Noise floor testing
| Amplifier | Inputs shorted (μV rms) | Connected by 1 kΩ (μV rms) | Connected by 10 kΩ (μV rms) | Connected by 10 kΩ and 30-cm cable (μV rms) | Inputs open (μV rms) |
|---|---|---|---|---|---|
| OpBox A | 1.322 ± 0.005 | 1.324 ± 0.009 | 1.337 ± 0.008 | 1.342 ± 0.006 | 1.708 ± 0.011 |
| OpBox B | 1.282 ± 0.006 | 1.284 ± 0.006 | 1.297 ± 0.006 | 1.306 ± 0.007 | 1.896 ± 0.021 |
| Grass | 0.554 ± 0.009 | 0.596 ± 0.046 | 0.589 ± 0.008 | 0.529 ± 0.018 | 12.756 ± 0.122 |
| Intan | 2.632 ± 0.009 | 2.708 ± 0.046 | 3.032 ± 0.055 | 22.107 ± 1.034 | 13.104 ± 0.508 |
Values from noise floor testing of the different amplifiers; 5-min segments of recordings were taken from each amplifier type with differential inputs shorted using a wire, connected using different resistors, or left completely unconnected. To mimic the effect of having EEG travel via a cable in a tethered subject recording, we also connected the amplifier inputs to a 10-kΩ resistor but at the end of a 30-cm shielded two conductor cable. The shielding of the cable was grounded. Mean RMS values of these 5-min segments were calculated using 10 non-overlapping 30-s windows. Mean and SEM values are reported for each combinations of amplifier type and testing criteria; n = 10 non-overlapping 30-s windows for all table cells.