A Multichannel Personal Telemetry System Using Pulse Position Modulation
AIR FORCE AEROSPACE MEDICAL RESEARCH LAB WRIGHT-PATTERSON AFB OH
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A personal telemetry system using the pulse position modulation technique has been developed. The laboratory model transmits heart rate, respiration rate, and body temperature within a range of 100 feet. Compared with FM - FM Systems this system has the advantage of very low power consumption 20 milliwatts, light weight 6 ounces with batteries for 80 hours continuous operation, small size 4-34 by 3-12 by 1 inches, and sufficient accuracy and stability 2 percent baseline stability for physiological measurements. An inexpensive, small, single-track tape recorder may be used for recording and an extremely simple and inexpensive playback system can be used for scope display. Although more complex equipment is required for the playback system to standard penwriters, this penwriter decoding unit is not any more complicated than standard FM discriminators. Simple, reliable, switching-type circuits which work over a wide temperature range are used, and there is no problem with crosstalk between channels. The limitations of this personal telemetry system are a the frequency capability for each channel is 0 to 40 cps b it is limited to a maximum of 6 channels and c special playback equipment is required.
- Anatomy and Physiology