Submarine Networks: An Evolutionary Change – Part 1
As published in the July Issue of SubTel Forum Magazine
By Derek Cassidy
July 29, 2022
Communications is a very powerful and strong word, and it evolves many things within people. From the earliest societies to the present day, it has developed into an umbrella word enveloping many different forms of communication from the spoken and written form to the mass interactions we have with people and machines, across the globe. The development of communications can be categorised into different revolutionary or evolutionary periods, depending on which way you look at it. These different periods in human history coincided with or influenced the evolution of human society, pushing it further along the path of development and enlightenment. Each period being more transformative that the preceding period. But also, being the launchpad for and contributing to next evolutionary stage in the development of communication. However, none were more influential or decisive than the other as each evolutionary communication change brought with it, its own dramatic influences.
However, there is one evolutionary change in communication that did lead to a substantial change in how people communicated and interacted. This change in communication direction can be identified as the internet age. The age of mass communication where the many actors could interact with this new way to communicate and help the evolutionary process. Over the last thirty odd years the development of the internet has been always in a fast state of change compared to the previous communication eras long gone.
The term internet, which is used to describe an international set of interconnected networks that help form a single united network sharing an agreed communication protocol, is itself a description of what we have today. Networks spanning the globe interconnecting with other international, national, and local networks forming the internet we know today.
However, since the emergence of Covid-19 and its rampant surge around the world, the need to lockdown society was required to try and develop some sort of defence against this pandemic. But in doing so the economy and society itself needed some sort of coping mechanism. It came in the form of broadband connectivity. The sudden move away from the office and the requirement to setup new working stations in domestic settings created a huge demand on the existing broadband infrastructure. This demand was so sudden that many network operators had to hasten plans to increase their network capacity overnight.
This was only possible because of two separate factors that both worked together to deliver the backbone of this new high-capacity bandwidth; optical channel bandwidth increase and submarine cable infrastructure.
It is easy to see why the optical channel increasing from 10Gb in the early 2000’s to the emergence of the 100Gb optical channel in 2010 and re-engineered in 2013 had a great effect on the capacity of optical networks. This increase in capacity along with the introduction of 400Gb optical channels, all agreed and standardised by the IEEE, would be the backbone of the network growth today. The ability to pack as much data into an optical channel and then getting as many of these optical channels onto a single fibre with the aid of dense wave division multiplexing (DWDM) and Flexgrid technology truly helped the scaling upwards the capacity on optical terrestrial and submarine cable systems. These systems were helped when using coherent technology which was a true driver behind the explosion in broadband connectivity and delivery across the globe over the last few years. Without the internet the past two years under lockdown would have been a disaster for the international global economy.
However, as the internet is a set of interconnected networks spanning the globe, it was the submarine cable that helped deliver this connectivity. The submarine cable itself, even though only a physical medium, needed the technical infrastructure behind it to be capable of carrying all this traffic. But have you ever wondered what life would be like without the existence of submarine cable connectivity? The question would be, what type of communication system we would have and would have society have developed as it has, along the communication path without the existence of the undersea umbilical cord? To fully understand this question, we must first look at the evolution of the misunderstood submarine cable.
From the early 1840s the idea that telegraph cable could be laid across rivers was first investigated by O’Shaughnessy in India and then further investigated by Morse, in the US and the Siemens Bros in Prussia. However, it was only possible by the invention of the Gutta Percha extrusion machine that enabled telegraph wire to be extruded over copper wires efficiently and quickly that enabled long lengths, in Kms, to be successfully insulated in a manner that would enable the production of the first submarine cables. Although this invention was in the era of the telegraph and preceded the telephone by about 30 years, the ability to send messages as electrical signal across large distances was seen as the next evolutionary stage in the development of communication.
