An inexpensive four channel demodulator for use in recording sleep biodata in the home environment

An inexpensive four channel demodulator was developed for use with our existing four channel FM recording system to acquire sleep biodata in the home environment. The demodulator uses four Phase Lock Loop (PLL) circuits for demodulation with capture frequencies selected from the standard IRIG Proportional-Bandwidth FM subcarrier frequencies. Four channels (EMG, EEG and two EOG) may be recorded for six hours at the subject's/ patient's home on a standard 7 1/2 inch reel audio recorder; it may be played back the following day through the demodulator and recorded on a standard laboratory polygraph for subsequent scoring and analysis. The portable home sleep recording system is inexpensive to build (our cost, excluding development, was $160.00); it would be useful to sleep researchers and clinicains interested in comparing sleep in the home versus sleep in the lab, and allows recording of sleep in patients who are reluctant or unable to have their sleep recorded in a laboratory setting.