Biotelemetry - Radio,single channel, Multi channel

Biotelemetry

1. Biotelemetry Radio Telemetry (single, multi ), Multiplexing of biosignals- FDM,TDM, Portable and Landline Telemetry unit, Applications in ECG and EEG Transmission

2. Biotelemetry is the measurement of biological parameters over a distance. i.e , Biotelemetry is defined as the transmission of biomedical signals and parameters to remote recorder by means that do not cause s ubstantial disturbances and restraints to the human being monitored.

3. DESIGN OF BIO TELEMETRY Telemetry system should be selected to transmit the bio –electric Signal with maximum fidelity and simplicity . The sysetem should not affect the living system by any interference. Smaller in size light in weight . It should have more stability and reliability . The power consumption at the transmitter and receiver should be small .   It should reject common mode interference rejection . Miniatured radio telemetry system should  be used to reduce noise.  

4. SINGLE CHANNEL BIOTELEMETRY

5. Single Channel Biotelemetry

6. MULTI-CHANNEL BIOTELEMETRY

7. Multiplexing is the process of simultaneously transmitting two or more individual signals over a single communication channel. due to multiplexing it is possible to increase the number of communication channels so that more information can be transmitted. Time Division Multiplexing and Frequency Division Multiplexing. The typical applications of multiplexing are in telemetry

8. Functional block of MUX and De-MUX

9. TIME DIVISION MULTIPLEXING

10. Most biomedical signals have low frequency bandwidth requirement, we can use time division multiple system by time sharing scheme. Transmission channel is connected to each signal channel input for a short time to sample and transmit that signal. Transmitter is switched to the next input signal channel in a definite sequence.   All the channels have been scanned once, a cycle is completed and the next cycle will start .

11. At the receiver the process is reversed. The sequentially arranged, signal pulses are given to the individual channels by using gate signal generator .   If the number of scanning cycles per second is large and if the transmitter and the receiver are synchronized, the signal in each channel at the receiver side can be recovered. But the scanning frequency has to satisfy the following condition.   fscan = 2fmax  

12. Time Division Multiplexing

13. FREQUENCY DIVISION MULTIPLEXING

14.    Each signal is frequency modulated on a sub carrier frequency.   Modulated sub carrier frequencies are combined to modulate the RF carrier .    At receiver the modulated sub carrier can be separated by the proper band pass filter.    Then the each signals are demodulated by using specified frequency.      Frequency of the sub carrier has to be carefully selected to avoid interference.      The low pass filter are used to extract the signals without any noise. Finally the output unit displays the original signal.  

15. Frequency Division Multiplexing

16. The IC 4051 is an 8-channel analog multiplexer/de-multiplexer with three address inputs (S0 to S2), an active LOW enable input (E), eight independent inputs/outputs (Y0 to Y7) and a common input/output (Z).

17. PIN DIAGRAM IC 4051