xiaotian28

请教－为什么在FCC part15B中 1GHz以上 测试data的peak limit值会比法规规定的要高出20dB？法规规定960MHz以上limit值为54dBuV ,而 测试data中limit值为74dBuV 为啥会多出20dB呢，请参考附件中红色mark 部分，不解，请老兄们帮小弟解惑一下哦

cloudfgl

仔细看看part 15

15.35 （b）

(b) Unless otherwise specified, on any frequency or frequencies above 1000 MHz, the radiated
emission limits are based on the use of measurement instrumentation employing an average detector function. Unless otherwise specified, measurements above 1000 MHz shall be formed using a minimum resolution bandwidth of 1 MHz. When average radiated emission surements are specified in this part, including average emission measurements below 1000 MHz, there also is a limit on the peak level of the radio frequency emissions. Unless otherwise specified, e.g., see §§ 15.250, 15.252, 15.255, and 15.509-15.519 of this part, the limit on peak radio frequency emissions is 20 dB above the maximum permitted average emission limit applicable to the equipment under test. This peak limit applies to the 24 total peak emission level diated by the device, e.g., the total peak power level. Note that the use of a pulse desensitization correction factor may be needed to determine the total peak emission level. The instruction manual or application note for the measurement instrument should be consulted for termining pulse desensitization factors, as necessary.

xiaotian28

我知道按FCC part15 B 规定PK比AV值高20dB，可谁知道为什么他们会这样规定？依据评判的标准是啥啊？

hedeye

标准上就是起个定义而已,应该无太大的依据.

forestxsl

点电话去FCC问问

peterliao

一般来说，测试场强时，PK值比AV值要高，但具体为什么1G以上的PK值要定高20dB，我想可能是根据统计的结果得到的,毕竟在电磁兼容测试工程实践中，时变的的信号目前是没有公式去算的. 这里可能还要涉及一个PK,QP,AV值之间关系的问题,向大家推荐一个我搜索到的blog,与大家分享:
http://blog.ednchina.com/sichupiaobo/6182/message.aspx

nicholas_t

首先这个是法规规定的，但是根据点我觉得是在 Peak和Avg的 RBW VBW不一样所导致的。需要强调的一点就是：1G以上是 Peak 74 Avg 54是都需要符合要求的。并非是只看Avg的。

happydu

To:nicholas_t

"需要强调的一点就是：1G以上是 Peak 74 Avg 54是都需要符合要求的。并非是只看Avg的。" 这在法规中有依据么？

libochen1982

记得和duty cycle有关 Peak 是100% duty cycle, average是0%duty cycle 印象中记得是20dB 应该是这样 我忘记得差不多了

weilly2001

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