Will the accuracy of a sensor be degraded if it is out of calibration?
The calibration only effects the IMU so the main effect of being out of calibration is that when the system depends more in IMU outputs then it will be less reliable.
If you are operating in an area with good views of open skies—and therefore good GPS reception, the sensor’s velocity will be derived from the GPS signal. So if there is any degradation of the IMU due to the system being out of calibration, it is unlikely to have any significant effect on velocity measurements.
In areas where the GPS reception is not so good, you might see an effect on the measurements if the sensor is out of calibration, because the velocity measurements will be more heavily based on the IMU measurements—although it is impossible to quantify how much effect this will have. The level of degradation will continue to increase the longer the unit is left uncalibrated.
How do the basic and ISO calibrations differ?
The ISO calibration is essentially a more thoroughly documented and traceable process. A sensor calibrated using the ISO calibration is no more accurate than one calibrated using the basic service. Here are the differences with the ISO calibration:
- Accelerations and angular rates are traceable to national standards (though other measurements are not).
- A pre-adjustment assessment is provided.
- A calibration certificate including acceleration and angular rate measurements and uncertainties is provided.
- Additional management processes are used to conform to the requirements of ISO 17025.
- UKAS has audited and accredited OxTS—giving confidence to the measurements that we make.
- Background information is supplied (if required).
For more information check our brochure on the calibrations. Here are some examples of the calibration certificate you get with each: