GE BRIVO MR355, Service Training, Page: 122 / 227

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The RF Amplifier Support Chassis (ASC) will house two complete Universal Power Monitors for
redundancy. A UPM will consist of a UPB and up to two UPM RF Detector Boards (RFD) connected on
the ASC Backplane. Each UPM will be capable of monitoring forward and reflected RF power in a MR
system for 0.35T to 3T range of field strengths. In 1.5T SV system, only forward RF power is monitored.
The RF Detector Board is the front end of the UPM. They accept coupled RF power from the various
transmitter pathways in the MR systems, and execute Analog to Digital conversion (ADC) under the
control of UPM Processor Board (UPB), and convert them to a digitized power envelope.
The digitized power envelope is passed along to the UPB to be processed through mathematical
algorithms for the monitoring of RF power levels and for the detection of excessive power conditions.
The UPB will communicate status and fault/error conditions to the system through CAN as well as
supporting inter-module communications as necessary.
In SV and HDe system, RF AMP Interface board (AMPIF) is introduced to support SRFD3. The AMPIF
receives NB UNBLANK signal from the Driver Module and passes these UNBLANK signal to the RFPA.
When RF Output Power is above the limitation, UPB will create RF LOCK signal and send it to AMPIF.
AMPIF will send RF LOCK signal to RFPA to stop power output. And UPB sends inhibit Unblank signal to
the Drive Module to stop output the Unblank signal.
Attention: The AMPIF for CAM Lite is basically compatible in function with the AMPIF in ASC Lite of HDe.
But the pin assignment of RF LOCK on backboard is different between ASC LITE and CAM Lite. They
would be compatible by switching the pin assignment by switch on the board.
Note: NB = Narrow Band, BB = Broad Band, CW = Continuous Wave, BB and CW Unblank signals are
only for Multi-Nuclear Spectroscopy (MNS) amplifiers.