Telemetry Design of a Vital Sign Recording System

Blood pressure, respiratory rate, body temperature, and pulse rate are vital signs that under certain pathological conditions require continuous monitoring. In this paper we present a novel design of a system that embeds these signals into a single waveform that can be transmitted without the need for time or frequency division multiplexing. The system depends on changing the frequency of a square wave oscillator. One signal with low frequency contents controls the On-time of the oscillator while the Off-time is controlled by another signal. The third and the fourth signals are used to control voltage controlled oscillators. The voltage controlled oscillators outputs are used as fluctuations during the On-time and during the Off-time. The main advantage of this system is the reduction in circuit complexity in both transmitter and receiver with accurate recovery of the transmitted signals. The design of the proposed system is presented in this paper along with all the corresponding simulations.