Remote integrity monitoring of DGPS by use of AIS infrastructure Tom Braute Norwegian Coast Directorate Presentation of a cost effective system for remote integrity monitoring of the Norwegian Coastal Administration DGPS service. The system use the infrastructure established for the Norwegian AIS network.

Overview Today: From 2007: Rationale for RIM system Local Integrity Monitoring (LIM) Weakness of LIM From 2007: Local and Remote Integrity Monitoring (LIM + RIM) Rationale for RIM system Description of RIM system Status and implementation plans

Norwegian Coastal Administration DGPS service DGPS radiobeacon Norwegian Coastal Administration DGPS service The Norwegian National Coastal Administration DGPS service is broadcasting differential GPS corrections from 12 maritime radiobeacons along the Norwegian coast. The DGPS service offers the mariner a position accuracy of 10 meters or better (1-3 meters in practice). The service also gives alarms on GPS failures (integrity alarms). The costs for establishing and operating the DGPS service is granted by the Ministry of Fisheries and Coastal Affairs.

Local integrity monitoring A Norwegian National Coastal Administration DGPS station comprises 2 reference stations 1 local integrity monitor 1 MSK modulator 1 Front-end PC Central Monitor periodically downloads alarms and statistics from each DGPS station tool for verifying operational status

Weakness of LIM system Logging of statistics Verification of service Monitor data for several hours occasionally lost No monitor data → unusable period Verification of service No information if contact to DGPS station is lost Must contact users directly

Rationale for RIM system Additional source to LIM for information on Current operational status Statistics → improved documentation on signal availability Improving today’s LIM might be wasted Will the future DGNSS include LIM at TX sites? RIM system can easily be adapted to future DGNSS Use of AIS infrastructure  cost effective implementation Independent to LIM infrastructure Each RIM site can monitor 2 DGPS stations RIM software based on AIS DGNSS software

Tasks for DGPS RIM The primary tasks for the remote integrity monitor (RIM) are: Perform integrity measurement of the DGPS data broadcast from DGPS stations Generate alarms when integrity measurements exceeds certain alarm thresholds Generate performance statistics for the DGPS stations which are monitored

Norwegian Coastal Administration AIS network DGPS radiobeacon AIS shore station Norwegian Coastal Administration AIS network AIS shore station with DGPS RIM RIM locations The Norwegian AIS network comprises 35 AIS shore stations operational service from early this year The AIS network provides an infrastructure is which is ideal for remote monitoring of the DGPS service.

Description of RIM system Configuration DGPS RIM at 8 AIS shore stations DGPS RIM communicates with DGPS central monitor by use of AIS IP-network Modified AIS Base Station Controller (BSC) GPS and DGPS receiver RIM software

AIS shore station with RIM The RIM functionality will be an integrated part of the Base Station Controller (BSC) of which there is one unit per AIS shore station

Status and plans for RIM system 8 AIS shore station sites with modified BSC HW Prototype RIM software for BSC developed and tested (demo project with Kongsberg Seatex AS) Further work (2006) Operational RIM software for BSC Upgrade DGPS central monitor system to utilize RIM alarm/status Configure IP-network to safely share bandwidth between AIS and RIM system

Thank you for your attention !!