A sensor device for attachment to a cargo transportation unit, CTU, the sensor device comprising: a sensor ; a communication interface to communicate over a network ; and at least one processor configured to: receive a calibration parameter through the communication interface in order to calibrate the sensor, the calibration parameter transmitted by a remote service over the network, modify an operating characteristic of the sensor based on the calibration parameter, wherein the operating characteristic is a signal strength of a signal emitted by the sensor, and wherein modify an operating characteristic of the sensor comprises: set a first signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a first value, set a second signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a second value, the second signal strength being different from the first signal strength, receive , from the calibrated sensor, measurement data of a time of flight of the signal emitted by the calibrated sensor and reflected from a surface inside the CTU, and determine a condition of the CTU based on the measurement data, wherein the condition of the CTU comprises an amount of loading of the CTU. a sensor ; a communication interface to communicate over a network ; and at least one processor configured to: receive a calibration parameter through the communication interface in order to calibrate the sensor, the calibration parameter transmitted by a remote service over the network, modify an operating characteristic of the sensor based on the calibration parameter, wherein the operating characteristic is a signal strength of a signal emitted by the sensor, and wherein modify an operating characteristic of the sensor comprises: set a first signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a first value, set a second signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a second value, the second signal strength being different from the first signal strength, receive , from the calibrated sensor, measurement data of a time of flight of the signal emitted by the calibrated sensor and reflected from a surface inside the CTU, and determine a condition of the CTU based on the measurement data, wherein the condition of the CTU comprises an amount of loading of the CTU. receive a calibration parameter through the communication interface in order to calibrate the sensor, the calibration parameter transmitted by a remote service over the network, modify an operating characteristic of the sensor based on the calibration parameter, wherein the operating characteristic is a signal strength of a signal emitted by the sensor, and wherein modify an operating characteristic of the sensor comprises: set a first signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a first value, set a second signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a second value, the second signal strength being different from the first signal strength, set a first signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a first value, set a second signal strength of the signal emitted by the calibrated sensor when the calibration parameter is set to a second value, the second signal strength being different from the first signal strength, receive , from the calibrated sensor, measurement data of a time of flight of the signal emitted by the calibrated sensor and reflected from a surface inside the CTU, and determine a condition of the CTU based on the measurement data, wherein the condition of the CTU comprises an amount of loading of the CTU. <EOS>