23-10-2010, 09:53 AM
Heart Rate Monitor
Abstract
The aim of this project is to implement an ECG and Digital Heart Rate counter. amplifying
the desired weak signal from the heart and isolating this from the noise signal from the
muscles were the main challenges. A display of the heart rate will also be implemented.The
time between signal peaks will be calculated and then the frequency of the peaks will be
obtained. Attempt is made to make the device portable. low cost amplifier and filter
components were used and it also includes the microcontroller and LCD screen.
Design
The main challenge is to amplify the desired weak signal in the presence of noise from other
muscles and electrical sources.
Desired signal
the range of about ~2mV is the voltage range picked up by the electrodes at the skin
surface.
Noise
External interferences like 50Hz from power lines and emf’s from fluorescent lights will
affect the picked up signal. Muscles other than the heart also produce voltage potentials.
Block diagram
The major blocks in this project are
1)amplifier and filter
2)ADC
3)Microcontroller
4)Display
5)Clock
6)Voltage regulator
7)Battery
Amplification Stage
An instrumentation amp of high gain and high Common Rejection Ratio (CMRR) is used to
amplify the weak signals.
Processing & Display
the output signal produced by the amplification stage is processed by an 8 bit
microcontroller. Microchip PIC16F877A microcontroller is used. An liquid crystal display
(LCD) module is used to display the beats.
Power
9V battery is used to power the circuit. The required 5V is obtained via a LM7805 5V voltage
regulator.
Get the report here:
http://engnet.anu.edu.au/DEpeople/Salman...ng/TA1.pdf
also see these:
http://bioengineering.gmu.edu/SeniorDesi...0/IHRM.pdf
http://engineering.verniergeneral/projec...-with-led/
