| The history of the computer inevitably includes | | | | into GCA or Ground Controlled Approach. |
| the development of electronics, we look at the | | | | Shipping - radar equipped vessels could track |
| explosive (!) growth of electronics in the late | | | | other vessels in darkness or fog, whether |
| 1930s and early 1940s. | | | | peacefully or aggressively. |
| If anything could be said in favor of war, it may | | | | Many other sytems were developed or initiated in |
| be that it speeds up the development of | | | | that 6 year period. Knowledge of electronics, and |
| technology. Of course much of that technology is | | | | what it could be used for vastly increased. In |
| employed in killing people and destroying | | | | parallel with the development of radar, other fields |
| infrastructure, but there are also things which | | | | of electronics were also advancing, under |
| could be considered beneficial. | | | | pressure from the requirement to improve the |
| Electronics was around in the early part of the | | | | technology. |
| 20th Century, wireless, or radio, was in its infancy | | | | Long range guns on ships or in the field needed to |
| at the time of the first world war. Radio | | | | be aimed accurately. The calculations required in |
| broadcasting came into prominence in the '20s and | | | | ballistics to aim a gun so that you can hit the |
| 30's, Television started in the '30's. | | | | target, or aim a V2 rocket so that it hits London |
| The second world war, from 1939 in Europe, and | | | | from continental Europe, are phenomenal. |
| a couple of years later involving the USA, ended | | | | This, then was the scene at the end of the war. |
| in 1945. Radar (Radio Aid To Detection And | | | | We knew how to tackle large calculations with |
| Ranging) was developed from early experiments, | | | | speed, and we had developed a new concept in |
| just prior to the war, in Britain and Germany. | | | | electronics, Pulse Technology. This is so called |
| There was rapid development in the field, and, by | | | | because radar uses short pulses of high energy, |
| the end of the war, Radar was being used in | | | | for two main reasons. |
| several fields. | | | | 1. The pulses can be coded. For example, in the |
| Aircraft Navigation - Using ground transmitters in | | | | Navigation example we looked at, 3 ground |
| sets of 3, widely spaced, to give an aircraft using | | | | stations transmit a signal whose source needs to |
| a receiver a method of pinpointing its position. This | | | | be identified. One transmitter could transmit a |
| is a similar system to that used in gps today, | | | | series of single pulses spaced say 10 milliseconds. |
| substituting satellites for the ground stations. | | | | A second could transmit a pair of pulses at 10 |
| Targeting - A beam was transmitted from a | | | | millisecond spacing, and the third 3 pulses. A chart |
| Radar station in England so that it intercepted a | | | | would tell the navigator where the pulse sets |
| target in Germany. An aircraft could fly along the | | | | were transmitted from, and the distances |
| beam, guided by signals, dots or dashes, if it | | | | obtained from the radar set used to locate the |
| strayed off the beam, left or right. Known as | | | | position on the chart. |
| flying on the beam. | | | | 2. The power, or strength, of the signal. A |
| Interception - a series of ground stations around | | | | continuous radio signal, like a radio broadcast, |
| the South-East coast of England, feeding into a | | | | takes a given amount of power. However, a 1 |
| central control room, where their tracks could be | | | | millisecond pulse every 10 milliseconds, uses only |
| displayed, significantly assisted in the Battle of | | | | one tenth of the power, on average. So a radar |
| Britain (1940). | | | | transmitter can have a much greater range for |
| Airborne Interception (AI) - Developed towards | | | | the same power. This is is especially important in |
| the end of the war, used a Tranceiver | | | | a primary (transmit and receive) radar system, |
| (transmitter/receiver) in a night fighter to find a | | | | where we must detect the reflection of the signal |
| target in the dark, or bad weather, and track it to | | | | we transmit. Likewise a secondary (receive) radar |
| within firing range. | | | | system, for example the navigation system |
| Beacon - A tranceiver was located at the end of | | | | above, will have a bigger range. |
| a runway so that ground staff could guide a | | | | Next we will look at how early computers were |
| returning aircraft to land in bad weather, this | | | | now possible due to these developments. |
| became more and more sophisticated, developing | | | | |