Imagine if we lost all the satellites that relay cellphone calls, television signals and bank transactions.

想象一下，如果我们失去了移动电话，电视信号和银行传递依赖的卫星。

What's the range of this television signal?

这个电视信号的范围是多少？

Now there is a way of getting television signals without an antenna.

现在有一种不用天线也能接收电视信号的方法。

First, there is broadcast television, which reaches people through television signals.

首先是广播电视，通过电视信号到达人们。

These are companies that broadcast television signals to people who have televisions here in Los Angeles.

这些公司向在洛杉矶这里拥有电视机的人广播电视信号。

We as a species have been sending out radio signals for about 100 years and we have followed that up with television signals.

人类作为一个物种发送无线电信号已经有 100 年的历史了，并且之后我们又发出了电视信号。

In the past, we had no television signal, so the children had to go to the neighbors if they wanted to watch television.

“以前我们家没有电视信号，孩子们想看电视的话就只能去邻居家。

This area contains the International Space Station and over 2,000 government and commercial satellites that provide everything from television signals, GPS, weather forecast, and much more.

这个区域包括国际空间站和超过2000个政府和商业卫星，提供电视信号、全球定位系统、天气预报等等。

For example, run-length encoding, a data compression that was once used for television signals and digital graphics, is based on a similar concept.

例如， 游程编码，一种曾经用于电视信号和数字图形的数据压缩，就是基于类似的概念。

So imagine that same alien civilization looking at the night sky but now there are no radio signals, no television signals, just 300 billion beautiful white lights, quietly shining away.

所以想象一下，同样的外星文明仰望夜空，但现在没有无线电信号，没有电视信号，只有 3000 亿个美丽的白光，静静地闪耀着。

Such a messenger, receiving our radio and television signals, might well re-transmit them back to its home-planet, although what impression any other civilization would thus get from us is best left unsaid.

这种自动化信息装置，在接收到我们的无线电和电视信号后，完全有可能把这些信号发回到原来的行星。至于其他文明行星对我们地球会有什么印象，还是不说为好。

A " satellite" is a piece of equipment that goes around the earth, high up in the space around Earth, that transmits radio signals and television signals from one part of the world to another.

“卫星” 是一种环绕地球运行的设备，位于地球周围空间的高空， 将无线电信号和电视信号从世界的一个地方传输到另一个地方。