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precision_timing:thunderbolt_damping [2013/01/08 19:00] (current) |
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+ | ====== Trimble Thunderbolt Damping ====== | ||
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+ | Tbolt users, | ||
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+ | One of the questions I often hear is what should the Tbolt's Damping be set to? | ||
+ | Assuming the Dac_Gain and TC_Sec are correctly set, then Damping is the easy one; | ||
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+ | 1) If your concerns are freq accuracy and you don't care about Phase accuracy, Set the damping from 1 to 1.5 with the Factory default of 1.2 being a good Nominal Value. | ||
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+ | 2) If your concerns are Phase accuracy and are willing to accept some increase in freq noise, Set the damping from 0.5 to 0.7 with 0.6 a good nominal value. | ||
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+ | 3) And for a compromise between both Phase and Freq Set the Damping from 0.7 to 1.0, with 0.85 a good nominal value. | ||
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+ | Lower damping settings < 1.0 are best used only with longer TC settings > 100 | ||
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+ | The non technical description of what damping does (in the Tbolt) is: | ||
+ | The TC setting is the Tbolt's Freq correction Time Constant (short term Osc error) and the Damping setting effects the Tbolt's Phase correction time. ( Long term Phase error) The way that Damping controls Phase is by causing the Freq error correction to Overshoot. | ||
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+ | As to how much difference changing the damping makes. | ||
+ | The difference in phase error between slow and fast damping setting can be 10 to 1 when the TC is set to the high value needed to get best freq noise. | ||
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+ | Hope this clears up some of the Damping setting questions. | ||
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+ | Here is the response with various TC and Damping settings | ||
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+ | {{:precision_timing:tbolt_damping.gif|}} | ||
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+ | Warren | ||