Occurences of Repeated Spaced Noise
Hi, I've been experimenting with some new electrode designs and currently with some standard basic pieces I'm testing, I've been seeing these instances of noise, but what confuses me is how predictable they are in spacing and shape. I don't think the source is external as I have notch filters for AC mains and the noise from plugged in devices tends to be much more erratic. I'm currently using a Ganglion.
Initially, I thought it was some interference from the body, but I find I can reproduce this noise by simply leaving the electrodes placed on the desk. Spacing two differential electrodes far apart seems to cause this. Placing the two electrodes closer together or twisting their wires together completely eliminates the noise, and as far as I can tell the driven ground electrode has no effect on this specific noise. The issue is that even with twisted wires, the exact pattern reemerges when the electrodes are placed on skin.
I've noticed two main kinds of signal noise patterns. One is a consistent action potential-like signal that occurs at a rate of once per second. The other is a burst of high-frequency inconsistent noise that occasionally randomly intermixes with the repeated noise signal. These two noise patterns almost always occur together.
Pictured below is the repeat signal in 5 and 10 second intervals.
Pictured below is the burst signal in 5 and 10 second intervals.
Any idea what could be the cause or source of this particular noise?