SECTION III PRINCIPLES OF OPERATION
- 3-7 -
3.1.2
The A-2000 Monitor
The A-2000 monitor contains the circuits for digitally processing the EEG data, computing
the processed parameters, and displaying the waveforms and processed parameters.
The circuits for acquiring the EEG signal and digitizing them reside in the digital signal
converter (DSC).
The monitor also contains the circuits for powering the monitor, DSC, and companion
printer. Printer function is not available on battery backup.
A block diagram depicting the monitor subassemblies appears in Figure 3-1. A signal flow
diagram appears in Figure 3-2. The signals are acquired and digitized by the DSC. The
DSC multiplexes the signals onto the DSC communications line. The EEG signals are de-
multiplexed in the monitor and fed to the Digital Signal Processor (DSP). The processor
filters and down-samples them, calculates the processed parameters, and outputs the
data display.
3.1.2.1 The Main Board
The Main board contains the Digital Signal Processors, the Host processor, data memory,
real time clock, and DSC interface.
All software and firmware can be downloaded through the serial port.
3.1.2.2 Digital Signal Processor
The functions of the DSP include: decimation filters for up to 2 channels of EEG data,
computation of processed EEG parameters, control of the DSC, and interface with the
host.
3.1.2.3 Host Processor
The functions of the host processor include: control of the display, interface with the
keypad, serial port, and printer, control of monitor boot up and download, control of
memory.
An on board annunciator is included for generating alarm sounds.
The display interface is a 4-bit LCD type.
The serial port is standard RS-232.
The printer interface is a non-standard serial type with extra lines for printer keys and
printer control and status. It is designed to interface with a Seiko printer interface board.
3.1.2.4 The Digital Signal Converter (DSC) Interface
The DSC interface is composed of two unidirectional bi-phase encoded serial lines, one
going to the DSC and another bringing data from the DSC.
The power to the interface is under software control. An overcurrent detector circuit
monitors current to the DSC. If the current exceeds the expected value, the power is shut
off to the DSC by the hardware, and the DSP is notified.
Summary of Contents for BISPECTRAL INDEX A-2000
Page 9: ...SECTION I INTRODUCTION 1 4 Figure 1 1 The A 2000 BIS Monitoring System...
Page 11: ...SECTION I INTRODUCTION 1 6...
Page 19: ...SECTION III PRINCIPLES OF OPERATION 3 2 Figure 3 1 The A 2000 System Block Diagram...
Page 20: ...SECTION III PRINCIPLES OF OPERATION 3 3 Figure 3 2 The A 2000 Signal Flow Diagram...
Page 35: ...SECTION V PREVENTIVE MAINTENANCE CARE AND CLEANING 5 6...
Page 53: ...SECTION VI DIAGNOSTICS AND TROUBLESHOOTING 6 18...
Page 61: ...SECTION VII DISASSEMBLING AND REASSEMBLING THE A 2000 7 8 Figure 7 4 The Four Mounting Screws...
Page 91: ......