Noise and Flatline

Start With The Simple Checks

Most first EMG failures come from power, electrode contact, ADC range, or wiring. Do not change the circuit until these are checked.

Flatline

If the waveform is a straight line:

1. Confirm the front end and acquisition board are powered.
2. Confirm the EMG output is connected to the correct ADC input.
3. Confirm ground/reference wiring is shared as required by the product version.
4. Check whether the ADC input range is too small or the signal is outside range.
5. Re-place wet electrodes and check skin contact.

Saturation Or Clipping

If the signal is stuck near the top or bottom of the range:

1. Check the output midpoint of the analog front end.
2. Confirm the ADC reference voltage and input mode.
3. Move away from chargers, monitors, and USB hubs.
4. Try battery power.

Strong Noise

If the waveform is noisy but still reacts to muscle contraction:

• Shorten loose wires.
• Keep the setup away from power adapters and displays.
• Use wet electrodes for the first test.
• Keep electrode contact stable.
• Check whether the reference electrode is placed correctly.

Success Signal

A usable first waveform does not need to look perfect. It should be quiet enough when relaxed and clearly larger during contraction.

If you can see that change, the signal chain is alive and you can improve noise step by step.