1. Reliability Characteristics of Differential GPS Transmission Cezary Specht Institute of Navigation and Maritime Hydrography Naval University in Gdynia CSpecht@amw.gdynia.pl

2. AccuracyAccuracy Fix rateFix rate CapacityCapacity AmbiguityAmbiguity Fix dimensionFix dimension CoverageCoverage AvailabilityAvailability ReliabilityReliability ContinuityContinuity IntegrityIntegrity year 2000year 1995 year 1990 International Association of Lighthouse, International Association of Lighthouse, European Radionavigation Plan, European Radionavigation Plan, Federal Radionavigation Plan. Federal Radionavigation Plan. The importance of the navigation systems comparable criteria during the last years ?

3. Differential GPS transmission methods

4. Availability of Differential GPS transmission The availability will be the state in which the age of at least 4 pseudorange corrections related to various satellites is lower than the maximum.

5. The process of PRCs transmission for N s ={7,8,9}

6. Availability of DGPS transmission the process of PRCs transmission for N s ={7,8,9} The binary state vectors of the system : and the functions of their structures

7. After decomposition: AVAILABILITY: Availability of DGPS transmission the process of PRCs transmission for N s ={7,8,9}

8. Transmission availability calculation (1) DGPS RS signal strength level Noise level SNR=f(BER)

9. Transmission availability zones zones Transmission availability calculation (2) SNR=f(BER) Transmission model

10. Reliability and Continuity of Differential GPS transmission any moment in time time period failure rate - renewal rate - Reliability function

11. some comparative analyses... The increase in the number of satellites, for which the reference station transmits pseudorange corrections by message RTCM type 9-3, improves the availability Type of the message, bit rate vs BER

12. 1.The aim of this presentation has been to develop a mathematical model of availability, reliability and continuity of differential GPS transmission based on probabilistic approach. 2.The problem was important because of the lack of methods, which would enable the parameter prognosis with regard to the process of navigation. In this light, the problem reliability characteristics constitutes one of the fundamental issues for multi-criteria assessment of modern systems at the stage of system testing and exploitation as well. 3.The theory the author worked out has been referred to the probabilistic characteristics of navigation systems functioning such as expected value, variance, or standard deviation. Conclusions Specht C., (2003) Availability, Reliability and Continuity of Differential GPS Transmission, Annual of Navigation, no 5/2003, Polish Academy of Sciences, Gdynia, 2003, 85 pages.