I want to know :
can i obtain ECG leads(limb leads ) without using preamplifier or differential op amp ?
**broken link removed**
can i just measure [SUB](at the same time)[/SUB] three voltage of LL[SUB](left leg)[/SUB],RA[SUB](right arm)[/SUB] and LA[SUB](left arm)[/SUB] and using RR[SUB](right leg)[/SUB] as ground
and then in the computer the leads will be obtained mathematically by using a software ?
You´d first have to say what the supervisor actually wants and what is the goal of this assignement.
You say you can´t use instrumentation amplifier, does that mean you can´t use a signel chip that does the job, or you you can´t use any amplifier in the instrumentaion amp configuration? Also are you sure you are not mixing up instrumentation and differential amplifiers?
What can you use?
You say you can´t use instrumentation amplifier, does that mean you can´t use a signel chip that does the job, or you you can´t use any amplifier in the instrumentaion amp configuration? can?
Ok, but is this an excersise in electronics or in digital signal processing or in biology? And can you use a normal amplifier? Because there is no way that you can sample the waveforms without one.
Yes if you measure the three voltages referenced to the RR, then you should be able to get the three "leads" by substraction.
yes i can use normal amplifier,to amplify voltage of electrode
but the problem is :the voltage of electrode is about 1 Vp.p
so i can't use amplifier with gain more than 10
because the output signal will be high voltage(more than 10Vp.p), this can't measured by ADC.
The problem is that most of the signal you measure is 50hz noise (just tried with my oscilloscope ), and just a tiny bit is the useful signal, so you need to sample it with huge resolution to be able to substract those two in digital and get anything else but noise.
The practical method is that you substract the two signals from each other, it doesn´t get more practical than that.
i saw the electrode signal on oscilloscope ,it has 50Hz ,
but it even if 50Hz removed, the signal will be about 150mVp that mean it still has a lot of noise