his integer value provides an indication of how good or how poor the bio-signal is at the sensor. This value is typically output by all ThinkGear hardware devices once per second.
This is an extremely important value for any app using ThinkGear sensor hardware to always read, understand, and handle. Depending on the use cases for your app and users, your app may need to alter the way it uses other data values depending on the current value of POOR_SIGNAL/SIGNAL_STATUS. For example, if this value is indicating that the bio-sensor is not currently contacting the subject, then any received RAW_DATA or EEG_POWER values during that time should be treated as floating noise not from a human subject, and possibly discarded based on the needs of the app. The value should also be used as a basis to prompt the user to possibly adjust their sensors, or to put them on in the first place.
This updated version converts poorSignal values read from different hardware devices. It converts them into a uniform format. (unlike earlier version of the SDK) If you have software that reacts to the poorSignal value, you should evaluate that software to see if changes need to be made
Poor signal may be caused by a number of different things. In order of severity, they are:
Sensor, ground, or reference electrodes not being on a person's head/body
Poor contact of the sensor, ground, or reference electrodes to a person's skin
Excessive motion of the wearer (i.e. moving head or body excessively, jostling the headset/sensor).
Excessive environmental electrostatic noise (some environments have strong electric signals or static electricity buildup in the person wearing the sensor).
Excessive biometric noise
For EEG modules, a certain amount of noise is unavoidable in normal usage of ThinkGear sensor hardware, and both NeuroSky's filtering technology and algorithms have been designed to detect, correct, compensate for, account for, and tolerate many types of signal noise. Most typical users who are only interested in using the eSense™ values, such as Attention and Meditation, do not need to worry as much about the POOR_SIGNAL Quality value, except to note that the Attention and Meditation values will not be updated while POOR_SIGNAL is greater than zero, and that the headset is not being worn while POOR_SIGNAL is higher than 128. The POOR_SIGNAL Quality value is more useful to some applications which need to be more sensitive to noise (such as some medical or research applications), or applications which need to know right away when there is even minor noise detected.