Nothing lasts forever, not even submarine cables. Take the case of TAT-14, the transatlantic cable system that interconnected the USA, the UK, France, the Netherlands, Germany and Denmark. TAT-14 had a ring topology with two transatlantic cables interconnected by cable segments at each end with a total length of 15,428 kilometres.

TAT-14 was commissioned in 2001 and upgraded in 2011 to satisfy the demand for more capacity. But, despite the upgrade, the decision was made to retire TAT-14 with its last traffic carried in 2020.

So, what was the reason for its demise? The answer, as always, is economics. Older systems cost more to maintain while the latest technologies allow far higher capacity and greater reliability. The Havfrue cable system, which replaced TAT-14 in 2020, has ten times the capacity of the older system and links the USA with Ireland, Denmark and Norway.

Recently it was announced that a new IOEMA cable system will complement Havfrue by linking UK, the Netherlands, Germany, Denmark and Norway with connections to the transatlantic links of Havfrue.

Much of TAT-14’s cables has been recovered from the seabed by Subsea Environmental Services which specialises in the recovery and recycling of retired submarine cables. So, the cycle of life continues – out with the old, in with the new.

The PTT online course “Telecommunications networks” introduces the operation and capabilities of the terrestrial, submarine, and satellite links that provide modern communications services.

The technologies that underpin the telecommunications services we all depend on have gone through significant changes in the last few years. The speed of change makes it a challenge for those directly responsible for service provision to stay abreast with new technologies and techniques.
But what of their colleagues who are not directly involved in technology issues? Do they need to keep up to date? For example, do customer service agents and retail sales representatives need to how the services they support or sell are delivered?
Many of us have experienced the frustration of dealing with a service agent who is making every effort to deal with the reported problem but is hampered by a lack of basic knowledge of how the service is provided. And sales representatives need to know the limitations of the service they are selling as well as the benefits.
Arming non-technical personnel with a basic understanding of the underpinning technologies gives them greater confidence in their efforts to address the concerns and requirements of their customers. And that of course leads to greater customer satisfaction.
PTT’s online course “Introduction to telecoms services” is designed for non-technical personnel working in the telecommunications sector. This online course keeps technical detail to the absolute minimum necessary to gain an appreciation of modern telecoms services.
The course, which has a proven track record in training customer support representatives, has recently been updated to include the latest advances in service provision.

In 1945, the science fiction writer Arthur C. Clarke published an article in the U.K. journal Wireless World that laid out the potential of geostationary orbit for satellite communications.

When a satellite orbits the earth at a certain height it appears from the ground to be stationary allowing an aerial to transmit to and receive from the satellite without having to adjust its orientation. The satellite can then act as a radio relay station in space allowing international communications.

The first active communications satellite, Telstar, was launched in 1962 and relayed the first publicly available live transatlantic television broadcast between North America and Europe.
Telstar was launched into a medium earth orbit (well below geostationary) so the large earth station aerials had to track its path with communications lasting for just 30 minutes.

The first geostationary orbit (GEO) satellite to provide commercial services was launched in April 1965. Intelsat1 (also known as “Early Bird”) provided uninterrupted contact between Europe and North America for television, telephone, and fax transmissions.

Until the expansion of the web of optical fibre submarine cables, GEO satellites using earth stations with large dish antennae relayed most international telephone calls between continents.
In 2003, Eutelsat’s eBird GEO satellite provided Internet access for those in remote areas including ships at speeds comparable to that provided by ADSL over telephone lines, the predominant broadband service at the time.

Advances in technology and the use of higher radio frequencies led to higher speeds in later generations of GEO satellite with access to broadband services provided by very small aperture terminals (VSAT). However, the long distances that signals have to travel leads to long delays between sending and receiving signals.

Then came low earth orbit satellites. As the name suggests, these orbit at a much lower height allowing even faster broadband speeds and much lower delay. However, as LEO satellites move across the sky, a constellation of satellites are required for an uninterrupted service with small, electronically steerable antennae following the satellites’ movement.

There are now over 7500 communications satellites orbiting the earth with the majority being LEO. LEO satellite services have the potential to eliminate Internet access dead zones around the world.

Other uses include providing inflight connectivity for aeroplane passengers and providing backhaul connections between mobile operators’ networks and their base stations in remote areas.
Providing connections to the Internet of Things (IoT) including weather monitoring devices is another possibility.

But perhaps the biggest impact on telecommunications services will be so-called direct to device (D2D) applications where the satellite transceiver is built into devices such as conventional mobile phones. Then ubiquitous access to 4G or 5G mobile services will be possible even when out of range of terrestrial base stations.
SpaceX recently launched six D2D satellites with others planned to provide a constellation of 21 D2D satellites.

You can learn more about satellite communications from the PTT online course “Wireless communications“.