2. The Communication Backbone

In 1950, long-distance wireless communication was achievable with short wave radio. The ability of the earth's ionosphere to reflect radio waves allowed these signals to travel particularly far without the requirement for too powerful a transmitter. Medium and long wave transmissions also benefitted to a lesser extent from this effect, particularly after dark when the reduced noise from solar transmission allowed the signal to be picked out more easily from further afar. Wireless radio broadcasting allowed the transmission of news and entertainment programmes worldwide, but there had to be conventions on the allocation of a particular wavelength to a station, so that two stations would not interfere with their transmissions. At least that was he principle.

Limited international telephone connections were possible, over undersea cables. These were expensive to maintain and limited in the volume of traffic, and thus way beyond the price the casual user would pay, so were largely only used by official callers. In 1945, Arthur C. Clarke published an article in Wireless World proposing the use of satellites in "geostationary orbit" as a means of establishing worldwide radio coverage. As a satellite orbits further and further away from the earth above the equator its period of orbit gets longer and longer until at a height of 36,000 km its period is 24 hours, so it remains at a constant location in the sky as the earth rotates. With three satellites so positioned, they can remain in uninterrupted contact with each other, and one can be pointed to from any habitable latitude. At the time, the ability to launch satellites into orbit was out of the question, but the race was clearly on between the USA and the Soviet Union following the invention of relatively reliable high altitude missiles by Werner von Braun and his team in Nazi Germany during the second world war.

The communication technology was available however. The transistor had been invented in 1947, which allowed the satellite designers to replace the thermionic valves used in normal radio transmitters and receivers that would have surely made a ground-launched satellite too fragile and unreliable and its energy requirements too high. The only "tube" that would need to be on board was the transponder that would transmit the broadcast. In due course therefore communication satellites were launched into orbit. However the thrust and skills needed to get to geostationary orbit was not available initially, so satellites were only useful for the limited periods when they were above the horizon, and thus able to be used for communication between two points.

In 1962 Telstar-1 was launched by the USA and was used for transatlantic communication for about thirty minutes every two and a half hours. But progress in rocket payload capability was such that just two years later the USA could launch Syncom-3 into geostationary orbit over the Pacific Ocean, enabling particularly viewers in the USA to witness the 1964 Tokyo Olympics in real time. This was perhaps the first time the consumer was made aware of "latency" - the fact that it took much longer for audio to pass to and from the satellite 36,000 km away and to be answered again with a satellite bounce, than it took for a conversation by terrestrial undersea cable. Conversations could only be conducted with uncomfortable pauses between responses. By 1967 it was possible to have the first worldwide broadcast the technology finally allowed, involving three satellites positioned around the equator. This was "Our World" which was viewable simultaneously in Europe, America, Australasia and Japan, and was memorable for the inclusion of a segment in which the Beatles first performed "All You Need Is Love".

Telephony in the 1950s for the public was relatively primitive. Only local telephones could be dialed by the user, and any long-distance or international calls had to be routed via a human operator, to maximise the use of the available copper wire network. It was also customary for users to be advised of the likely cost of their long-distance calls before they made them, as they could be quite expensive. The telephone itself had remained unchanged in design since the 1930s with a loud ringing doorbell-like sound, and was made of black bakelite, an early hard plastic, and featured a dial with the digits 0 to 9, sometimes mapped to letters of the alphabet, for ease of remembering the local code of the exchange. For instance my phone number was Livingstone 1854. The first three letters of Livingstone corresponded to 548 on the phone dial, making the exchange code easier to remember, and in those days one used to answer the call with the acronym and number to reassure the caller they had the correct connection. This system is still in use in the USA, where companies can sometimes choose their number to translate into a meaningful word appropriate for their business.

