The system is presently being developed by Gennady Troschenko. It consists of the sensor unit fitted to the face (on the picture), connected through external amplifier/commutator to an IBM PC, whose sound card is currently used as a signal digitizer. Various “reality test” buttons can also be included. This system can pick up following signals:
- Oculogyration signals by detecting fine eye lids displacements – this is done by two photoelectric sensors. Good disturbance immunity has been achieved by high-frequency modulation of the signal, as well as software compensation, using difference in the signals coming from different eyes. Things like illumination changes have absolutely no influence upon the system.
- Jerk/motion/position signal , (comes from a tiny ball rolling inside a chamber, “watched” by photo sensors) – it reflects motor activity of the sleeping; can be calibrated to show position of the head.
- Sound signal from sensitive microphone.
- Signals for monitoring breathing, from two thermo sensors in front of each nostril.
- Amplifier also permits picking up of skin potential signals such as oculogram, EEG, or myogram, and skin contact resistance measuring (galvanic reaction).
These signals are processed and continuously displayed on PC monitor in form of crawling curves and other marks; they can be saved in a file for future study.
"Snapshot" from PC screen
The feedback from the system to the sleeping is currently confined to playing sounds and flashing diodes in various combinations, but some other stimuli can be tried, too.
Basically, the system is dialog oriented, i.e. it was designed for experiments in pairs – one person sleeping and the other one watching his state and trying to establish a contact of some kind. For this purpose two PCs are needed – one beside the sleeping’s bed , and the other one for the remote observer. Now the two PCs are located just in adjacent rooms and connected via serial ports, but we can see an exciting prospect of using modems and connecting them through phone lines, or even via Internet, which will permit really remote experiments.