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5.10 ACCESS PORTS :
Upto five access ports are provided on the top surface of the camera cover, as shown in the
figure below:
Figure 5-13
: Access Ports (Top view)
5.10.1 Access port for analog gain control :
Access to the internal analog gain control potentiometer is provided via a 1/8” hole in the camera
cover. The range of operation is approximately 30dB; It has a linear response.
Note (1): 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 External Gain Control
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.
Note (2): The analog gain potentiometer is factory set via a special calibration procedure to get
the maximum sensitivity without violating the SNR specification of the camera. This
potentiometer should only be adjusted in special situations by qualified operators.
5.10.2 Access port for analog offset control:
Access to the internal analog offset control potentiometer is provided via a 1/8” hole in the
camera cover. The range of operation is approximately 0-15 IRE; It has a linear response.
Note (1): The RS-170 standard specifies a "setup" or "pedestal" of 7.5 IRE units. This is obtained
approximately half-way through the adjustment range - actual settings will vary slightly from unit
to unit. The analog offset potentiometer is factory set via a special calibration procedure for 7.5
IRE. This potentiometer should only be adjusted in special situations by qualified operators.
5.10.3 Access port for digital gain control:
Access to the internal digital gain control potentiometer is provided via a 1/8” hole in the camera
cover. The range of operation is approximately 10dB; It has a non-linear response.
Note (1): The increase of gain increases the noise that is present on the video signal; the signal-
to-noise ratio of the analog video signal (prior to digitization) is considerably degraded in low-
light, high gain situations. This can degrade the Effective Number of Bits (ENOBs) of the digital
video signal. However, some scientific applications benefit greatly from the External Gain
Control function. Since DVC cameras have much higher signal-to-noise ratios than average
Camera Cover (top surface)
Lens
Connectors
Analog Analog Gamma Digital
Offset Gain adjust Gain Offset
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