The operating range for extended target is calculated by considering of the target finding ability of eyes, contrast of target luminance, discrimination level and detection probability.
并综合考虑人眼的目标发现能力、目标的亮度对比度、观察等级和探测概率的要求，计算出面源目标的作用距离。
When we use it to test the underwater target strength, one problem is how to discriminate the direct sound of the source with the echo reflected from the target, finding the target character quickly.
当利用它进行水下目标强度测试时，一个很实际的问题就是怎样区分声源直达声和目标反射回声，快速找出目标特性。
When we use it to test the underwater target strength, one problem is how to discriminate the direct sound of the source with the echo reflected from the target, finding the target character quickly.
当利用它进行水下目标强度测试时，一个很实际的问题就是怎样区分声源直达声和目标反射回声，快速找出目标特性。
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