36
Theory of Operation
X64-AN Quad User's Manual
Internal Sync
In Internal Sync mode, a clock generator is programmed to generate the desired pixel clock and time
base signals. The clock generator produces separate horizontal and vertical sync signals that match the
desired video format. These signals, called horizontal drive (HD) and vertical drive (VD), are then
output to the camera. The frequency synthesizer can be programmed to generate any clock frequency
up to 50MHz with less than 1ns jitter. Internal Sync mode easily supports both standard and non-
standard camera timing.
The horizontal and vertical timing created by the clock generator is output to the camera as HD/VD
signals: called Master Mode. It is also possible to deactivate the VD output for use with cameras that
have such a requirement.
Note that the X64-AN Quad in Master Mode is independent from the selected source of
synchronization. It is therefore possible for X64-AN Quad to send VD/HD to the camera, but still
synchronize to the VS/HS present in the composite video signal.
X64-AN Quad allows the same VD/HD to be sent to all four cameras simultaneously. This is useful to
genlock cameras together. X64-AN Quad has two master mode controllers allowing control of up to
two independent sets of cameras.
Analog Composite
Video
Valid Pixels
A/D
LUT
Cropper
Clock
Generator
PLL
VS
HS
Pixel Clock
HD
VD
Cam
Pixels
Figure 18: Internal Sync in Master Mode Block Diagram
When using Internal Sync, the horizontal reference for acquisition is HD. This is equivalent to a
horizontal front porch of 0 pixels. The horizontal signal is used as a time reference to configure the
clamping pulse delay and duration parameters.
