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adc2:simulations:fft_freq_mismatch [2009/11/20 23:11] szymon.kulis |
adc2:simulations:fft_freq_mismatch [2019/03/08 14:08] (current) |
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| -1.22 | -0.10 | -60.0 | -60.0 | 54.8 | -113.2 | 54.8 | 60.0 | | | -1.22 | -0.10 | -60.0 | -60.0 | 54.8 | -113.2 | 54.8 | 60.0 | | ||
| -0.61 | -0.05 | -66.0 | -66.0 | 60.8 | -119.2 | 60.8 | 66.0 | | | -0.61 | -0.05 | -66.0 | -66.0 | 60.8 | -119.2 | 60.8 | 66.0 | | ||
- | | -0.37 | -0.03 | -70.5 | -70.5 | 65.3 | -123.6 | 65.3 | 70.5 | | + | | -0.38 | -0.03 | -70.2 | -70.2 | 65.0 | -123.4 | 65.0 | 70.2 | |
+ | | -0.21 | -0.02 | -75.4 | -75.4 | 70.2 | -128.6 | 70.2 | 75.4 | | ||
+ | | -0.12 | -0.01 | -80.0 | -80.0 | 74.8 | -133.2 | 74.8 | 80.0 | | ||
+ | | -0.06 | -0.01 | -86.0 | -86.0 | 80.8 | -139.2 | 80.8 | 86.0 | | ||
+ | {{:adc2:simulations:fsim_diff_log.png|}} | ||
+ | |||
+ | **remark** : 1%@20Mhz@16kp = 12.7 Hz | ||
+ | |||
+ | **conclusion** : if we want to achive resonable measurement resutls for 10-bit ADC working @ 20 Mhz (and with 16k FFT len) input signal freq should not differ from ideal one more then ~1 Hz. | ||
+ | |||
+ | **conclusion 2 ** : reducing lenght of FFT (fbase is becoming larger) should relax this requirement (but also degrade precision of measurement) |