GE FK000040, Руководство по обслуживанию

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GE M
EDICAL
S
YSTEMS
D
IRECTION
FK091075, R
EVISION
04 V
IVID
3N P
RO
/E
XPERT
S
ERVICE
M
ANUAL
Chapter 5 Components and Function (Theory) 5-21
Both input addressing (start and length) and output addressing (through output events) are controlled
by the RFI board itself.
5-4-7-6 Tissue Processing
A number of different tissue processes are performed on the RFI board:
1.) Firstly, the signal amplitude is obtained by detection .
2.) Then the data is compressed to attenuate the strong signals and amplify the low level echoes.
3.) After compression, Zone Stitching is performed. Zone Stitching is used to combine the (transmit)
focal zones from different vectors into one vector by weighting the zone transitions, and only applies
to phased/linear array probes where multiple vectors can be collected in the same direction.
For M-Mode, peak detection and edge enhancement is implemented.
4.) Finally, in some cases, an offset can be added to the signal and clipping is performed.
5-4-7-7 Color Flow Processing
No Color Flow processing is performed here, except for the RF demodulation previously mentioned.
The data used for Color Flow is tagged with the appropriate headers and tails and sent to the Back-End
Processor (BEP).
5-4-7-8 Doppler Data
On the RFI board, Doppler Data is high pass filtered (to remove strong low frequencies returned from
wall motion, valves and leaflets) and then sent to the BEP, and to Audio Circuitry on the KB Control
Board.
5-4-7-9 System Temperature Surveillance
The RFI board monitors the temperature in the airflow at the air intake, and in the airflow at the air outlet.
These measurements make it possible to monitor the environmental conditions (temperatures) for the
scanner and prevents overheating.
5-4-7-10 Probe Management
The RFI board performs the following probe management functions:
• Controls the selection of a probe connector
• Senses the Probe type
• Senses the Scan Plane Angle on MPTE and PAMPTE probes
• Senses the Probe temperature
• Turns OFF the probe if the temperature exceeds the maximum temperature. The temperature
references are set to 41.3
o
C and 43.0
o
C.
• Turns OFF the probe if the temperature reading falls below minimum temperature
The minimum temperature references is set to15
o
C. A temperature reading as low as 15
o
C indicates
a probe temperature-sensing error.
5-4-7-11 TX Power Supply Management
The TX Power supply has two separate voltage outputs, as follows:
• TX Power Supply #1 (TX1) - generates voltage levels for pulsed TX operations
• TX Power Supply #2 (TX2) - generates voltage levels for both pulsed and CW operations
The RFI sets the voltage level for the two TX Power Supply outputs (TX1 and TX2) and also measures
the voltage levels and current drain from the two TX outputs. If any of the values exceed the limit for a
given mode, the RFI will turn OFF power to the probe.