Passive localization and tracking system plays an important role in the electronic reconnaissance, because it works silently without electromagnetic radiation and covering larger region.
无源定位与跟踪技术自身不辐射电磁波而且探测距离远，所以它在电子侦察中扮演着越来越重要的角色。
2
Transmitting no electromagnetic wave, passive radar cannot be detected by hostile reconnaissance system.
无源雷达由于不发射电磁波，因而不易被敌方侦察系统探测到。
3
The threaten electromagnetic environment is composed of all kinds of signals, which are emitted by enemy radars, in the fields where the electron reconnaissance equipments exist.