EMG amplifier - help me to find suitable noise meter

Noise meter

Hi ,


I'm working on the EMG amplifier and I want to measure noise on my complete circuit(Preamplifier,filter,amplifier,...).

I found my Oscilloscope and voltmeter shy to measure my noise ,thier sensitivity are very LOW!!!

I want to find good circuit for NIOSE METER and bulid it my own.
I have some desgins (e.g. from Linear Technology and other) but i have prblem with LT1088.

Could you help me to find suitable noise meter ,please.
Please let me Know what can i do.

I'm witing for your reply
Best Regards.
Vahab(emglab@edaboard.com,biosignals@hotmail.com)

Re: Noise meter

Yeah, I grabbed some of those LT1088's before they went into extinsion. In my understanding, for EMG you need very low bandwidth, sub kHz measurement. I would use amplifers shown in those app notes and use decent rms meter. LT1088 will not do anything for sensitivity anyway.
You probably came across this , but just in case...

Noise meter

When you measure noise at an amplifier output, oscilloscope sensitivity usually isnt't too low. The first point is to have a defined criterion for noise measurement. To my opinion, either low frequency bandpass noise 0.1 to 10 Hz peak-to-peak or spectral noise voltage density would be appropriate measurements. The first measurement is easily achieved with a bandpass filter and an oscilloscope, for the second a tunable filter or FFT analysis is required. Auxilary amplifiers and a signal generator for level calibration are useful tools.

Generally, low frequency signal analysators, that cover the said measurements are available, but all necessary tools can be build from elementary OP circuits otherwise. Digital signal acquisition and processing can ease these measurements considerably.