Henry Bewley and his Gutta Percha extrusion machine changed the world of Telegraphy. The ability to insulate long lengths of telegraph wire enabled the installation of telegraph systems under ground and the most important outcome was the installation of telegraph system under water. With the establishment of the Gutta Percha Company in 1848 and the enterprise set up by the Brett Brothers, the first insulated submarine cable was laid between Dover and Calais in 1850. It did not last long, but it did prove that insulated telegraph wire could work under water. However, as the cable was not armoured, as seen in figure 2 below, the likelihood of damage was high and in the case of the 1850 cable, it was the first reported incident involving damage caused by fishing. In future all submarine cables would be armoured so as to offer some protection on the seabed.
The core design of the 1850 cable was also a single strand of copper, the next submarine cable, the 1851 St. Margaret’s Bay, England to Sangatte, France had an updated design where it used four separate telegraph core conductors insulated with Gutta-Percha and armoured for protection, see figure 3. This design was first of many that would lead to the development of submarine cable technology.
Soon submarine cables were being laid across the European continent and connecting telegraph stations across seas such as the North Sea and the Irish Sea. A drive to connect the different countries states and colonies was seen in British eyes as “Britain Connecting the Empire.” In 1852 the first submarine cable laid between Britain and Ireland was laid between Holyhead and Howth, see figure 4. Although six more cables were to be laid across these sections in the coming years, this cable was a failure due to the design and the little-known knowledge of laying a submarine cable over this large distance compared to the original cable laid between Dover and Calais, a mere one third the distance of this new submarine cable. The technology needed to be improved upon to achieve communications under water over this and longer distances.
As time progressed and new cable designs were investigated the second successful submarine cable was laid between Donaghadee, in Ireland and Portpatrick, Scotland. This cable, being the third such attempt by two different companies successfully proved that by careful planning, route designation, submarine cable design that it was possible to successfully lay a telegraph submarine cable across the sea. Now that the seas, rivers and lakes were seen as an obstacle that could be overcome, the next horizon was the oceanic crossings that would really mean a connected telegraph world.
Telegraph communication, on land and across continents, in the 1850s was interpreted as a given with regards to communication and its connectivity as the telegraphy era took hold. Britain was looking eastwards and looking to connect India, its Crown Jewel. However, this could only be done by short submarine cable connections and long-distance overland telegraph systems. However not all of these telegraph networks would be in British territory and so security of these networks was at the behest of the country or empire the networks crossed.
However, there were signs of tension, that can be seen in today’s society. War broke out in Crimea in 1853 between Russia and the Ottoman Empire with Britain, France and Piedmont on the side of the Ottomans. It was started dues to religious tension and soon escalated into a war firstly between Russia and the Turks but was soon blown into a full-scale conflict. It was the first real conflict that used telegraphy as a means of communications. However, the Russian Telegraph Network was far more expansive compared to the British, French or Ottoman telegraph network, especially in this part of the world. An example of this is the reports from the Crimea war which were reaching the public, in Russia within two to three days while the British and French were slow in receiving strategic military information. Information from the battlefield along with the public information bulletins were taking in excess of three weeks to reach London. News from New York was getting to London quicker, yet the Crimea was closer and had a direct land route albeit a 23-mile submarine crossing that would utilise the St. Margaret’s Bay, England to Sangatte, France (1851 Dover to Calais) submarine cable. The allies knew that something had to be done. As the Russian Empire had control over the information and what was being widely published, promoted and disseminated within general circulation as the Russian telegraph network and system of communication was quite extensive. The allies (Britain and France) had to rely on steam ship between Sevastopol to Constanta or Varna and then by cross country rider to Bucharest and Sofia before any telegraph message could be sent back to Paris or London. As Russian army could receive information and orders via telegraph in a matter of days and even hours but the Allies had to wait weeks before any information was received or successfully delivered to its destination. They only way to overcome this delay in communications was to lay a submarine cable across the Black Sea and connect Sevastopol and Varna in Bulgaria. This new submarine cable along with the installation of a new telegraph network connecting Varna with Sofia and Bucharest reduced the delay in communication from weeks to just days.
