Introduction

As everyone knows, communication - and developing ways to improve it - between people has always been, is, and very likely will remain being one of the most important fields in the development of technology of the civilized world. The purpose of this document is to clarify the what's, why's and how's of the development of telecommunication technology from ancient times to foreseeable future.

Early history of telecommunications

Even the most primitive of human cultures in ancient history developed some ways to communicate with each other, from guttural sounds and facial expressions to body moves and gestures. In addition, there has always been a need to communicate with others across an arbitrary distance, for instructions and orders while hunting etc.

At first, the means for long-distance communication were very crude and inefficient - also unreliable - but, they worked. There were three main means used:

  • noise (megaphones, church bells, cannons etc.)
  • optical effects (heliographs, watch towers and smoke signals, flashlights and semaphores)
  • physical delivery (runners, horses, stage coaches, carrier pigeons, later on trains and other motor vehicles)

The first big breakthrough

Telegraph, invented in 1838, was taken into wide use six years later, in 1844, when Samuel F.B. Morse introduced his revolutionary new language - the Morse code. During the same year, the very first long-distance telegraph message was sent between Baltimore and Washington. What made telegraph such breakthrough was the incredible speed, at which data could be transmitted; nearly at the speed of light.

Here is a small comparison chart, to compare the various historical telecommunication methods in a modern way:


                                                Distance       Bandwidth-
                                                between        distance
Method          Data rate        Msg speed      "repeaters"    product
-----------------------------------------------------------------------------

Carrier pigeon  ~10 kbit/pigeon  70 km/h        700 km         150 kbit-m/sec

Megaphone       100 bits/sec     1000 km/h      2 km           30 bit-km/sec
                                 (but many
                                 repeaters)

Train           Very high/train  70 km/h        Virtually      very high
                                                zero

Telegraph       100 bits/sec     Very high      20 km          1 kbit-km/sec

With short messages, telegraph was far superior compared to any of the earlier methods, due to its very high transmission speed. The intrinsic error rate of the telegraph was very low and, in case of errors, re-transmission was easy and quick. Also, telegraph was relatively cheap, and it was not man-power intensive.

Carrier pigeon turned out to be rather efficient as a telecommunication method by its calculational bandwidth-distance product (although that does not tell much, since the intrinsic error rate is not taken into account). Carrier pigeon media was relatively fast, it could deliver a relatively large amount of data at once and the intrinsic error rate is virtually zero (all errors made were transmission-media independent human errors).

Megaphone was a very unreliable transmission media, mainly due to its very limited range of about a mile or two, if the weather was good and there was little or no wind. Thus, it was very man-power intensive, if the distance between the endpoints was high. Transmission speed of the megaphone was relatively high - the speed of sound or, 1000 km/h (600 mph) but, the intrinsic error rate of the megaphone is also high and the amount of data transmitted at once (or, the bandwidth of the megaphone-media) was only about 30 bit-km/sec.

Train turned out to be another relatively good transmission media, and not the least because in addition to the very high data transmission capacity, it could also carry nearly any kind of metadata (food, people, tools etc.) with it. It is impossible to give any unambiguous transmission speed for the train transmission-media, since it has changed a lot due to development and, is dependent on many external factors. The amount of data a single train can carry is practically infinite, the amount of repeaters is virtually zero, in addition to which, train is intrinsically equally error-free transmission media as the carrier pigeon.

As a transmission media, however, telegraph was - and still is - unequivocally the biggest breakthrough of all times - all concurrent transmission medias and those in foreseeable future are, and will (at a very high probability), be based on it.

Telephone, radio, satellites and fiber optic cables

Telephone was a rather logical next step after the telegraph. The two have many similarities, including low intrinsic error rate and low bandwidth (for speech, data transfer rates are considerably higher). Although the first telephone message ever was sent as early as 1876 (7 words, from one room to another) and, by 1890, many cities had primitive telephone systems, the first trans-Atlantic phonecable wasn't installed until in 1959. The first official trans-Atlantic message (90 words) took 67 minutes to cross the ocean. As of now, telephone is, by far, the most popular transmission media used.

The first trans-Atlantic wireless (radio) transmission was made in 1901; the letter "S" was sent in Morse code between the USA and UK. At first, radio was a very expensive transmission media to use, its quality was very poor and the availability of radio links was very low. In short, radio was a very poor transmission media for critical data in its first years. It took another 10 years to establish worldwide wireless telegraph links. By 1920, all major countries had a small number of High Frequency radio stations for long-distance telephony - an estimated 100 such stations worldwide.

In 1956 more phonecables were installed across the Atlantic, which added the capacity to 36 simultaneous telephone channels between Europe and North-America. This was such an increase it was estimated to be sufficient for at least the next 15 years. Thus, the expensive and unreliable radio links were closed. Only a few months later, however, the radio links had to be reopened due to high demand. This, in part, triggered and encouraged the development of a reliable wireless transmission media. A demand, that was met in 1965, as the first commercial geostationary communications satellite Intelsat 1 (Early Bird), with 240 phone circuits, was launched. Some subsequent satellites include Intelsat V (1980, 12500 phone circuits) and, Intelsat VI (1989, 33000 phone circuits).

The first trans-Atlantic fiber optic was laid in 1988. It was called TAT-8, and it carried 40000 telephone circuits. Some subsequent fibre optic cables include TAT-9 (1992, 80000 telephone circuits) and TAT-12 (1996, 300000 telephone circuits). Currently, there are 10 such cables in service and, another 10 under construction or planned.

Data networking

The main differences between telecommunications (referring mainly to voice transmission) and data networking (referring mainly to data transmission) are that telecommunication medias are mainly circuit switched and the industry conservative, while data networking medias are mainly packet switched and the industry dynamic.

There is a strong - and accelerating - trend for the traditional telecommunications services to be provided using data networking technologies. There is also a strong - and accelerating - trend for the data networking services to provide the same quality of service as the traditional telecommunications services.

Conclusion: the two industries are consolidating. According to some predictions, this consolidation will be complete, and the industries indistinguishable by the year 2010 (prediction made by the course lecturer Rob Parker CERN-IT).


This text is a part of a course-study in telecommunications technology.

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