Frame transformation and geoid undulation transfer to GNSS real time positions through the new RTCM 3.1 transformation messages

Radio Technical Commission for Marine Services (RTCM) standardised messages play an important role in real time Global Navigation Satellite Systems (GNSS) applications such as navigation, positioning, civil engineering, surveying, and cartographic or cadastral production. One of the latest agreements on RTCM definitions contains the data fields for real time geodetic reference frame transformation and orthometric heights computation by received geoid undulations via internet protocol. These parameters can be generated dynamically by a GNSS data centre in a network of reference stations, encapsulated in RTCM messages and broadcasted to the rover location so they are centrally administered and the same frame transformations and geoid model are available to every user in the field, obtaining results in a local reference frame in real time. This paper summarises the functionality of the new RTCM 3?1 transformation messages, describes limitations and provides ideas about the possible use for solving specific problems. Test field campaigns are used to describe the real performance and usefulness of these new RTCM 3?1 messages