PPP-Serve - Network based GNSS Phase Biases to enhance PPP Applications A new Service Level of GNSS Reference Station Providers

The project PPPserve (Network based GNSS Phase Biases to enhance PPP Applications A new Service Level of GNSS Reference Station Provider) aims at the development and realization of adequate algorithms to enhance fast GNSS based point positioning at cm level. Regularly established RTK-techniques (Real-Time-Kinematic) are based on building and processing observation differences while the required observation corrections are forwarded to the user community in the standardized RTCM format. In contrast to the differencing technique the PPP-model is based on code/phase single point positioning, which requires a limited amount of correction data just transferring model parameters instead of observation corrections. Leading manufacturers have agreed on a new RTCM Standard (RTCM 3.2, State Space Representation = SSR) which supports PPP. New receiver hard- and software issued from 2012 onwards will be capable to process this standard. Therefore GNSS-service providers have to adapt to this situation by offering new service levels. Unfortunately global SSR information like satellite orbit- and clock-correction models do still not allow for phase ambiguity resolution in real-time and suffer from long convergence times (some minute compared to RTK). PPPserve aims in a further step at the provision of so-called satellite-phase-biases which are the missing link at user side to allow for PPP based phase ambiguity resolution. Applying relevant satellite phase-biases will reduce the convergence time down to a few seconds. Both currently known techniques for establishing these phase biases will be investigated. Software to determine these parameters from the observation data of the regional GNSS service provider (Wien-Energie-Stromnetz/EPOSA) will be established. Finally these parameters are forwarded to the user community in a proprietary format as a new service level. The project covers aside of GPS also the use of GLONASS satellite signals and the processing of relevant GLONASS phase biases. Investigations concerning Galileo-IOV signal depend on the availability of the IOV-signals during the project life span.