頻譜分析 取出主頻與雜訊量

請問一下

下圖是頻譜圖, 我想要做SNR分析, 所以需要取出主頻跟雜訊大小, 再透過log去算出值, 請問可以用哪個vi去取值呢?
例如1KHz大約為-5dB, Average Noise:-74dB
![](upload://8hy8308oU70RoZcqzazZkZ0N3wn.jpeg)
garyO40371.7347106481

Extract Single Tone Information.vi

[QUOTE=Glen]Extract Single Tone Information.vi[/QUOTE]

補個圖參考一下
紅色框框處為可取出主頻振幅值 vi ( Extract Single Tone Information.vi >
不過抓取雜訊大小的方式,小弟到是沒有發現此功能vi
是否雜訊量需要用"計算"出來的呢??

![](upload://y2S2Nr0R1KgE2V7w32f0Fs4Nu4G.jpeg)

Signal = ToneSignal + Noise + Distortion

you can extract the tone signal by “Extract Tone.vi”,

Signal - ToneSignal = Noise + Distortion

and this signal is what you want.

try this!