bioinstrumentation system provides an amplified electrocardiograph
analog signal from either of two designated flight crew members
to the orbiter avionics system, where it is converted to digital
tape and transmitted to the ground in real time or stored on tape
for dump at a later time. The designated flight crew members wear
the OBS during the ascent and entry phases. On-orbit use will be
limited to contingency situations.
The OBS electrodes
are attached to the skin with electrode paste to establish electrical
contact. The electrode is composed of a plastic housing containing
a non-polarizable pressed pellet. The housing is attached to the
skin with double-sided adhesive tape and the pellet contacts the
skin. There are three electrodes on the harness marked LC (lower
chest), UC (upper chest) and G (ground).
The ECG signal
conditioner is a hybrid microcircuit with variable gain (adjusted
for each crew member before flight). It provides a zero- to 5-volt
output and has an on/off switch within the input plug, which is
actuated when the intravehicular activity biomed cable is plugged
in. The unit has batteries that will not be replaced in flight.
The IVA biomed
cable connects to the signal conditioner and is routed under the
IVA clothing to connect to the biomed seat cable. The biomed seat
cable is routed to one of the biomed input connectors located on
panel A11, A15 or M062M. Rotary control switches on panel R10 provide
circuits from the biomed outlets to the orbiter's network signal
processor for downlink or recording. The two rotary switches on
panel R10 are biomed chan nel 1 and channel 2 . Extravehicular activity
positions provide circuits for the EVA UHF transceiver.
application kit contains components to aid in the application of
electrodes. The components include wet wipes, double-sided adhesive
tape, overtapes, electrode paste and a cue card illustrating electrode