The evolution of video and sound devices.
电视和音频装置的发展
Early history of TV
电视的早期历史
The first public TV broadcasts were made in the USA in 1925.
第一台公共电视放映是在1925年的美国。
Later, in 1928, the first long-distance TV broadcast was made between the UK and the USA.
之后，1928年，英国与美国之间的长途电视播送成功。
Regular public broadcasting followed shortly afterwards, first beginning on 11 May 1928 in New York and on 20 August 1929 in London.
正规的公营广播不久后也出现了，最初开始于1928年5月11日，在纽约，以及1929年8月20日，在伦敦。
Many different people contributed to the development of TV.
许多人为电视的发展付出了贡献。
Most early TV broadcasts were made using a system developed by John Logie Baird in the UK.
大多数的早期电视广播应用的是由英国John Logie Baird发明的系统。
However, his system was very primitive and had many drawbacks.
但是，他的系统很初级并且有很多弊端。
An American, Philo Farnsworth, made important breakthroughs in the development of TV in the late 1920s and early 1930s. Modern TVs use many of the principles first discovered by Farnsworth.
一个美国人，Philo Farnsworth，在20年代末，30年代初对电视的发展做了重要的突破。现代电视使用了很多Farnsworth发现的原理。
John Logie Baird constructed the first colour TV in 1928, but it was not until 1938 that the first colour TV programme was broadcast.
John Logie Baird于1928年制造出第一台彩色电视机，但直到1938年第一个彩色电视节目才播出。
It took more than two decades, though, until 1951, for regular colour TV broadcasts to begin in the USA.
这花费了二十年，可是，直到1951年，普通彩色电视广播才开始于美国。
Regular colour TV broadcasts were delayed in the UK until 1967.
普通彩色电视广播推迟到1967年才在英国出现。
However, within a short time nearly all TV broadcasts were made in colour, and within five years more colour TVs than black-and-white TVs were being used.
但是，在很短的时间内，所有的电视广播都成为了彩色，五年内，彩色电视的使用超过了黑白电视。
The modern age: satellite TV
现代：卫星电视
Satellites TV used to broadcast TV beginning in 1962. Satellites allow TV to be broadcast live over vast distances, with everyone recieving the same broadcast at the same time.
用人造卫星进行电视播放开始于1962年。卫星使得很远地区能同时接收到相同的广播。
They also make TV accessible to people who live far away from cities, and satellite dishes can often be seen distributed throughout the countryside and remote areas.
它们也使远离城市的人们可以收看电视，在农村和边远地区可以看到卫星电视。
Of course, only a small percentage of people own satellite dishes.
当然，只有少部分人拥有卫星天线。
However, most people still benefit from satellite TV, as local TV companies broadcast the signals they get from satellite receivers to the population living nearby.
然而，大多数人仍然受益于卫星电视，因为当地的电视公司把从卫星接收器收到的信号播送给附近的居民。