Due to the quantization of electromagnetic fields there is an upper frequency limit in the spectrum of any finite energy transmitted by an electromagnetic system.
由于电磁场的量子化效应，电磁系统发射有限能量的电磁场，其频谱必有一高频率上限。
Thus pulse shaping technique can be used not only shape the spectrum of the transmitted signal to increase the bandwidth efficiency but also to reduce its PAPR.
因此脉冲成形技术不仅能对传输信号进行频谱成形来提高系统的频带利用率，而且还可以减小信号的PAPR值。
The visible spectrum is reflected while the infrared wavelengths are transmitted.
传输红外线波长时会反射出可见光谱。
Normally the spectrum is given as a function of transmittance, the quotient of the intensity of the transmitted radiation and the incident radiation.
在测量范围内可以产生单色辐射光学系统的分光光度计也可以使用。通常光谱是透光度（透射光强度与入射光强度之商）的函数。
This paper proposes a scheme to improve the quality of frequency spectrum of transmitted signals, and also validates the method by the actual test result.
本文就实际工程中遇到的信号频谱恶化问题提出了解决的方案，达到改善发射信号频谱的目的，并用实际的测试结果进行了验证。
The SS communication is a system that the spectrum of signal is spreaded in a wide frequency band when transmitted, and is recovered by the correlation reception when received.
扩频通信是指在发送端将信号的频谱扩展到一个很宽的频带上，在接收端通过相关接收，将信号恢复到信息带宽的一种系统。
The modulation types of data link for UAV are simple, such as BPSK, 2FSK , direct spread spectrum. The transmitted rate and anti-interference performance of them are limited.
目前，无人机数据链系统采用的调制模式都比较简单，如2FSK、BPSK、直接扩频技术等，传输速率与抗干扰能力有限。
The modulation types of data link for UAV are simple, such as BPSK, 2FSK , direct spread spectrum. The transmitted rate and anti-interference performance of them are limited.
目前，无人机数据链系统采用的调制模式都比较简单，如2FSK、BPSK、直接扩频技术等，传输速率与抗干扰能力有限。
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