GE M
EDICAL
S
YSTEMS
PROPRIETARY
TO
GE
D
IRECTION
2294854-100, R
EVISION
3
LOGIQ™ 9 P
ROPRIETARY
M
ANUAL
Chapter 5 Components and Functions (Theory)
5-15
5-3-4-2
Basic Functions
•
Compensates for the attenuation of the transmitted signal in tissue by depth: performs TGC based
on focal zone.
•
Compensates for frequency shift (TFC) in tissue, needed in B-Mode and M-Mode.
•
Filters out harmonics and optimizes signal to noise ratio.
•
Delivers amplified and corrected I & Q data to the BMP and the Scan Control Board.
•
Interfaces probe detection and probe ID signals between the XDIF and the host.
•
Controls transducer commutator (multiplexer) for muxed probes with more elements than channels
in the beamformer.
•
Monitors active probe temperature.
•
Masters the front end (FE) I2C busses for voltage and temperature monitoring.
•
Turns off PHVP on the cardrack power supply if a TD board pulls too much power or malfunctions.
5-3-4-3
Data I/O
The EQ signal input shall be two’s complement I and Q data busses input from the final summer of the
beamformer. The EQ I and Q inputs shall be 24-bits wide each, including the sign bit. The EQ outputs
shall be 16 bits wide each, including the sign bit.
5-3-4-4
Control I/O
Scanning control shall be provided by the scan bus. Configuration control shall be provided by a PCI
bus.
Timing control shall be provided such that all range dependent functions modify data at the correct
range. This requires two programmable delays times: analog delay, and digital delay. The range
dependent sfunctions include TGC, and TFC.
5-3-4-5
Analog Delay
The EQ use a programmable “analog delay” to time the start of TGC generation from TXSYNC (the start
of transmit). This will be set according to the time from TXSYNC until range 0 echoes arrive at the phase
center channel analog TGC amplifiers. Latencies will be considered when setting this analog delay to
insure that the analog gain is applied to the received signal for the intended range.
5-3-4-6
Digital Delay
The EQ uses a programmable “digital delay” to time the application of all range dependent functions on
the EQ. This will be set according to the time from RXSYNC (the beginning of a receive vector) until
range 0 echoes arrive at the EQ input. Normally this will be set to zero since vectors usually start with
range 0; however, virtual apex vector normally start vectors on a curved surface above the actual range
0.
The EQ shall additionally delay all range dependent functions equal to the relative delay of the data, to
insure that the range dependent data and functions are aligned.
5-3-4-7
Modes of Operation
The VEQ signal processing shall support two modes of operation: 10 MHz left only, and 5 MHz
interleaved left/right. In the 10 MHz left only mode the I/Q data will represent a single (left) beam
sampled at 10 MHz. In the 5 MHz interleaved left/right mode, the I/Q data will contain samples for a first
beam (left) interleaved with those of a second beam (right), where each is sampled at 5 MHz.
These modes of operation will normally be associated with different display modes. The 10 MHz left
only mode will most commonly be used for 2D B or M-mode. The 5 MHz interleaved left/right will most
commonly be used for colorflow, and the 5 MHz left only, for Doppler.