In the 1950s, countries were modernising their telephone systems and automating the exchanges, beginning the process of replacing the mechanical relays, which routed the calls, with steady state electrical circuits based on the transistor. This allowed, for instance, the UK to allow national dialling without the operator from 1958, prepending an area code for cities and their surroundings, and international dialling (prepending also a country code) without operator intervention from 1963, just as the extra bandwidth allowed by geostationary satellites was becoming available. However the latency problem mentioned earlier tended to increase demand for greater bandwidth on terrestrial cable connections.

In 1968, the UK and others moved on from the traditional phone design to a more modern look. In the UK it was the "Trimphone" - a slimline plastic telephone with thin handset and a base unit no wider than the dial, and a ring tone which was a cheery electronic trill, which was retained until superseded by a button version in 1980. Initial colours were two-tone green and brown, but later brighter colours were added to the range. Public telephones were widely available in the 1950s and were also of the traditional black bakelite, but were gradually modernised during the 1960s to reflect more modern colours and to be more thief- and vandal-proof.

With the increasing availability of long-distance communication channels either by satellite or cable, there was an obvious opportunity for their use for transmitting data from place to place. One way of doing that would be to establish a connection, and then transmit the data. The problem was that connections could be unreliable, and if a connection was broken mid-transfer, the transfer would have to start again from the beginning when it was re-established. An alternative - "packet switching" - was proposed in 1965 by engineers at RCA in the USA and the GPO in the UK, whereby the message would be split into fixed length blocks and transmitted with a header identifying the document and the sequence number of the block within it, so that it could be checked by the recipient and reassembled and any missing parts requested to be retransmitted.

This workaround initially to outwit unreliability in a communication network was exactly the solution the military, particularly in the USA, had been looking for to make their communications systems less vulnerable to attack. By spreading any transmission of data into packets sent between computers over several parallel paths through the network, but making only the end points responsible for checking the completeness of the whole file, the overall resilience of the transmission could be almost guaranteed also when some intermediate nodes failed or became unavailable. In parallel to defence developments, an initial system using this scheme, the ARPANET, was established in the academic realm in 1969 between UCLA, SRI International and UC Santa Barbara, and expanded to 15 sites by 1971. Meanwhile also in UK and Norwegian academe similar networks were being established between institutions, and these were also joined to ARPANET after basic TCP/IP (transmission control protocol/internet protocol) protocols were established to fix common standards on how the computers on the network could be addressed and would communicate.

This agreement culminated in the decision to adopt Internet Protocol Version 4 in 1981, which essentially established the form of internet connectivity the basic internet has today with computers having four byte addresses converted to meaningful names via domain name servers (DNS). These protocols govern the way files can be transferred from place to place, allowing various applications to be run, such as to directly message another user, to send a delayed message - electronic mail ("email"), to run remote operations on other computers on the network, to post information to remote sites (as in newsgroups or bulletin boards), and in general to interrogate to find out information about the various network nodes.

One additional difficulty of transmission of data across a shared network of computers out of the control of individual users at each end is to maintain privacy of that information. It was therefore important that in 1977 Ron Rivest, Adi Shamir and Leonard Adleman invented RSA encryption, a form of public key encryption. The idea behind this is that a public key is published and anyone can use that key to encrypt their message. They send their message to the recipient who is the only one to have the private key which they can then use to decode the message. To make this watertight, the keys have to be sufficiently long or the message can be cracked in principle in a finite time. Nowadays this means that the keys have to be 2 kB in length, given today's computing ability. The only way such a system can be outwitted is if a quantum computer is used for the solution, but they currently do not have the capability, so this process is safe, for now.

