Back End Overview - FujiFilm SonoSite sII Service Manual

Back End Overview

The Back End subsystem is responsible for the conversion of raw acquisition data into a raster image ready
for display. The Back End subsystem also contains the video data path that supports generation of video
comprising of the ultrasound image as well as graphics annotation. Video generation of both standard
composite interlaced video and progressive scan video is supported. Most functionality is within the ASIC
but the memory resources for acquisition memory, and display memory are found in external memory
components. The conversion from PC type video to TV type video is also performed externally.
Control is received initially from the CPU to setup each functional block and afterward the hardware is
completely data driven. This control takes the form of programming setup registers inside the blocks and
setting up scan conversion tables. Each block provides temporary storage as required to buffer data and
keep their respective processing pipeline full and operating. Also note that the block diagrams show only
the data path, but each block is responsible for generating any necessary memory addresses for their
respective input data stream.
The SonoSite SII Back End subsystem is shown in the figure below.
Figure 4.3 Back End Subsystem Block Diagram
The Back End Subsystem performs processing encompassing three main data domains, acquisition data,
raster data, and video data. Support for acquisition data includes the input buffer, flash suppression, frame
average, and external ACQ memory. Cine buffer management is performed by the acquisition controller.
Conversion from acquisition data to raster data is performed by the graphics overlay, scan conversion
engine, sweeping engine, and 3D engine. Raster data is stored in an external DISPLAY memory. Also
supporting raster operations is the graphics support block that provides acceleration hardware for pixel
operations from the CPU and graphics overlay engine. Video data is processed as progressive scan and
supplied externally on a digital bus. In addition, interlaced video is supplied in both composite and S-video
formats. The progressive video path includes buffers, priority logic, and LUTs. External video in signals are
input and multiplexed onto the external video out path to allow for external sources to display information
on connected displays or printers.
28 Chapter 4: System Overview