ECR Title: Add sensor channel from EOM driver to science frames	DCC No: E1500343-v1
Date: 12 August 2015
Requester: Peter Fritschel	Impacted Subsystem(s): LSC, DAQ
Description of Proposed Change(s): Add the channel H1:LSC-MOD_RF45_AM_AC to the science frames (for H1), at 16384 Hz. This is the out-of-loop sensor signal from the recently installed EOM driver for the 45 MHz phase modulation.
Reason for Change(s): The aLIGO EOM driver was recently installed on H1 for the 45 MHz modulation drive, to reduce the noise coming from AM on these sidebands. The EOM driver has an internal amplitude stabilization servo, which significantly suppresses the noise that was coming from the 45 MHz source (harmonic generator). The driver also includes an out-of-loop AM sensor; given the sensitivity of the interferometer (DARM) to this noise, it makes sense to add this sensor channel to the science frames. The coupling of 45 MHz AM to DARM is broadband, so the channel should be stored at the full rate.
Estimated Cost: None (just the time required to modify and reload the model).
Schedule Impact Estimate: Will likely be implemented at LHO on Tuesday, Aug 18, 2015.
Nature of Change (check all that apply): Safety Correct Hardware Correct Documentation	Improve Hardware Improve/Clarify Documentation Change Interface Change Requirement
Importance: Desirable for ease of use, maintenance, safety Desirable for improved performance, reliability Essential for performance, reliability Essential for function Essential for safety	Urgency: No urgency Desirable by date/event: ____________ Essential by date/event: ____________ Immediately (ASAP)
Impacted Hardware (select all that apply): Repair/Modify. List part & SNs: ______________________ Scrap & Replace. List part & SNs:_____________________ Installed units? List IFO, part & SNs: Future units to be built	Impacted Documentation (list all dwgs, design reports, test reports, specifications, etc.): LSC channel list document, T1500014.
Disposition of the proposed change(s): The disposition of this proposed engineering change request is to be completed by Systems Engineering and indicated in the “Notes and Changes” metadata field in the DCC entry for this ECR. The typical dispositions are as follows: Additional Information Required: in which case the additional information requested is defined. The ECR requester then re-submits the ECR with the new information using the same DCC number for the ECR but with the next version number. Rejected: in which case the reason(s) for the rejection are to be given Approved Approved with Caveat(s): in which case the caveat(s) are listed TRB: the ECR is referred to an ad-hoc Technical Review Board for further evaluation and recommendation. It is the System Engineer’s (or designee’s) responsibility to organize the TRB. The System Engineer (or designee) then makes a technical decision based on the TRB’s recommendation. Links to the TRB’s documentation (charge, memos, final report, etc.) are to be added to the “Related Documents” field for this ECR. CCB: a change request for approval of additional funds or schedule impact is to be submitted to the Configuration Control Board. Links to the CCB’s documentation (CR, etc.) are to be added to the “Related Documents” field for this ECR. Concurrence by Project Management: Acknowledgement/acceptance/approval of the disposition is to be indicated by the electronic “signature” feature in the DCC entry for this ECR, by one the following personnel: Systems Scientist Systems Engineer Deputy Systems Engineer