你需要知道的调制器和解调器

未知 2017-06-23 09:37:06 0评

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  你需要知道的调制器和解调器

  调制,在RF应用程序的上下文中,指两个正弦信号的混合。射频调制器是一种接收输入信号并输出调制信号的装置。调制器基本上有两个输入和一个输出。一个输入通常称为“信息”输入。另一个输入是rf载波输入。

  输出信号是两个输入信号的复合。例如,在DVD播放器中,调制器将信号转换为可用于电视接收机的格式。

  解调器,另一方面,以调制信号和输出的信息信号和载波信号。载波信号没有得到进一步的使用。在系统中,调制器放在发射机之前,解调器在接收机之后。

  无论信号是话音还是数据,各种调制技术都可用,如模拟调制(调幅、调频)和数字调制(频移键控或FSK、幅移键控或询问、移相键控或PSK)。

 你需要知道的调制器和解调器

  In amplitude modulation (AM or ASK), the amplitude of the carrier varies in accordance to the information signal. In frequency modulation (FM or FSK), the frequency of the carrier varies in accordance to the information signal. In phase modulation (PM), the phase of the carrier varies in accordance to the information signal.

  ASK can also be combined with PSK to create hybrid systems, such as quadrature amplitude modulation (QAM), where both amplitude and phase are changed at the same time.

  All have their pros and cons. ASK, for example, is simple to employ, but can be susceptible to noise. FSK is less susceptible to noise, but (in theory at least) requires a larger bandwidth/bitrate than ASK.

  Similarly, PSK is less susceptible to noise and is bandwidth efficient, but requires synchronization in frequency and phase and therefore complicates receivers and transmitter design.

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