Aspect BIS VISTA Spécifications télécharger pdf (Page 27)

SECTION 3 PRINCIPLES OF OPERATION

_______________________________

_______________________________________

3-5

Test Signal

A calibrated test signal is generated during the DSC Self Test. The signal is a 2 Hz square

wave of approximately +/-50µV. It is applied to the inputs of the differential amplifiers,

resulting in a test of the entire signal path except for the input connections and protection

circuits. During the Self Test, noise, gain and frequency response are checked.

Interface to the Monitor

Output from the two channels are multiplexed in a field programmable gate array (FPGA).

Multiplexed with the EEG data is status information such as BISx identification,

“lead off” indication, and power supply faults.

The BISx decodes the control information coming from the monitor via a command line.

Commands such as “block” amplifier saturation and conduct impedance tests are

transmitted.

BISx Power Supply (Patented technology)

The BISx derives power from the monitor. Power supply circuitry produces the necessary

voltages for operation. Power for patient-connected circuits is provided through a

transformer. These circuits are isolated for patient safety.

3.2.1.4 The BISx Mechanicals

The BISx is contained in a small custom designed plastic case (see Figure 4). It is connected

to the monitor via the Monitor Interface Cable and connects to the BIS sensor via the

Patient Interface Cable (PIC). Both cables are strain relieved. The cables and the BISx

Bulkhead Connector (used to attach the PIC to the BISx) can be replaced, if necessary, by

the user. The attachment clip on the back of the BISx may be used to secure it to a

convenient location near the patient’s head.

There are no ventilation holes in the BISx case. It will not leak when splashed with liquids.

The case is electrically shielded both to prevent spurious emissions from the BISx and to

prevent externally caused interference with the BISx circuits.

3.2.2 The BIS VISTA Monitor

The BIS VISTA monitor contains the circuits to enable the touch screen, to receive

processed parameters from the BISx, to display the data on the screen, and to communicate

with other devices via USB and RS-232 ports.

The monitor also contains the circuits for powering the monitor and the BISx. An on board

annunciator generates alarm sounds.

A block diagram depicting the monitor subassemblies appears in Figure 5. A data flow

diagram appears in Figure 6. The signals are acquired, digitized, filtered, and processed by

the BISx. The BISx multiplexes the signals onto the BISx communications line. The data are

de-multiplexed in the monitor for display.

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 93 94

Pas de commentaire

Aspect BIS VISTA Spécifications Page 27