Modular image acquisition and measurement system with 12-bit pixel-synchronous sampling

This paper describes the requirements, design, and results of a modular data acquisition system with a resolution of 12 bits at up to 20 MHz sampling frequency. The modularity enables the analog-digital conversion to be separated from the digital processing/storage. This allows the latest, best performing ADC (analog-digital converter) to be easily integrated into the system by a re-design of only the AD board with the rest of the system unchanged. The converter employed operates at frequencies up to 20 MHz. The complete system produces measured quantization noise figures of -75 dB and integral non-linearity of -72 dB. The unit can sample video or non-video waveforms. For video applications, an active clamping system is used to ensure that the black level is accurately maintained. The framestore is connected externally using a high-speed digital data bus. This facilitates the inclusion of real-time digital processing units. The framestore used is doubly buffered to permit simultaneous acquisition and readout. The store is 8 Mbytes to accommodate HDTV images and has an input data rate of 40 Mbytes per second.