... | ... | @@ -21,7 +21,8 @@ If we now equate $`IF_A=IF_B`$ and insert the DDS frequencies $`f_{DDS1}(FTW_1)` |
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{f_{OCXO}\over{f_R}} - 1 = { {2^{48} \cdot 2^2}\over{ 10 (FTW_1 + { {FTW_2}\over{ 2^{10}}}) }}-1
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```
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DDS1 can be used for coarse frequency adjustments. Around a fractional frequency of zero, changing FTW1 by 2 steps (AD9912 is a 47-bit DDS!) changes the output frequency by 1.8e-14 as follows:
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DDS1 can be used for coarse frequency adjustments. Around a fractional frequency of zero, changing FTW1 by 2 steps (AD9912 is a 47-bit DDS!) changes the output frequency by 1.8e-14 as follows.
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This is output from the **scripts/ustep_calc.py** script. Note that a library like [bigfloat](https://pypi.org/project/bigfloat/) is (probably) needed for accurate computation at 18+ digits of precision.
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```
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uStep output fractional frequency y
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