In addition to applications in aircraft navigation, pseudolites are used for positioning and navigation in open pit mines, harbors, or urban areas. Furthermore, the Galileo Test Environments (GATE) installed in Germany, namely the AIR, SEA, RAIL and AUTOMOTIVE GATE, are equipped with pseudolites to emulate Galileo signals and to test and develop new navigation algorithms, concepts, and hardware. However, observation from such pseudolite infrastructures are often suffering from signal diffraction, multipath or temporal blockage reducing significantly the positioning performance. To overcome these issues, a virtual receiver concept is proposed that combines pseudolite observations from multiple antennas optimally installed on a platform into one platform solution. Using measurements from a ferry in the SEA GATE environment, we show that depending on the trajectory segment (approach, harbor, docking), the availability of positioning and heading can be increased from ca. 60% to up to 80% if the virtual receiver concept is applied. Furthermore, the solution with the virtual receiver is more robust since the impact of undetected observation errors on the coordinates is significantly reduced and the RAIM (realized by a fault detection and exclusion scheme) availability increased. The precision of positioning in terms of coordinate standard deviation is improved by 10%. We analyze the pseudolite data quality and discuss variations in the carrier to noise density ratio. Challenges are signal interference between pseudolite signals and GNSS signals as well as signal diffraction and dynamic multipath due to the changing environment such as cranes, further ships or cargo and containers to be loaded. In order to fully exploit the potential of pseudolite networks, adequate correction models for tropospheric refraction as well as observation weighting are needed. In this contribution, we propose a new tropospheric correction model based on results from electro-optic distance measurements. Depending on pressure, temperature, and humidity typical corrections reach ～300 ppm, i.e. 30 cm per km.
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