupted service all over the global.