对流层散射通信一般采用分集的办法来克服信道的快衰落。所谓显分集是指每个分集信号都有一条物理通道(不同空间或不同频率)与之对应, 相同的信号同时在这几条信道上同时传输。几乎所有关于对流层散射通信参考设计的指导说明都是按显分集的假设制定的。尽管频率选择性衰落可引起码间干扰, 但也可以带来隐分集增益, 我们既可以利用显频率分集也可以利用隐分集方式来改善系统的误码性能, 隐分集是由于信号本身有一定的带宽, 通过散射信道后造成的频率选择性衰落产生的。隐分集的利用有两种情况, 一种是在高速传输时, 信号本身有较宽的带宽; 另一种是低速传输时, 通过扩频方式增大传输带宽使之产生频率选择性衰落。英语翻译

For the troposcatter communication, commonly apply the diversity to control the fast fading of the channel. By “explicit diversity” we mean that each diversity signal has an exclusive physical channel (with diverse spaces or frequencies), while the same signal is transmitted in these channels. Almost all the instructions to the reference design of the troposcatter communication are formulated according to the explicit diversity to be assumed. The frequency selective fading would give rise to intersymbol interference and implicit diversity gain. To improve the BER performance of the system, not only the explicit diversity but also the implicit diversity can be used. The implicit diversity results from the frequency selective fading when the signal inherently having some bandwidth is passing through the troposcatter channel. The adoption of the implicit diversity can be realized either in high-speed transmission, the signal inherently having wider bandwidth; or in low-speed transmission, widening the transmission bandwidth to generate the frequency selective fading with spread spectrum.

对于战术对流层散射传输, 由于对设备体积、复杂度的限制, 显分集技术往往不能采用, 利用扩展频谱的方法, 使得其带宽大于信道相关带宽, 可以有效的克服多径衰落^[1][2]。隐分集的一个明显的优点是设备简单, 而显分集方式设备的复杂度几乎是成倍的增加, 尤其是大于4重的频率分集接收时则更为明显。因此简单利用一个有足够带宽的信号进行消息传输来克服信道衰落就显得非常有吸引力。与显分集中的关键设计参数分集重数相对应, 在隐分集中, 定义传输信号的带宽与衰落相关带宽的比值日语翻译 (简称带宽比)来衡量宽带信号受到频率选择性衰落的程度和有可能获得的分集效果。

The explicit diversity is unavailable for the troposcatter communication in the tactical communication network, due to the volume and complexity of the equipment. Use the spread spectrum to widen the bandwidth more than the related channel bandwidth, which can effectively control multi-path fading^[1][2]. The equipment for the implicit diversity is significantly simple, on the contrary, the equipment for the explicit diversity is manifold complex, especially receiving with four-fold frequency diversity. It goes without saying that the signal with enough bandwidth is very attractive to the information transmission for controlling the channel fading. Corresponding to the diversity multiplicity of the key design parameter in the explicit diversity, the ratio between the bandwidth of the defined transmission signal and the related fading bandwidth (called bandwidth ratio for short) can measure the frequency selective fading and the available diversity effect of the wideband signal.