Hawk Instruction Manual
Document number
Revision
File name
Date
Page
2015-07-22-05
V1.1
HK82x_IM_v1_1
30
th
Jul 2015
9 of 14
Images are read from the Charge Coupled Device (CCD) sensor in progressive format, i.e. a complete is read
every 50/60Hz. Progressive to interlace conversion occurs within the camera firmware. The order of the odd/even
line combination is reversed for odd/even fields to preserve vertical resolution.
3.1.5
Iris Control
The camera Iris control circuit can be used with either a Video or DC lens. Further details of iris functionality are
provided in section 3.2.1.
3.2
Functionality
3.2.1
Automatic Light Control (ALC)
The ALC is enabled by default.
The ALC level is determined by an average across the whole image within a field.
Three modes of automatic light control exist:
1. Digital Gain: To achieve the set video level digital gain automatically adjusts the scaling on the internal
video signal. The set video level is compared with the average video in each video field to determine the
required digital gain to reach equilibrium. If ALC is disabled, digital gain remains fixed at the last level.
2. Auto EXP: Auto EXP will automatically adjust the internal Electronic Shutter to vary the effective
exposure of the CCD. The set video level is compared with the average video in each video field to
determine the required level of exposure to reach equilibrium. Note: Auto EXP only functions if ALC is
enabled. If ALC is disabled, exposure is fixed at the field period.
3. Auto Iris (Video and DC Iris lens modes): the camera has the capability to drive both Video Iris and DC
Iris lenses and can automatically detect which lens type is connected at power-up.
o
Video lens mode: the camera produces a separate iris video signal that is representative of the
image acquired by the CCD.
o
DC lens mode: the camera produces a DC drive signal that is them inverse of the light level
acquired by the CCD, i.e. if the CCD light level is low the DC iris signal will be high to open the
iris.
Notes:
o
If ALC is disabled the exposure is fixed at 1 field period i.e. 20msecs and digital gain = 1.
