求翻译：4. 错频技术：同类检测系统中的两套检测天线直线距离≥15米的情况下不需要同步，减少了同步线的费用，为工程实施和安装使用带来方便。是什么意思？

4. the wrong frequency: two sets of similar detection system detection of linear antenna distances ≥ 15 m cases do not need to be synchronized, reduce the cost of the synchronous lines, used for project implementation and installation convenience.