
19
5.6 GAIN AND OFFSET
5.6.1 Standard Configuration:
In the standard configuration, the analog video gain/offset and the digital video gain/offset are
optimized, for good image quality. User access of these adjustments is possible removing the
cover of the camera and adjusting potentiometers on the video board. As a special modification,
access to these potentiometers may be provided through holes in the camera cover; contact
DVC for details.
5.6.2 Manual External Gain Control:
If this option is installed, the internal analog gain control potentiometer is replaced by an external
multi-turn potentiometer that is installed on an external "black box". The potentiometer circuit
connects to the camera through the DB-37 connector (pin 37 is used for the gain control DC
voltage). Since power is derived from the camera AUX. POWER pin (DB-37, pin 36), no external
power supply is needed. A micrometer knob with a locking mechanism allows the user to
accurately calibrate the application and lock-in an optimum gain setting for the application's light
level. The range of operation of the External Gain function is approximately 26 dB, from a
maximum of 43 dB to a minimum of 17 dB. It has a linear response (see curve below).
5.6.2.1 Gain vs. Noise:
The increase of gain increases the noise that is present on the video signal; the signal-to-noise
ratio of the analog video signal is considerably degraded in low-light, high gain situations.
However, some scientific applications benefit greatly from the EGC function. Since DVC
cameras have much higher signal-to-noise ratios than average analog video cameras, they
produce much less noise (even in low-light, high gain situations) than most competing products.
Analog Video Gain (from CCD to Output) vs. Dial Setting
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
Dial Setting
Analog Video Gain (dB)
Figure 5-6: Manual External Gain Control Curve
Содержание DigitEyes Series
Страница 14: ...9 Figure 4 3 TC 245 Gate Level Drawing Texas Instruments 1994 ...
Страница 61: ...56 12 Appendix D Camera Mechanical Drawings Figure 12 1 Camera Mechanical Drawings ...
Страница 63: ...58 Figure 13 2 Camera Noise Spectrum Min Gain Bandwidth 10kHz to 4 2MHz ...
Страница 64: ...59 Figure 13 3 Camera Noise Spectrum Max Gain Bandwidth 100kHz to 4 2Mhz ...
Страница 65: ...60 Figure 13 4 Camera Noise Spectrum Max Gain Bandwidth 10kHz to full ...