GE MEDICAL SYSTEMS
D
IRECTION 2392751-100, REVISION 3VIVID™ 4 SERVICE MANUAL
Chapter 5 - Components and Function (Theory) 5-19
5-4-4 Beamformer Board (BF)
5-4-4-1 General Description
The Beamformer Board (BF Board) contains the A/D converter, the ASIC (called the Focuser [FOC])
and a Beam Adder (BA). The BF Board accepts input channels and converts each channel to digital
bytes.
The system requires one BF Board which scans 64 channels.
The digitized samples at the ADC output are input to the FOCs, whose outputs go to a BA. The output
of the BA (BA Level 2) is the sum of the input channels, which is added together with the output from
the other BA Level 2, as shown in Figure 5-13 on page 5-20.
These ASICs will add all the input and output channels, with appropriate delay, to give optimal receive
focusing and beam steering as a function of time. All focusing and steering parameters for a scan are
stored in VRAM on the BF Board. The output of the BF Board is a high-frequency digital Word update.
This output can be added to any successive board, if more channels are required.
•
BF Calibration: The system has a calibration procedure for the BF Board, which sets the offset
voltage for the ADC on the BF Board. If the BF Board is replaced, the calibration procedure has to
be performed, as described in Beamformer Calibration on page 6 - 14.
•
BF Board Location: The BF Board can be placed in the Front End Crate, in the third slot from
the left side.
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