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MROI.Tip-tiltSystems History

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March 16, 2007, at 05:00 PM by John Young -
Changed lines 10-26 from:
* Detector choice: EMCCD or conventional CCD
* If EMCCD, do we ever need to use photon-counting mode?
* How to handle dispersion offset between TT band and science/FT bands, e.g.
* Does subframe need to move on TT detector during an observation?
* How do we determine the colour of the target?
* Is dispersion significant when determining a pointing model?
* What ratio sample rate/bandwidth is needed?
* How do we measure the temporal seeing with the TT system?
* How do we choose the bandwidth for a particular observation?
* How to manage range of target magnitudes 0-16, e.g.
* Do we need ND filters?
* What detector parameters need to be varied
* Do we always use the full aperture?
* Centroiding algorithm
* Can we achieve the required stability of reference direction?

Deleted lines 27-28:
* Stability of reference direction
* Sample rate/bandwidth
Added line 29:
* At what level is the interface to RTC?
March 16, 2007, at 03:44 PM by John Young -
Changed lines 4-6 from:
* Answer questions in requirements doc.
* Insert values from new system error budget.
Added line 14:
* Critical software issues
March 16, 2007, at 03:38 PM by John Young -
Changed lines 1-16 from:
Original tip-tilt memo: [[Attach: INT-402-MIS-0034.pdf]]
Original tip-tilt memo: [[Attach: INT-402-MIS-0034.pdf]]

Requirements document: [[Attach: INT-403-ENG-0003.pdf]]

Specifications of tip-tilt secondary mirror: XXX

Open questions:

* Derived requirements
* Stability of reference direction
* Sample rate/bandwidth
* ROM cost

The expression for the control system error factor from the tip-tilt memo is
{$$ \gamma = \left[ \frac{2}{\Omega} \tan^{-1} \left(\frac{\Omega}{2}\right) \right]^{1/2} , $$}
where {$ \Omega $} is the ratio of sampling frequency to 3dB bandwidth.
March 16, 2007, at 03:00 PM by John Young -
Added line 1:
Original tip-tilt memo: [[Attach: INT-402-MIS-0034.pdf]]
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