However, this was 1855 and the war was already raging for well over a year. This was also the first war that telegraph, its equipment and backup resources had people assigned to work and operate as a dedicated unit. This led to the formation of the Signalling Battalions within an army’s structure. In this instance the ability to connect to a telegraph submarine cable was of utmost importance for the fast delivery of communications and specific battle orders etc. But it was on this battle front the term War Correspondent was first coined when William Howard Russell, an Irish Reporter sent to the Crimea by The Times Newspaper to report on the war. Russel was to write up and to report on the daily activities and overall information on the war as it was happening. He had to be report in a positive manner so as to deride any negative attention that would be faced by the Allied Governments with regards to the war. This first reported use of propaganda used by a state across a telegraph network. Even though his reports took a few weeks to get back to London, the British Public took a deep interest in the war and soon the British Government and the Ministry of Defence were facing a backlash due to the very real description of the war by Russell as he refused to follow the government dictated rules applied to Newspapers, but he was a true journalist who instead reported on and wrote exactly what he saw. Again, another first for true reporting from a conflict zone only possible by telegraph with the aid of submarine telegraph cables.
However, when the submarine cable was laid his reports were received in London within days and due to the capability of submarine cable connectivity, the “nearly” up to date reports were getting the attention from most if not all levels of Society in Britain, creating an even bigger headache for the authorities.
The need to share information and gather news for the general public was now seen as a main contributor to telegraph communication and the general public seen as the consumer. Up until now submarine cable connectivity and usage was really only available, due to costs etc. to Governments, Military, large business with some use by distributors of information i.e., Newspapers etc.
Reuters, established in 1851 in German and set up an office in London, was established with the main purpose of using the telegraph, as a means, to getting financial and business news distributed to those who required this information. Soon Reuters established itself as the main supplier of this information and also as a trusted one due to the speed in which it could disseminate the information across the telegraph wires. It was the first company who saw the telegraph network as a tool to successfully grow their business and for an information company to establish itself as content provider and consumer of news and information.
As the development of the telegraph took hold and the networks began to spread out across the continents the need to connect these continents was seen as an obstacle needed to be overcome but the tools were not available at the time. However, between the years 1857 and 1866 there was a drive to overcome this restriction in long distance underwater telegraphy that could span the oceans. Cyrus Field along with Charles T Bright, C S Varley, William Thompson, and many others worked on and contributed to all or some of the many attempts to cross the Atlantic with a telegraph submarine cable. Four of these attempts failed due to cable construction, defects during storage contributing to electrical shorting or just bad luck with the cable paying out machines. These attempts have been well recorded, publicised and spoken about however, the fifth attempt in 1866 proved successful as did the recovery of the 1865 trans-Atlantic cable. Within two months between July and September the Atlantic was now crossed by two submarine telegraph cables.
However, as these expeditions to lay a submarine cable across the Atlantic had their technology issues with regards to cable ships, cable paying out machines, route design and splicing techniques, the submarine cables associated with these attempts had changed in design over these years. The 1857 cable had a central core of seven stranded copper conductors, as had the 1865 and 1866 cables. However, the 1857 cable had a different armouring design compared to the other two cables. The Deepsea section of the 1857 cable had an armour that was eighteen different sets of seven steel strands in a design just like the conductor. However, as this armouring was designed by Isambard Kingdom Brunel, it was thought that the strength would be a strong as the steel stranded wire that was being introduced as wire rope. However, this was the design flaw, wire rope is compacted together and helps form a solid structure with many strands, the 1857 cable could not offer this same type of alignment for the reason the Gutta Percha, hemp filling yarn and the electrical conductor restricted the armouring forming a steel wire construction. The armour lacked the tensile strength it needed to be able to sustain the weight of the cable as it was suspended in the sea under the cable ship. The eighteen different sets of armouring strands acted like eighteen different sets of wire rope and each in turn tried to sustain the weight of the suspended cable being paid out behind the ship. They did not act in unison and together as a wire rope of may wire bundles is designed to do and so it lacked the much important tensile tolerance to keep a cable in suspension. The 1865 and 1866 trans-Atlantic cable seep sea sections had armouring that was constructed of a single steel wire with a larger diameter and with between 11 and 14 wires forming the outside armour. This design, although not new and used on other cables, was seen as the best option to protect the cable from reaching its breaking strain and causing the cable to break or snap under its own weight, while in free suspension. The shore ends on the three different cables also differed with the 1857 and 1866 cable using the single larger diameter steel wire and wrapped around the cable in the same format of between nine and twelve strands making up the shore-end armouring, which had to particularly strong to sustain and protect the cable from anchor, fishing and sea bottom movement and chaffing off rocks. However, the 1865 cable had a different shore-end design which was also used in the 1870 India submarine telegraph cable. The design was three strands making up a combined cross-sectional area that was equal to two single stands used on the other cables. There were twelve of these making up the shore end armour. This design did not suffer from issues associated with overreaching the tensile tolerance with regards to cable weight as it was not used in deep water. However, this design would have an issue with being damaged from fishing as the three stranded wire could unravel and cause the cable to become earthed if it pierced the insulation or if more than the half the wires unravelled it could kink the cable causing breakage or earthing issues.
