Differences

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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)
@@ Line 39: / Line 39: @@
 | -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  |
-| -0.37  |  -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)

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