LE34 Tele has acquired an unmanned helicopter and wants to use this for photogrammetric purposes. To optimize the workflow, a system using carrier phase observations is developed. This system calculates the exterior orientation to images captured from the helicopter. The developed system records timestamps from the hot shoe of the camera. These timestamps are afterwards used for interpolation of coordinates to the camera stations. This interpolation incorporates post-processed GPS positions. Due to the fact that the installed GPS-receiver, EVK-6T, uses Squaring in the internal Phase Lock Loop, the observations can be displaced by half a wavelength. Because of this, several different software solutions are applied to the collected GPS observations, with various results. Development of the system and associated processing routines are carried out and afterwards a flight with the system determines the overall accuracy. It is concluded that the system functions as planned, but the processing of GPS observations must be optimized. Alternatively, an improved GNSS receiver should be installed.