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发表于 2008-1-2 13:58:23
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<DIV class=quote><B>以下是引用<I>rousong</I>在2008-1-2 12:42:03的发言:</B>
我测的是24dbm左右,应该是发射功率什么的吧</DIV>
<P>
测量条件不一样,具体参照34.121
When the RRC Filter for the channel power measurement is turned on, the results are typically about 0.25 dB lower than the thermal power measurement results.
Thermal power performance is only specified for signals down to -10 dBm, while the channel power measurement is able to accurately measure signals down to -61 dBm
RRC FILTER
The signal can be filtered in the DSP with a root-raised cosine (RRC) filter with a rolloff of 0.22 and a bandwidth equal to the chip rate (3.84 MHz) to comply with 3GPP 34.121 conformance specifications that require RRC filtered power. The filter can also be turned off for conformance specifications requiring a mean power measurement. When the RRC filter is Off , the bandwidth of the channel power measurement is greater than (1+alpha) times the chiprate, where alpha=0.22.</P>
<P>照字面的理解应该是Thermal power 测量的信号贷款大于channel power ,因为没有大家RRC FILTER ,所以测量的功率比channel power 大0.25DB左右,多余的部分应该是噪声功率。channel power 的测量则打开了RRC FILTER,进行了必要的滤波,所以功率稍小。</P> |
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