Here is a short description of the metrics contained in the csv data files exported from the study portal. You can refer to these articles to learn how to export data from the portal and what are the different data types.
Raw data files
In each raw data file, the first column contains a Unix timestamp in milliseconds and the second column shows the corresponding date and time in a readable text format.
PPG files
CardioWatch 287-2B
The color of the LED appears in the name of the csv file. It can also be derived from the metric_id column:
| Metric ID | LED |
|---|---|
| 0x7e | green |
| 0x7c | red |
| 0x7b | infra red |
| 0x7f | ambient |
The value column gives the output value of the PPG sensor, comprised in the range [0; 65535]. The led and gain columns give the LED power and gain applied during the measurement. The LED power is a percentage, and the gain is a factor between 1 and 3.
CardioWatch 287-1B
This file contains the following metrics:
| Vital Parameter | Column name in csv file | Unit |
|---|---|---|
| PPG | ppg | PPG green sensor value |
| Accelerometer | acc accx accy accz | Magnitude of the acceleration Value of the X-axis, in 1/64 g Value of the Y-axis, in 1/64 g Value of the Z-axis, in 1/64 g |
| Pulse rate | bpm bpm_q | Number of beats per minute Quality level from 0: very low to 4: very good |
The magnitude of the acceleration is computed as follows:
acc = sqrt( accx2 + accy2 + accz2 )
The sampling rate for both PPG green and accelerometer sensors is 25 Hz.
ECG file
The ecg column gives the output value of the ECG sensor in mV. The sampling rate is 256 Hz.
This file is not supported for 287-1B.
ACC file
The accX, accY and accZ columns give the output values of the 3-axis accelerometer, in the unit of 1/512 g. The accelerometer is configured to measure acceleration in the range of [ -8 g; +8 g ].
Note that for the CardioWatch 287-1B, the accelerometer data are exported in the PPG file.
BioZ
The value column represents the output of the calibrated sensor, which is a conductance value expressed in the unit of 100 picosiemens. The sampling rate is 25 Hz.
This file is not supported for 287-1B.
Vital parameters files
In each data file, the first column contains a Unix timestamp in milliseconds and the second column shows the corresponding date and time in a readable text format.
Activity
The activity file contains a summary of many metrics provided by the CardioWatch system, as well as some information regarding the bracelet status. Here are the main ones.
| Vital Parameter | Column name in csv file | Unit |
|---|---|---|
| Pulse rate | bpm bpm_q | Number of beats per minute Quality level from 0: very low to 4: very good |
| Respiration rate | respiration_rate resp_q | Number of breaths per minute Quality level from 0: very low to 4: very good |
| SPO2 | spo2 spo2_q | Pulse oximetry in % Quality level from 0: very low to 4: very good |
| Steps | last_steps activity_type | Number of steps Type of activity: 0: unspecified, 1: other, 2: walk, 4: run, 6: cycle, 7: rest |
| Energy | energy_exp | Total energy expenditure in cals |
| Bracelet status | Column name in csv file | Unit |
|---|---|---|
| Battery level estimate | battery | Battery level in % |
| Wearing status | wearing | From 0: not wearing bracelet to 4: wearing bracelet |
RR intervals
The rr column shows the interval between successive peaks of the heart beat in millisecond.
Workout
The workout file contains the data associated to workout sessions. Some of the fields are identical to those of the activity file (see Activity section above). Additional information might be available, depending on the type of activity selected by the user and the session duration.
| Parameter | Column name in csv file | Unit |
|---|---|---|
| VO2 max | vo2_max | mL/kg/min |
| Cardio fitness index | cfi | From 1 to 100 |
| GPS | gps_lat gps_lon gps_speed | GPS coordinate latitude GPS coordinate longitude GPS estimated speed |
Sleep
The sleep_state column gives the sleep state and the sleep_q column shows the quality factor associated to this state. Here are the different sleep stages corresponding to the states: 1: awake, 2: light sleep, 3: deep sleep, 4: REM sleep.
Temperature
| Parameter | Column name in csv file | Note | Unit |
|---|---|---|---|
| Temperature | temp_sk1 temp_sk2 | All day long, 287-2B only Only at night | °C °C |
EmoGraphy
| EmoGraphy metric | Column name in csv file | Range |
|---|---|---|
| Stress level skin conductance | stress_skin stress_skin_quality | 0 to 1000 0 to 4 |
| Cognitive zone | cz | 0 to 3 |
| Predictive cognitive zone | pcz | 0 to 3 |
| Predictive cognitive zone time | pczt | Time in minutes |
| Cognitive zone in one hour | czh | 0 to 3 |
| Cortisol contribution | cc quality | NA 0 to 4 |
Please refer to the EmoGraphy article for further information.
This file is not supported for 287-1B.