framework, based on continuous observation and analysis of GNSS data in the Asia-Pacific region. ARP Antenna Reference Point – the physically accessible point on a GNSS antenna to which all measurements related to that antenna are referred. AuScope An Australian federal program funded by the National Collaborative Research Infrastructure Strategy (NCRIS). A component of this program is the installation of up to 100 GNSS CORS and other geodetic technology for an increased understanding of the Australian tectonic plate and improvement of the national geodetic reference frame. DOMES Directory of MERIT Sites – historically, the DOMES numbering system was designed at the start of the MERIT campaign in the early 1980s in order to give an unambiguous identifier to all instrument reference points and markers. Since 1988, a DOMES number has been issued for all stations contributing to the ITRF. Elevation mask A GNSS receiver setting that determines whether GNSS signals are recorded below a certain angle above the horizon. IGS International GNSS Service - An international federation of agencies that pool resources to operate a global CORS network whose data is used, amongst other purposes, to generate precise GNSS products in support of Earth science research. Multipath Errors in GNSS observations caused by reflected GNSS signals interfering with the direct GNSS signal because of their common time origin but different path lengths. NGS : A United States of America Federal agency that manages the national coordinate system and a GNSS antenna calibration service. NMS Network Management System – a combination of hardware and software that monitors the components of a computer network and informs an operator whenever an outage occurs. NTRIP RTCM-Special Committee 10410.x Standard for Networked Transport of RTCM via Internet Protocol is an application-level protocol for streaming GNSS data over the Internet. PDU Power Distribution Unit – a device that manages the distribution of power to network components. Regulation 13 The process of verification of a reference standard of a position-measurement in accordance with Regulation 13 of the National Measurement Regulations 1999 and the National
Where fixtures do not entirely penetrate a foundation wall, use ChemSetTM stainless steel bolts penetrating at least half the wall width. Ensure that sufficient safety provisions (harness points, ladder brackets etc.) are available for personnel installing or maintaining roof mounted monuments and equipment. Figure 6 shows examples of Tier 3 bracketed, post, and post and stay CORS antenna monuments (courtesy Department of Sustainability and Environment, Victoria, Department of Natural Resources and Mines, Queensland, and Land and Property Information New South Wales). CORS Additional information on CORS antenna monuments is available from the resources: IGS Monumentation Design and Implementation Web page, available from: NGS National Continuously Operating Reference Station Monumentation Process Action Final Report, available from: UNAVCO Knowledgebase – GNSS Station Monumentation Web page, available from: Figure : Sample Tier 3 CORS monuments Antenna mounts The antenna mount connects the GNSS antenna to the monument. Once installed the antenna mount should lock the antenna in place so it cannot move or rotate. When an antenna is removed and replaced, the mount should return the antenna reference point to the same location and orientation. The antenna mount must maintain a level antenna, oriented to within 5° of true north for antenna calibrations to be effective. Using thin shims or washers allow the antenna to be oriented to true north, but will introduce a height of antenna that must be carefully communicated to data consumers to allow accurate positioning. Figure 7, Figure 8 and Figure 9 show some example CORS mounts. A survey tribrach is not considered an acceptable antenna mount.
Cable Splitters Only use antenna splitters where a secondary receiver is connected or planned. DC block the splitter to the secondary receiver. Record splitters in the station site log and metadata. Lightning Protection Include a grounded lightning protector in the antenna cable, especially in lightning prone areas. In lightning prone areas, reduce the horizontal cable-run length to minimise the risk of signal induction from nearby lightning strikes. If this is not possible, fit the lightning arrestor toward the receiver end of the cable. Cable Type Use an antenna cable type sufficient for the length of the intended cable run between antenna and receiver. The selected cables and components should have a total signal loss of less than 9 dB over the length of the cable run. Meteorological and other sensors Meteorological data aids understanding the CORS ambient environment and assists GNSS processing and the development of improved weather models. Other sensors that may be included at CORS sites include cameras, sunlight sensors to monitor solar performance, and security equipment such as motion sensors. External dedicated meteorological sensors are required at Tier 1 and 2 CORS sites to provide a continuous meteorological record at the site. Install meteorological sensors separately from the CORS monument to minimise any increase in the multipath environment. RINEX may be used to record and transmit meteorological data. Survey the position of all auxiliary sensors for inclusion in the site logs and metadata. Meteorological sensors at CORS sites have the following requirements: pressure measurement accuracy better than ± 0.5 hPa; temperature measurement accuracy better than ± 1° C; relative Humidity measurements better than ± 2%; and The height difference between the pressure measurement reference mark of the meteorological sensor and the CORS reference point should be determined to better than 10 millimetres.