Pressure is one of the constitutional quantities governing the flow field in gas lubricated bearings. Knowledge of the pressure is of principal importance in the fundamental understanding of such bearings and for the calibration of reduced order models. These measurements can be done from the bearing side using pressure taps, yet, several details will not be captured. In order to acquire a continuous scan of the pressure field inside the bearing, it is necessary to measure from the rotor side. This paper presents an instrumented measurement rotor with embedded pressure probes and a wireless telemetry, which is capable of the continuous pressure field measurement inside a high-speed externally pressurized gas journal bearing. The bearing under investigation has a diameter of 40mm, L/D = 1, and was tested up to 37.5 krpm. Measurements at discrete points using pressure taps inside the test bearing were also performed for comparison. The measurements from both sides (bearing and rotor) were in good agreement at quasi-static conditions. At higher operational speeds, it was necessary to perform an in-situ system identification and calibration for the embedded pressure probes using the bearing side measurements as a reference. The in-situ system identification technique was successful to reconstruct the attenuated pressure signals for a wide range of supply pressures and rotor speeds. The instrumented rotor was proven qualified to perform time-resolved pressure measurements within the gas film of journal bearings up to 37.5 krpm.