Chapter 3
Hardware Overview
©
National Instruments Corporation
3-3
PCI/PXI-1408 and NI-IMAQ for Win95/NT
8-Bit ADC and LUT
An 8-bit flash ADC digitizes the image, which is passed to a
256-by-8 bit lookup table (LUT) RAM. You can configure the input
LUT to implement simple imaging operations such as contrast
enhancement, data inversion, gamma manipulation, or other nonlinear
transfer functions.
CSYNC Mux
The composite synchronization (CSYNC) multiplexer lets the genlock
and synchronization circuitry select the internally generated composite
synchronization signal or the composite synchronization signal
received from the I/O connector.
Genlock and Synchronization Circuitry
The genlock and synchronization circuitry receives the incoming video
signal and generates a PCLK, HSYNC, and VSYNC signal for use by
the acquisition and control circuitry. The synchronization circuitry
interacts with the voltage-controlled oscillator (VCO) and phase-locked
loop (PLL) circuitry, which generates and controls the PCLK.
VCO and PLL Circuitry
The VCO and PLL circuitry controls the internally generated PCLK
signal frequency. The 1408 device can digitize an incoming video
signal at rates of up to 16.4 MHz.
Pixel Aspect Ratio Circuitry
The pixel aspect ratio circuitry adjusts the ratio between the physical
horizontal size and the vertical size of the region covered by the pixel.
This value is used to figure the picture aspect ratio. For more
information, see the Acquisition Window Control section later in this
chapter.
