Changes between Version 8 and Version 9 of Sensors/Specim

Timestamp:

Nov 30, 2010, 7:08:05 PM (14 years ago)

Author:

mggr

Comment:

--

Sensors/Specim

@@ -25 +25 @@
 Both 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.
 
-The frame grabber lag time is apparently 55ms regardless of frame rate (i.e. a frame is captured 55ms before the nav sync pulse).
+The 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.
 
-Consequently the timing of a start of acquisition is `next_GPS_PPS - navsync_time - 55ms`. [mggr: check this isn't +55ms!]
+Consequently the timing of a start of acquisition is `next_GPS_PPS - navsync_time - <unknown and variable error>ms`.
 
 == Eagle ==