The telegraph transmission technology also changed with the introduction of Thompsons Galvanometer that could detect very low voltages to the rate at which words could be transmitted. In 1858 when the first trans-Atlantic was connected it had a rate of between two and four words a minute. However, the 1866 trans-Atlantic telegraph cable could achieve eight words a minute, and the ability to transmit more words a minute was always being investigate. The increase word could mean that more telegraph messages could be sent creating a bigger revenue stream for the operators.
But, the author, has subsequently discovered that many of the displayed samples of the 1865 cable on view are not in fact the 1865 cable but a terrestrial telegraph cable laid across Valentia Island. This cable had a total of eight copper conductors, in the centre there are two copper conductors and on the outer part of the gutta percha insulation there are six more conductors. The outer armouring is the same design as the 1865 cable. So, in effect this cable was either laid in 1865 or later in 1869-70. No matter when it was laid the fact that it had multiple conductors was proof that future proofing the existing telegraph infrastructure was considered and put into practice, something that had not been considered before then. Planning for future telecom, albeit telegraph, connectivity had now found a footing and foundation within the communication world.
With the successful completion and connection of the 1866 and then the subsequent delivery of the 1865 cable the ability to communicate between London and New York and receive a reply with a few hours was a vast difference to the four weeks in which a reply, at its fasted delivery route across the vast Atlantic, could possibly be expected between the two cities before the cables were laid. However, these two cables also had another effect on society, the economy, financial and stock markets. These two cables meant that the two stock and financial markets of London and New York were now connected meant that they could now communicate more efficiently with hours rather than weeks. There was also a big change in the Cotton markets as the cotton producers could now find a wider audience for their produce and buyers also had a bigger selection of sellers that now spanned the known globe from America to Asia the cost of cotton was now subject to stock prices that could be speculated upon thanks to the trans-Atlantic cables.
With the successful completion of the 1866 trans-atlantic submarine telegraph cable the telegraph world had now overcome its biggest obstacle yet. That is to build a long distance underwater telegraph network that would connect the world. The route to India through British controlled territory and across oceans to increase speed and avoid contected and uncontrolled areas was now a possibility. The age of the Victorian Internet had started and it had its international foundation in Valentia Island. The telegraph, along side the Atlantic submarine cable and other submarine telegraph cables established the true national and international and even intercontinental telegraph network. It found its way into society as a means of communications and opened up the world to the era of information.
About the Author
Derek Cassidy is doing a PhD in the field of Optical Engineering; Waveguide creation and Wavelength manipulation with UCD, Dublin. He is a Chartered Engineer with the IET and Past-Chair of IET Ireland. He is Chairman of the Irish Communications Research Group. He is also currently researching the Communication History of Ireland. He is a member of SPIE, OSA, IEEE and Engineers Ireland. He has patents in the area of Mechanical Engineering and author of over 30 papers on Optical Engineering. He has been working in the telecommunications industry for over 27 years. Derek holds the following Degrees; BSc (Physics/Optical Engineering), BSc (Engineering Design), BEng (Structural/Mechanical Engineering), MEng (Structural, Mechanical, and Forensic Engineering) and MSc (Optical Engineering).