Changes between Version 8 and Version 9 of Sensors/Specim


Ignore:
Timestamp:
Nov 30, 2010 7:08:05 PM (9 years ago)
Author:
mggr
Comment:

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  • Sensors/Specim

    v8 v9  
    2525Both Specim instruments are connected to a nav-sync box that timestamps the start of acquisition against GPS time.  This measures the time to the next GPS pulse-per-second, from the first start of integration pulse from the camera that occurs after the start of acquisition pulse from the recording system.
    2626
    27 The frame grabber lag time is apparently 55ms regardless of frame rate (i.e. a frame is captured 55ms before the nav sync pulse).
     27The frame grabber lag time is unknown.  Previously it was thought to be 55ms regardless of frame rate (i.e. a frame is captured 55ms before the nav sync pulse), but this was actually a once-off correction applied by Specim for a single dataset.  What was called the frame grabber lag time is actually an unknown timing error in the system.  Further work is underway to isolate this.
    2828
    29 Consequently the timing of a start of acquisition is `next_GPS_PPS - navsync_time - 55ms`. [mggr: check this isn't +55ms!]
     29Consequently the timing of a start of acquisition is `next_GPS_PPS - navsync_time - <unknown and variable error>ms`.
    3030
    3131== Eagle ==