Alpha NIR User’s Guide 412-0007-10 Ver 150
INDIGO OPERATIONS
2 Alpha NIR External Sync Operation
2.1 Procedure for Activating External Sync with IRvista
1) Connect the interface cable between the Alpha NIR and the host computer.
2) Connect the Alpha NIR external sync cable to the back of the Alpha NIR sensor
head.
3) Connect a pulse generator or other trigger source to the external sync cable. The
signal level should be a CMOS level (3.3 volts), with a zero-volt ground level.
4) Power up camera by connecting power supply to it.
5) Open IRvista software.
6) Open the camera control panel.
7) Select external sync mode. The default value is internal sync mode. If the
software is exited, you will have to repeat 6 and 7.
8) Exit from the camera control panel if you are done. The camera should be
triggering off the external sync source. Vary the source frequency to confirm
external sync operation.
Notes:
The EXT_SYNC command is used to put the camera into External Sync Mode. When the
camera is in External Sync Mode, integration and digital data output is initiated by the
ext_sync input pin. A rising edge on the ext_sync pin will cause the camera to begin
integration within a 33.46ms frame, and begin to output the previous frame’s data on the
digital port. Note that there is a one-frame pipeline delay for the output data.
The purpose of External Sync Mode is to control the start of integration for
synchronization to an external event, or to synchronize multiple cameras. The ext_sync
signal must remain high for greater than 100ns to be recognized as a valid rising edge.
The ext_sync signal must be low for a minimum of 100ns before rising.
Integration modes “Normal” and “Special Short” are the
only
supported modes when
using the external sync; “Extended” and “Manual” modes are
not
supported.
The relationship between the ext_sync rising edge and the actual frame integration is
shown in Figure 2. Note that the
end
of integration is fixed; the start of integration varies
based upon the integration time that is defined. The oscillator used in the camera has a
tolerance of 100ppm. At a frame time of 33.46ms, the oscillator tolerance introduces an
uncertainty of 3.346µs in the “end of integration” prediction.
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