发射器和接收器工作区域是怎么样的

当然，自然界中的所有事物都是非线性的，它只是程度的关系。
对于发射机，它通常在高功率，强非线性状态下使用，以获得更好的功率效率（强烈如同超过1％的失真，可能是-40 dBc左右的双音水平），因此非
线性行为强烈影响信号的质量。
为了补偿非线性效应并且允许发射机以非线性模式操作但仍然产生高质量信号，在预失真信号方面需要付出很多努力。
对于接收器，它通常在低功率下以弱非线性状态使用（弱到低于0.01％的失真，可能是-80 dBc左右的双音水平），因此非线性行为具有
与噪声和接收器平坦度等其他缺陷相比，对信号质量几乎没有影响。
甚至无线电中的滤波器虽然是无源的，但却是非线性的。
Google Passive Intermodulation（PIM）就是一个例子。



     以下为原文

  Of course, all things in nature are Non-Linear, it it just a matter of degree about how much.

For transmitter, it is commonly used at high power, in a strongly non-linear state for better power efficiency (strongly as in more than 1% distortion, maybe a two-tone level of -40 dBc or so) and so the non-linear behavior strongly affects the quality of the signal.  There is a lot of effort in pre-distorting the signal such to compensate for the non-linear effect and allow a transmitter to operate in a non-linear mode but still produce a high quality signal.

For a receiver, it is commonly used at low power in a weakly non-linear state (weakly as in less than 0.01% distortion, maybe a two-tone level of -80 dBc or so), and so the non-linear behavior has almost no effect on the quality of the signal, relative to other defects such as noise and receiver flatness.

Even the filter in a radio, although passive, is non-linear.  Google Passive Intermodulation (PIM) for an example.

主要原因可能是系统的效率（如果大型发射机的运行成本）。
从发射器方面：假设您在纽约市拥有可提供200KW功率的FM发射器。
如果使用A类（线性）功率放大器，效率只有50％。
这意味着你需要400KW / h的功率。
如果您使用非线性的不同功率放大器，但效率为90％，则需要大约220KW。
现在，如果每千瓦的总成本是0.3美元，那么第一箱的变速器的能源成本将是400 * 0.3 =每小时120美元，或每天2880美元或每年1,051,200美元。
在220KW的情况下，每小时220 * 0.3 = 66美元或每天1,584美元，或每年578160美元。
对于接收器而言，您获得的功率非常低，并且效率可能不那么重要，因为总运营成本非常低（看看您的手机能耗，大部分功率是驱动CPU而不显示接收器）。
如果信号在线性模式下工作，则除非DSP后处理能够做到这一点，否则额外的硬件需要过滤掉一些失真。
我确信芯片上的电话系统供应商可能已经或去过那里，以节省每一点电力。



     以下为原文

  The main reason is probably efficiency of the system (and if that big transmitters cost of operation). 
From transmitter side: Let say you have FM transmitter in New York City that deliver 200KW of power. If you use A class (linear) power amp you only have 50% efficiency. That mean the you need 400KW/h of power. If you use different class of power amp  that is non linear however deliver 90% efficiency you will need around 220KW.  Now if the total cost per KW is $0.3,  then cost of energy for the transmission for the first case will be 400*0.3=  $120 per hour, or  $2880 per day or $1,051,200 per year.
In case of 220KW you get 220*0.3= $66 per hour or $1,584 per day, or $578160 per year.  

For receiver the power that you receive is very low, and the efficiency might be less important as total operational cost is vey low (look on your cell phone energy consumption, were most of the power is to drive CPU and display not the receiver). If the signal operate in linear mode less additional hardware need to filter some of the distortion unless the DSP post processing can do that. I am sure that vendors of phone system on chip probably when already or going there, to save every bit of power.