LIGO Document E1500371-v1

ECR: Add a 45.5MHz phase-locked OCXO

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E - Engineering documents
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Compared to the original design we are using very large modulation indices. This makes us more sensitive to RF AM. Furthermore, the 45.5MHz is generated as the 5th harmonics of the 9.1MHz which results in poor amplitude and phase noise. We propose to add a 45.5MHz phase-locked OCXO to clean up both amplitude and phase noise.
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Notes and Changes:
Systems endorses the purchase of a single, custom, 45.5 MHz phase-locked, OCXO source (and associated electronics) for diagnostic purposes. Until, and unless, diagnostic testing indicates that amplitude and phase noise on this modulation source is a limitation, there is no approved change to the baseline design (no approved ECR).
The electronic approval request is removed. The ECR is not rejected, just dormant, pending the results of diagnostic testing.

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