Block diagram Description

Block diagram Description
The Figure shows Block Diagram of patient monitoring system. As name indicates the project is related to biomedical Instrumentation.Different blocks are explained as follows:-

PULSE MEASUREMENT
The sensor consists of a light source and photo detector; light is shone through the tissues and variation in blood volume alters the amount of light falling on the detector. The source and detector can be mounted side by side to look at changes in reflected light or on either side of a finger or earlobe to detect changes in transmitted light. The arrangement consist of an infra red light emitting diode and a matched photo detector.

ROOM TEMPERATURE MEASUREMENT
Here sensor used for temperature detection is Lm 35 which is precision integrated temperature sensor whose output voltage is linearly proportional to Celsius temperature.
The signal sensed from this IC is signal conditioned & send to microcontroller for display on screen.

Fire detector
To detect the temperature rise due to fire, a thermistor is used as sensor. The reason for using thermistor is the steep rise in resistance with rise in temperature.







EMERGENCY DIALLING
When Pulse rate is abnormal the microcontroller directly dials a set telephone number. Telephone Dialing is accomplished using relay transistor logic. The message is stored in voice recorder IC which is called upon by microcontroller in emergency situation and sent to concerned person through telephone line.

LCD DISPLAY
LCD 2 x 16 line decoder display is used for displaying various messages from sensors like pulse rate, Temperature.

MAX 232
The MAX220–MAX249 family of line drivers/receivers is intended for all EIA/TIA-232E and V.28/V.24 communications interfaces, particularly applications where ±12V is not available. These parts are especially useful in battery-powered systems, since their low-power shutdown mode reduces power dissipation to less than 5µW. The MAX225,MAX233, MAX235, and MAX245/MAX246/MAX247 use no external components and are recommended for applications where printed circuit board space is critical.
1. Superior to Bipolar
2. Operate from Single +5V Power Supply
3. +5V and +12V—MAX231/MAX239
4. Low-Power Receive Mode in Shutdown
5. Meet All EIA/TIA-232E and V.28 Specifications
6. Multiple Drivers and Receivers
7. 3-State Driver and Receiver Outputs
8. Open-Line Detection (MAX243)