Data Flow Control Description - GE Voluson E Series Service Manual

Components and Functions (Theory)

5.1.3 Data Flow Control Description

This section describes the functions of the boards vs. different operation modes.
•
RFM - (RF-Interface & Beamformer) FE Mainboard
•
RSX - (Beamformer Receiver/Transmitter) Extension Board
•
RTV - Video Management Board
5.1.3.1 B-Mode
1. IF-FPGA
The RFM contains the Clock-Management and PRF-Generator. It generates (drives) Shot-Trigger for
the BF-FPGAs. Configures the BF-FPGAs of RFM and RSX with Tx-Frequ, Tx-Focus, Rx-Focus,
LineNo (lateral Position), Tx- Apodisation, RX-Apodisation, Multibeam, etc.
Furthermore it contains Multibeam-DeInterleave, Subtraction Filter (for HI-Mode, see
"Special B-Mode Techniques" on page 5-10
LowPassFilter and Decimation (Pixel rate Conversion).
After DC-cancelling the signal is mixed with RX-Frequency and brought to LF-Spectrum, where the
LowPassFilter cuts HF. Mixer and Magnitude-Calculator arrange Complex Demodulation, and
Logarithmic Amplifier arrange the conversion from High-Dynamic LinearSignal to the Low-Dynamik(e.g.
8Bit) Log-Signal. Several postprocessing steps (LineFilter, FrameFilter, ReSample, Edge Enhance)
enable smooth image quality while keeping contrast high.
a. Direct Memory Access (DMA) section
B-mode data from RFM is written via Signal Processor (SP) Channel 0 into SDRAM Fifo Buffer
memory. DMA Controller 0 transfers the data into PC main memory where scan conversion is
performed per software. Cine Mode: Reserved area in PC main memory is used.
2. BF-FPGAs
Each BF-FPGA handles Rx/Tx of 64 channels. It controls 16 Tx-pulsers and 8 AFE ICs (i.e.: 32 Tx-
pulsers and 16 AFE ICs each on RFM and RSX board).
The AFE consists of Low Noise Amplifier (LNA), Rx-TGC-Amplifier, Signal-ADC. Each pulser can
support 4 Tx-channels, each AFE can support 8 Rx-channels.
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Tx-channel: The BF-FPGA generates Tx-Freq through dividing 200MHz by 2,3,4,5,... and Tx-
Focus.
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Rx-channel: The clock distribution generates Sample-Clocks for the ADC (50 MHz). The BF-
FPGA manages Rx-Focus (Delay and Chain-Adder) and Apodization.
3. RTV - Video section
Video Information is provided by the PC on the DVI (Digital Visual Interface) output connector. The
signal is connected to RTV, where the analog VGA signals for the monitor and standard video timing
outputs are generated.
5.1.3.1.1 Special B-Mode Techniques
1. HI (Coded Harmonic Imaging): In one method of HI the RX-Frequency is doubled, so that the radial
resolution is increased due to the higher RX-Frequency. The second method of HI is pulse-inversion,
that is handled by software: 2 TX-Beams are shot to the same Tissue-location, one with positive, one
with negative polarity. The subtraction of both shots (Subtraction Filter) brings to bear the nonlinear-
echo-reflection-properties of the tissue (especially in usage of Contrast-medias), which is very useful
with extremely difficult-to-image patients.
FFC (Frequency and Focus Composite): 2 or more TX-Beams are shot to the same Tissue-location.
2.
The Beams have different TX-foci. By means of Blending (adaption of Brightnesses) they are
composed to one whole RX-Line.
XBeam CRI (CrossBeam - Compound Resolution Imaging): Does not need any special functions of
3.
RFM. Image is composed of more than one different-direction-steered images. PC-calculated.
4. VCI (Volume Contrast Imaging): Does not need any special functions of RFM. Image is composed of
more than 2 small angle neighbored images. PC-calculated. (Only possible with 4D-Probes).
5-10
, DC-Canceler, Mixer (Part of Demodulator),
Section 5.1.3.1.1
Voluson E-Series Service Manual
5539550APB Revision 6