Choose MAT to save the recording as a .mat file for analysis in MATLAB. The output is saved beside the original recording with the same name and a .mat extension.
File contents
The file contains sensor measurements, navigation results, and status information. Each measurement is stored as a named column of values in recording order. Corresponding rows represent the same recorded sample.
The field reference lists the MATLAB names, descriptions, and units. For example, sys_time_s is time since the Hub was turned on, ins_roll_deg is aircraft roll in degrees, and ins_alt_msl_ft is altitude above mean sea level in feet.
MATLAB output includes the detailed measurements and status information available in Full CSV. Pilot name, tail number, aircraft type, and serial number are not included in the MATLAB file.
Status information
All values are numeric, including status fields:
| Field type | Meaning |
|---|---|
| Measurement | A value in the units listed in the field reference. |
| Yes/no status | 1 means true; 0 means false. |
| Battery status | 0 = low, 1 = warning, 2 = okay. |
| AOA type | 0 = angle in degrees; 1 = pressure ratio. |
The recording includes startup and periods when sensors may have been disconnected or reporting a problem. The initialization, connection, and health fields describe these conditions. Some fields may contain zeros when no measurement was available; a zero alone does not confirm a valid reading. NaN indicates an unavailable numeric value.
Time information
sys_time_s gives elapsed time since the Hub was turned on, in seconds. Resolution is 1 millisecond (0.001 s) for Hub and 1 microsecond (0.000001 s) for Hub Plus. UTC date and time are provided as separate year, month, day, hour, minute, and second values.
On Hub, UTC fields come directly from the GPS receiver, and utc_s contains whole seconds. On Hub Plus, utc_s includes fractions of a second with microsecond resolution (0.000001 s). Hub Plus also supplies gps_week and gps_tow_s; GPS time of week has the same microsecond resolution.
Hub Plus synchronizes its clock to the GPS receiver’s one-pulse-per-second (PPS) signal and uses internal timing between pulses to timestamp higher-rate samples. Both UTC and GPS time of week come from this synchronized clock. utc_time_initialized and gps_time_initialized indicate when each time reference is available. Hub recordings do not supply these additional clock fields, even if their names appear in the export.
Analog inputs
When supported by the recording, each analog channel includes its measured voltage and calibrated sensor reading. The calibrated reading’s units depend on the channel setup.
Hub recordings with external analog modules also include connection, battery, temperature, and health information. Hub Plus recordings include all four onboard channels and information about their assigned controls and calibration types.
For Hub Plus, the control assignment uses these values:
| Value | Control |
|---|---|
0 |
Elevator |
1 |
Aileron |
2 |
Rudder |
3 |
Throttle |
4 |
Mixture |
5 |
Prop |
6 |
Flaps |
7 |
Custom |
For channel 0, the names are ain0_volt, ain0_val, ain0_control_type, and ain0_cal_type. Channels 1–3 follow the same naming pattern. A control or calibration type of -1 means that information was unavailable in the recording.
The calibration type (ain0_cal_type through ain3_cal_type) uses these values:
| Value | Calibration type | Calibrated output range |
|---|---|---|
0 |
Two-point | 0 to 1. |
1 |
Three-point | -1 to 1, with the calibrated center at 0. |
-1 |
Unavailable | The recording does not provide the calibration type. |
Hub Plus calibrated values represent normalized control positions, not angles in degrees. All four onboard analog channels are included.