If thrust were to be measured by strain gauges the thrust measurements would be in the order of 35 micro strains which would lead to a far too large inaccuracy and therefore alternative methods are to be used.
High definition sensors are therefore developed and used in the thrust meter.
The thrust meter measures the RPM, torque and thrust on the shaft
The measuring accuracy is in the range of 0.1 % and the update period of measurements can be varied.
By measuring thrust and torque it is possible to indicate the propeller efficiency.