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发表于 2011-1-11 16:41:41
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回复 9# luckyyu
The length of your time-domain waveform determines the resolution frequency.
For instance, if you want a frequency resolution of 500 KHz, you want your simulation data at least as long as 2.0 us.
If you only need a frequency resolution of 1.0 MHz, you only need 1.0-us simulation data.
Resolution frequency = 1 / (simulation time)
So each data point on the spectrum represents the calculated energy on the specific frequency bin.
If you need N-point FFT result, you will have to set your FFT sampling frequency = resolution frequency * N
N is in power of 2.
Do not confuse this FFT sampling frequency with the clock frequency of the data converter.
You may have a ADC clock (sampling) frequency of 100 MHz, which is much lower a frequency than the FFT sampling frequency. |
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