GE HEALTHCARE
DIRECTION FC091194, REVISION 11 VIVID 7 SERVICE MANUAL
6 - 6 Section 6-7 - Front-End Alignment Procedure (Beamformer Calibration)
Section 6-7
Front-End Alignment Procedure (Beamformer Calibration)
6-7-1 Introduction
Each A/D converter on the BF boards has an offset error (i.e. gives an output code different from 00 Hex
with an input voltage of 0V). This offset error may cause artifacts in some modes of operation (2D and
TVI) due to inaccuracy in the demodulation process. In order to deal with this problem, the software has
support for cancelling of these offset errors. This is done by first reading the offset error and then
accounting for these numbers later during the normal processing.
Beamformer Calibration is performed to calibrate each ADC channel of the two Beam Former (BF)
board inputs. The system calibrates the Beamformer ADCs to zero output when there is no signal on
the input.
These bias voltages are stored on hard disk in Back-End Processor.
The Front-End Alignment procedure can be performed either as described below, or via the GSUI.
See: 7-6-7 "Calibration" on page 7-33.
6-7-2 When to Use this Procedure
This procedure should be performed;
• when installing a new Vivid 7
• after software has been updated or replaced
• when BF boards have been interchanged
• when a BF board has been replaced
• when the Back-End Processor has been replaced
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