NAC Image Technology MC-529, User Manual

Page: 169 / 180

(00235) 7-29
APPENDIX E IRIG-B
E1. Standard:IRIG Standard 200-98, IEEE1344
Compatible with 1kHz carrier modulation IRIG-B (B120, B122, B123 format).
Not compatible with unmodulated IRIG-B (B000, B003 format).
E2. Modulated IRIG-B Waveform and Exposure Time
Modulation in the following diagram is for P bit , 0 bit and 1 bit. The standard time is the top portion.
There are 100 bits per second and 10 carriers per 1 bit. There are P bits for each 0.1 sec.1carrier is
1msec.
P (reference ) bit 0 bit 1 bit
The example in the figure below shows the IRIG-B and the exposure time for 100 pps.
The figure below shows “x” as 1 or 0 bit.
P P x x x x 0 x x x P x x x x 0 ・・・ P P
0.1sec
1sec
IRIG-B
Exposure timing
100pps
・・・
Standard timing
At any photographic speed, the IRIG-B and exposure start must have the same standard time (with
an exposure phase shift setting of 0°).
E3. Exposure Phase Shift Function
Uses as a method to implement higher resolution and high speed recording when using multiple
cameras. Depending on the camera placement, it may be possible to ignore the parallax during
infinite telescopic photography. The settings are in phase angle degrees (units 0~359).
Exposure phase shift settings can only be set with the camera control software.
Example)
At 1024 x 1024 pixels, each camera is set to 2,000 frames/sec, and four cameras are subject to IRIG
synchronization. With the respective phase shift for each camera set to 0°, 90°, 180°, and 270°,
photography can be conducted at 2,000 x 4=6,000 pps.
2,000 frames/sec involves a frame interval of 500
μ sec so each camera shifts only 0 μ sec, 125 μ sec,
250 μ sec, and 375 μ sec from the IRIG-B standard time.
Note ) With standard multiple synchronized camera systems (such as GX-HUB system), the
exposure time for all of the cameras is synchronized so the phase shift should be set to 0°.