求英译汉，机器翻译不要
Amplitude Modulation
Modulating a carrier wave by adding another, lower frequency signal results in a signal that has most of its power concentrated in the carrier, with the rest shared between two sidebands, one above the carrier in frequency and one below it. The highest frequency in the modulating signal is typically less than ten percent of that of the carrier. The process of creating these sideband frequencies by adding another signal to the carrier is known as heterodyning. In the simplest case, the carrier can be modulated by adding another single-frequency sine wave signal to it, changing the carrier's shape (or envelope) as illustrated above. The sideband frequencies account for approximately 33% of the transmitted power. If a more complex modulating signal (such as an audio signal) is used to modulate the carrier, the sidebands account for only about 20-25% of the total transmitted power.
Consider, for example, a 100 kHz carrier that is modulated by a steady audio signal (or tone) of 5 kHz. When these signals are added, two sidebands are produced. One sideband has a frequency equal to the sum of the carrier and the modulating signal (100 kHz + 5 kHz = 105 kHz), while the other sideband has a frequency equal to the difference between the carrier and the modulating signal (100 kHz - 5 kHz = 95 kHz). The two sidebands are 5 kHz equidistant from the carrier (one above it and one below it), giving a total bandwidth for the modulated signal of 10 kHz (105 kHz - 95 kHz). The resulting frequency spectrum is illustrated below
Of course, most audio signals (speech and music, for example) are far more complex than a single-frequency audio tone, and are composed of many different frequencies. When a carrier is modulated with a more complex audio signal, therefore, all of the frequencies present in the audio signal are represented in the resulting output signal. In this case, the total bandwidth is the difference between the sum and the difference values of the carrier and the highest frequency component of the modulating signal. To simplify things, the modulated signal bandwidth will be twice that of the modulating signal. For a modulating audio signal with frequency components ranging from 0 - 6 kHz, therefore, the bandwidth of the modulated signal for a 100 kHz carrier will be 106 kHz - 94 kHz = 12 kHz. This produces a more complex frequency spectrum, which might look something like that shown below.
调整载波通过增加别的更低的频率信号导致有被集中的大多数它的力量在载体，当休息分享在二边带，一在频率的载体之上和一之间在它之下的信号。 在调整的信号的最高的频率少于那的百分之十典型地是载体。 创造这些边带频率的过程通过增加另一个信号到载体叫作外差。 最简单的情况，载体可以通过增加另一个单频正弦波信号调整到它，改变carrier' s形状(或信封)如上所示。 边带频率占大约33%被传送的力量。 如果一个更加复杂的调整的信号(例如一个可听声信号)使用调整载体，边带只占大约20-25%总被传送的力量。
考虑，例如由一个平稳的可听声信号的一个100 kHz载体(或口气) 5 kHz调整。 当这些信号增加时，二边带被生产。 一边带有一个频率相等与载体和调整的信号(100的总和kHz + 5 kHz = 105 kHz)，而另一边带有一个频率相等与在载体和调整的信号(100 kHz - 5之间的区别kHz = 95 kHz)。 二边带是5 kHz等距离从载体(一在它之上和一在它之下)，给被调整的信号的总带宽10 kHz (105 kHz - 95 kHz)。 发生的频率光谱如下被说明。
当然，多数音频信号(例如讲话和音乐)比单频音频口气复杂和由许多不同的频率组成。 因此时，当载体调整与一个更加复杂的可听声信号所有频率当前在可听声信号在结果输出信号代表。 在这种情况下，总带宽是在总和和载体的区别价值和调整的信号的最高的频率组分的之间区别。为了简化该问题，被调整的信号带宽两次将是那调整的信号。 为与范围从0 - 6 kHz，因此，被调整的信号的带宽一个100 kHz载体的将是106 kHz - 94的频率组分的一个调整的可听声信号kHz = 12 kHz。 这导致一个更加复杂的频率光谱，也许看起来就好像我现在所看到的东西。
加入一个信号，表明其权力集中在承运人之间的两个边带之一以上的高频载波和它下面的一个共享的休息，低频率信号的结果，载波调制。调制信号的最高频率一般低于10％的载体。加入另一个信号向承运人创建这些边带频率的过程被称为外差。在最简单的情况下，承运人可调制加入另一个单频正弦波信号，改变承运人的形状（或信封），如上图所示。边带频率占约33％的发射功率。如果一个更复杂的调制信号（如音频信号）是用于调制载波，边带只有约20-25％的总发射功率。
考虑，例如，一个100 kHz的载体，是一个稳定的音频信号（音）的5千赫调制。当这些信号，两个边带的产生。一个边带的频率等于载波和调制信号（100千赫+ 5千赫= 105千赫）的总和，而其他单边带频率等于载波和调制信号（100千赫之间的差异 - 5千赫= 95千赫）。两个边带是5 kHz的载波（上面和下面一行）等距，给人一种总带宽为10 kHz（105千赫 - 95千赫）的调制信号。由此产生的频谱如下图所示
当然，大多数的音频信号（语音和音乐，例如），远远超过了单频音频音调复杂，是由许多不同频率组成。当一个载体，是一个更复杂的音频信号进行调制，因此，所有目前在音频信号的频率代表产生的输出信号。在这种情况下，总带宽的总和与差值的载体和调制信号的最高频率分量之间的差异。为了简化问题，调制信号带宽将调制信号的两倍。因此，带宽为100 kHz载波调制信号调制的音频信号频率范围从0组件 - 6千赫，106千赫 - 94千赫= 12千赫。这将产生一个更复杂的频谱，这可能看起来如下所示的东西。
