CHEETAH Hardware User’s Manual
Imperx, Inc.
Rev. 6.2
6421 Congress Ave.
7/7/2015
Boca Raton, FL 33487
+1 (561) 989-0006
39 of 152
However, sub-sampling decimation can offer a frame rate improvement by reducing
the number of rows readout from the image sensor.
A/D Bit Depth:
The image sensor has an A/D converter on each column of the
image sensor and reads out two rows simultaneously. There is a finite time required
to reach convergence depending upon the A/D digitization level selected and this can
impact the maximum frame rate.
1)
8-bit digitization: ~9 micro-seconds
2)
10-bit digitization: ~9 micro-seconds
3)
12-bit digitization: ~20 micro-seconds
For example, if 12-bit digitization is selected, then two rows can be digitized in
20 micro-seconds. Since 3136 rows in the C4080 camera must be readout, digitizing
the entire image array consumes 31mS per frame and the frame rate is accordingly
limited.
Output Interface Bandwidth:
The bandwidth of the output interface can also
impact the maximum achievable frame rate. For example, with Camera Link Base (2
taps selected) and with 10-bit digitization and 10-bit output mode selected, the
camera will output 13 full-frames per second limited by the output interface
bandwidth of 2.04 Gbps.
Triggered Dual Video Mode:
The camera
normally overlaps the exposure time
of one frame with the readout of the previous frame. In Triggered Dual Video Mode,
the exposure time and readout time are not overlapped and the total readout time is
the sum of the exposure and readout times.
2.5.3.1 AOI Frame Rate Examples
The Tables below describe resulting frame rate (FR) for various AOIs using Camera
Link Deca output. The frame grabber speed will impact results and values below
assume an x8 speed frame grabber. The camera will calculate and display the actual
frame rate at any horizontal and vertical window selection.
Examples of C4080 Frame Rate performance at full resolution and within selected
AOIs for 10 and 12-bit digitization are described in Table 2.2.
C4080 Frame
Rates (fps)
12-bit
CL 4-taps
10-bit, CL
8-taps
8-bit, CL
10-taps
Full Resolution
27
50
67
3840 x 2160
40
82
90
1920 x 1080
80
172
172
1280 x 720
110
243
243
Table 2.2
C4080 AOI frame rate for various AOIs
