Block Diagram of Biotelemetry system

Block Diagram of Biotelemetry system:

The transducer converts the biological signal from Patient into electrical signal. The signal conditioner amplifies and alters this signal for efficient transmission. The transmission link connects the signal conditioner to the read out and monitoring device by wire or wireless means.

Major Specifications of a Bio Telemetry System:

a. The telemetering system must be selected to send out the bio-electric signals with maximum reliability and ease and directivity.
b. There would not be any discomfort for living system due to these telemetry systems. In any condition the natural living environment of the living system should not be affected.
c. The size and weight of telemetry system should be small and should not be too costly.
d. It should have more stability and reliability and efficiency.
e. The power consumption should be moderate.
f. The presence of common mode noise will affect the measured physiological variable. So at the transmitter side differential amplifier must be present to reject this component.
g. For wire transmission the cable should be shielded well to avoid noise and Electro Magnetic Interference (EMI).
h. In the case of long term units or implant units the weight and of the telemetry system must be designed in a way such that the system should be comfortable to the subject.
i. There should be any interference with living system.

Biotelemetry Transmitter Block Diagram:

Mobile units close to the patient comprises of a transmitter. The physiological variables are measured using a transducer (ex: Temperature, pressure etc) and the bioelectric signals are directly measured using suitable electrodes. The measured variables are then suitably amplified and processed and given to the modulator circuit. The physiological signal modulates a sub-carrier in audio frequency range. The sub-carrier in turn adapts the RF signal to be spread and sent to the transmitting antenna. The sub carrier is modulated moreover by AM or by FM techniques. But usually FM technique is used.

Biotelemetry Receiver Block Diagram:

The receiver consists of a tuner, demodulator, and a display unit. The receiving antenna receives the multiplexed RF carrier which was transmitted by the transmitting antenna. The tuning circuit is properly tuned to receive the appropriate signals and the unwanted signals are rejected. The receiving antenna must have high selectivity. The multiplexed RF carrier is demodulated to improve the individual sub carriers from which original physiological signals can be decoded. The recording system is used to record the physiological variables either in a chart paper (ECG, EEG etc) or in a display unit (Computer, monitor, oscilloscope etc.). The signals can be stored on any secondary storage media such as magnetic disk.

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