What Is Biotelemetry?

Biomedical telemetry is mainly used for centralized monitoring of patients, long-distance measurement of physiological parameters of active objects, health management and in-vivo electronic diagnosis.

Patients are monitored centrally in the hospital to remotely measure the pulse, respiration, electrocardiogram, body temperature, blood pressure and other parameters of critically ill patients in order to detect changes in the condition in time and take emergency measures.

At this time, the sensor is firmly against the patient's skin, and the miniature encoder, modulator and transmitter are placed in the patient's clothes pocket. The sensor detects the patient's physiological parameters and transforms them into electrical signals, which are encoded, modulated, and sent to the medical duty room or medical center through the antenna. The signal received by the receiver is demodulated and decoded, and sent to the display to show the changes in the patient's physiological parameters for real-time monitoring, diagnosis and consultation by medical staff, and at the same time sent to the recorder for recording, for medical staff research and analysis Use.

Radio telemetry is commonly used in biomedical research to perform long-range measurements of physiological parameters of moving objects. For example: observe the electrocardiogram of patients with heart disease during exercise, study the changes in physiological parameters of people during physical activities and labor, and observe the physiological conditions of precious animals when they are in the wild. At this time, the sensor on the transmitting end is placed on the measurement site of the living organism, and the other devices on the transmitting end are placed on the part that does not affect its activity.

Use telemetry to observe the physiological parameters of workers under severe conditions (such as high temperature, high pressure, noise, vibration, shock, acceleration, etc.) in order to strengthen labor protection measures.

For example, a deep-water diver who works under high pressure should constantly monitor his physiological parameters such as electrocardiogram, pulse, and breathing. Once abnormal, he can be rescued in time. In this case, the water

Miniature endoscopes swallowed into the body can measure physiological parameters in the body, such as body temperature,

This instrument can perform real-time telemetry, display 6 people's electrocardiograms at the same time, can alarm the abnormal heart rhythm, store and resend the electrocardiogram within 4 to 6 seconds (if equipped with a cassette digital tape drive, can record and resend the entire electrocardiogram), And can perform wired monitoring on 2 people. The working distance of this instrument is 100 meters, and the heart rate display number is 3 digits. The entire instrument is divided into two parts, the sending end and the receiving end. There are sensors, shaping circuits, modulators and transmitters at the transmitting end. The receiving end has a receiver, a 6-channel roving sampler, a 10-fold frequency multiplier, a heart rate alarm, a record repeater, and a display.

The sensor is an electrode, which is placed on the skin of the patient's body near the heart. When the heart beats, an electrocardiographic signal of about 1 millivolt is generated, which is transmitted to the skin surface through the human muscle, and then output by the sensor and amplified to about 1 volt. The voltage waveform output by the sensor is shaped by a shaping circuit. The shaping circuit outputs a pulse with a constant amplitude, and its width is consistent with the ECG signal width.

This instrument has 6 transmitters, ^{[2] with different} carrier frequencies, ranging from 110 to 130 MHz. The pulse output by the shaping circuit modulates a 1-kHz square-wave subcarrier, and then modulates the carrier and sends it out. The transmitter power is only a few milliwatts, and it uses a 9 volt laminated battery as a power source, which can be carried around. The receiver uses a super-heterodyne receiver. After mixing, it uses the characteristics of different carrier frequencies and different intermediate frequencies to perform frequency division. The signal obtained by frequency division is amplified and discriminated to output a 1 kHz square wave subcarrier signal modulated by the ECG pulse. After the second demodulation, the ECG pulse baseband signal is output. Low-pass filter.

The 6-channel roving sampler enables one terminal device to process 6 sets of parameters. A 10-fold multiplier increases the heart rate by a factor of 10 to increase measurement speed. If tachycardia, bradycardia, arrhythmia, ventricular pause, and QRS 0.12 seconds occur, the heartbeat alarm will alarm. The monitor is used to display the ECG in real time, and the recorder is used to record the ECG for doctors' diagnosis and reference.