Understanding the ECG quality

Hexoskin provides quality assessment channels that allow you to assess the ECG quality of your records. To decipher the code used to evaluate the signal quality of the RR intervals, please refer to "heartratestatus" in the API documentation. Please note that the API will provide you with hexadecimal values for the quality of the signal, and each of those has a specific meaning in terms of quality.

ECG status API - quality signal

As you can see in the section "Bits description", it shows that:

0x00 = the signal was of good quality

0x02 = the shirt (ECG sensor) was disconnected (decimal value of 2)

0x04 = the 50-60Hz noise was dominant in the ECG signal (decimal value of 4)

0x08 = the ECG signal was saturated (decimal value of 8)

0x10 = the ECG signal was affected by movement artifacts (decimal value of 16)

0x20 = there are some unreliable RR intervals in the ECG signal (decimal value of 32)

0x06 = combination of the disconnected shirt (ECG sensor) + the dominant 50-60Hz noise in the ECG signal (decimal value of 6)

0x14 = combination of the dominant 50-60Hz noise in the ECG signal + the ECG movement artifacts (decimal value of 20)

0x18 = combination of the saturated ECG signal + the ECG movement artifacts (decimal value of 24)

Please note that overall, if your quality signal is not 0, most likely, your ECG signal quality is quite low.

For signal quality data for the ECG signal, please open the "heart_rate_quality.csv" file of interest. Please note that when you download your record or activity, the .cvs files for quality assessment (_quality.csv) will not display hexadecimal values like the in API documentation (i.e. 0x00, 0x02, 0x04, etc.), but decimal values instead (i.e. 0, 2, 4, etc.).