Despite and because of all the above developments, transmission of data was nevertheless becoming increasingly limited by the ability of copper cables to carry digital signals. What was needed was a fundamentally new approach. Two inventions in the early 1960s would start that development: the laser and the light emitting diode (LED). The laser for the first time produced a beam of coherent light - light where all the wave packets (photons) were "in phase" with each other, meaning that the light beam did not spread out with distance. This for instance allowed a mirror placed on the moon's surface by astronauts in the 1970s to be used to reflect a laser shone from the earth, thereby measuring the earth-moon distance for the first time to millimetre accuracy. The LED on the other hand produced incoherent light but in a very efficient and controllable way and at a small scale that could be integrated well into electronic circuits. Meanwhile the ability of a glass filament to transmit light long distances by internal reflection off the sides of the fibre had been known for some time, and ways of elongating the transmission distance by reducing impurities were being developed. Combining the two technologies produced some rather pretty ornaments to win at the fairground but it was soon realised that this also allowed digital signals to be transmitted long distances by fibre optic cable (a bundle of filaments to allow parallel transmissions).

By 1977 the first digitised telephone conversations were transmitted over 6 km at 6 Mbit/s over a fibre optic cable in California. Increasingly thereafter such cables were used for data transmission, using lasers, now miniaturised into a diode, for long distances, and LEDs as the light source for short distances. Key to this was the electronics at the cable joints, based on photodiodes, which convert light to electricity using the photoelectric effect. In the 2020s fibre-optic cables are replacing copper telephone cables right into people's homes, allowing data transmission of at least 1 Gbit/s to the user. This means increasingly the analogue telephone connections developed for landlines over the last century powered by the local exchange are being replaced by digital telephone transmissions sent over the internet and powered by the user. This, however, introduces a weakness into the system, due to the lack of emergency service connection during a power cut.

Fortunately, telephony has also meanwhile moved away from being dependent on landlines. With the invention of communication satellites it became possible to make telephone calls using them. For geostationary satellites these suffered from the problem of latency mentioned earlier, and required carrying a dish or array receiver, meaning they had rather a niche market. The alternative was to develop a network of short range radio cells covering populated areas. Each cell would handle callers within its area, and the cell receiver would connect to the ground-based telephone network. If users moved outside the range of one cell the call would be passed and routed automatically through the next cell, making the phone effectively mobile.

Initially such telephones were heavy and power-consuming, and only really suitable for connection between vehicles. The first truly portable mobile phone was the Motorola DynaTac 8000X, which in 1983 made a call from the USA to Germany using phone cells. This phone, looking like a brick, weighed 3/4 of a kilo, and allowed a call time of 30 minutes before a 10 hour recharge. By 1992 though, analogue mobile phones had moved on to the first true pocket phone, the Nokia 101, which weighed only 1/4 of a kilo, and effectively established Nokia as the leading supplier of mobile phones for the coming decade, until the new "smartphones" began to dilute its market. By now the phones were using the more secure digital transmission, which also allowed more users per cell.

The "smart" aspects involved incorporating various "apps" - applications that allowed the user to combine the features of a personal digital assistant, handling appointments and address book, as well as allowing limited web browsing (see later) as well as mobile telephony and paging (equivalent today to messaging). This period is perhaps best exemplified by the Blackberry, first introduced in 2000, which became the market leader, but using older and tried technology (e.g. a mechanical keyboard). Once the iPhone and its operating system iOS, were introduced in 2007, at the same time as Google's Android operating system for competing manufacturers, they increasingly took over the market and now dominate. In 2022 worldwide iOS users represent 30% of all smartphone users, and Android 70%. Despite Apple's lower market share, the innovation, capability and reliability of its device and operating system has from the outset in 2007 made it the trend-setter in the market.

One of the most influential and widely used smartphone apps is "Whatsapp" - available both on iOS and Android since 2009. This allows instant messaging to other users or groups of users, over the internet or cellphone network. It enables groups of users to organise themselves e.g. to meet, or more importantly to act together to do something, and has thus enabled huge changes in society due to concerted action. There are more recent alternatives, such as Telegram, Signal or iMessage (Messages) which offer additional features. The last version of Whatsapp, and the alternatives, use end-to-end encryption of the messages, ensuring complete user privacy even from the service provider, but raising serious difficulties for law enforcement.