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MARINE ELECTRONICS YEARB liliiBM^ U.S. Coast Guard DGPS Navigation Service (Continued from, page 38) radiobeacon providing correction GPS receiver capable of applying termine if the correction broadcast data link to DGPS service users. differential corrections. The cor- was tolerance. Integrity Monitor. Precisely lo- rected GPS position would be com- * Control btation bite for hu- cated MSK radiobeacon receiver and pared to the known position to de- man, centralized control of DGPb Ritchie sets a new standard in Electronic CompassTechnology... \ 1 1 270 w L /, 300', dV Vfe H mTCHIE / ^ - 06 1,1, > >v IAVi-I # «tn;.:» GPS/LORAN/SATNAV RADAR/CHART PLOTTER AUTOPILOT Easy Interfacing. Circle 219 on Reader Service Card 55 service element. Also, DGPS ser- vice performance data archiving and processing is accomplished here. • Communication Network. Pro- vides connectivity between sites for passing performance data and con- trol commands. DGPS user equip- ment consists of two interfaced re- ceivers with a display — a radiobeacon receiver capable of MSK demodulation, and a GPS receiver capable of applying differential cor- rections from the radiobeacon re- ceiver. Status Report At the time of this writing, 10 prototype reference stations com- prised the USCG DGPS service ar- chitecture. These 10 sites are trans- mitting GPS satellite corrections while being monitored by the USCG for evaluation purposes. The data collected is being used to analyze broadcast signal characteristics to ensure station availability, accuracy and reliability requirements are met. Exact numbers showing percentages for each requirement are not avail- able, as all sites are undergoing maintenance, upgrade and hard- ware installation. However, each site has performed quite well during on-air periods. The RTCM commit- tee has updated the broadcast for- mat standard and we are now using version 2.1. Version 2.2 is in progress. The RTCM committee also provided the Reference Station In- tegrity Monitor (RSIM) standard for the communication interface be- tween the Reference Station, Integ- rity Monitor, and Control Station. • Integrity Monitor. The soft- ware needed to provide system in- tegrity by monitoring RTCM correc- tion broadcasts and communicating that information back to the Control Station has been written by the USCG R&D Center. Testing and evaluation began with the installa- tion of the monitor equipment at the USCG Electronics Engineering Cen- ter (EECEN) in Wildwood, N.J. in June 1994. Integrity monitor hard- ware was installed at the Northeast test sites last September, and alarm messages were relayed to the con- trol station in Alexandria, Va. • Control Stations. The first ver- sion of the Control Station software was installed in the Eastern U.S. Control Station. The Control Sta- tion is undergoing testing and per- forming well while connected to the integrity monitor equipment at the N.E. test sites. • Communication Network. The USCG is using the federal govern- ment FTS2000 AT&T X.25 Packet Switched Service as the data link between the Control Stations and each DGPS site. This service is in place and meets all data communi- cation requirements. The building used to house the Maritime Reporter/Engineering News Remember, at Ritchie, Technology is never outdated...it's Standard. PU^ | ^^ | E. S. Ritchie & Sons, Inc. 243 Oak Street, Pembroke, MA 02359 Tel: (617) 826-5131 • Fax: (617) 826-7336 Ritchie's MagTronic Heading System is setting a new standard for Electronic Compass Technology. That's because the MagTronic Sensor produces a crisp, clean signal that converts directly to digital information with accuracy and repeatability un- matched by other sensors. This sensor can also provide identical heading data for all your on-board navigation instruments. In fact, you can usually connect up to three instruments including your compass display directly to the sensor. That's Easy Interfacing. If your electronics require several different signals all at one time, That's Easy too. All it takes is a MagTronic Interface Enclo- sure and simple slip-in MagTronic Interface Modules. Imagine, no more conflicting heading data. Your LORAN, GPS, SATNAV, CHART/PLOTTER, RADAR and AUTOPILOT will all have the same precise heading data and MagTronic's unmatched 1/2-of-onedegree accuracy. For more information about Ritchie Electronic Compasses, see your favorite Marine or Electronics Dealer or ask for your FREE Ritchie Catalog.. .it has everything you need to know about the new standard in modern Electronic Compass Technology...and Ritchie Magnetic Compasses, too.
