TI中文支持网Part Number:IWR6843ISKOther Parts Discussed in Thread:IWR6843, , AWR1243
您好！
想咨询的是，IWR6843的信号强度(dbm)是怎么计算的？距离FFT变换后的数值普遍很大，计算出来很大。是10*log10（目标对应数据的abs的平方*1000）？
Chris Meng：
你好,
请参考下面论坛的相关信息：
(+) IWR6843ISK-ODS: How to calcurate "Relative Power"? – Sensors forum – Sensors – TI E2E support forums
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user6408303：
您好！
查了一些资料，介绍RSSI（接收信号强度）Received Signal Strength Indicator一般都是负值，可是参考里面算出来都是正值，比较大的。
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user6408303：
您好！麻烦帮忙回复一下啊，困扰很久了，谢谢！
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Chris Meng：
你好，
在visualizer里计算的是relative power。请问你是否有仔细阅读我上面提到的论坛讨论里的下面的信息？
IWR6843ISK-ODS: How to calcurate "Relative Power"? – Sensors forum – Sensors – TI E2E support forums
Relative power is among the readings themselves i.e relative to each other. It helps in visually noticing targets and in range profile plot (corresponding to 0 doppler) for example we also indicate the targets in the plot that were detected by CFAR. A detection algorithm like CFAR compares cell under test with neighboring cells so it is relative. Visualizer adjustment based on FFT size was to make the display levels not vary based on FFT sizes so one can do a relative comparison among chirp profiles that may have different FFT sizes i.e the display scale does not keep changing among profiles just due to different FFT sizes.
So the relative power was not meant to connect to some dBm level at the input to the SoC, although it can be with two pieces of information 1) What is at https://www.ti2k.com/wp-content/uploads/ti2k/DeyiSupport_传感器_awr1243-how-to-calculate-the-precise-power-on-the-tx-and-rx-pin, which shows the relationship between input power and ADC samples and 2) The scalings etc that happen from ADC to the power calculation which information is in the spread-sheet that was pointed out earlier. However, this is unnecessarily complicated compared to just doing 1) by estimating the average power of the ADC samples [1/N sum(|.|^2)], which for example you can do by streaming out the ADC samples using mmwave studio (or also in demos that have LVDS streaming feature implemented) and doing an off-line computation.
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user6408303：
您好！
里面有具体的计算方法：Below is an example calculation to get the amplitude level at the LNA input ->If you are using 12bit ADC mode , a value of 0x7FF corresponds to positive peak value at the ADC input, which corresponds to 1V peak voltage at the ADC input. 1V peak corresponds to 10dBm power (50 ohms system , assuming sinusoidal signal). Now if the RX gain setting is 30dB , this means at the LNA input the power level is (10dbm -30dbm ) = -20dBm.
想确认的是1243芯片10dBm是不是10*log10(1V*1V/2/50ohm) =10dbm这样计算出来的？如果是IWR6843ISK,16bit ADC mode ,也是1V peak voltage吗？
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Chris Meng：
你好，
你上面引用的是根据ADC数据的值，反推LNA输入时候信号幅度。在visulizer里显示的都是检测到的目标的相对能量，是两个概念。
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user6408303：
你好！知道是两个概念，现在想确认的是计算公式中的10dbm是不是根据10*log10(1V*1V/2/50ohm)计算出来的，还有这个是针对1243芯片，如果是6843芯片，也是使用10dbm-(RX gain) ?
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user6408303：
你好！
知道是两个概念，现在想确认的是计算公式中的10dbm是不是根据10*log10(1V*1V/2/50ohm)计算出来的，还有这个是针对1243芯片，如果是6843芯片，也是使用10dbm-(RX gain) ?
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Chris Meng：
你好，
AWR1243射频部分和IWR6843是类似的（除了倍频）。
user6408303 说：现在想确认的是计算公式中的10dbm是不是根据10*log10(1V*1V/2/50ohm)计算出来的
建议你到英文论坛e2e.ti.com上确认。
