The transmission of satellite signals at two widely spaced frequencies allows correction of the ionospheric delay. Both GPS and GLONASS transmit such signals, and to date there have been no published dual frequency GLONASS studies. This paper shows the fundamental accuracy of the Leeds University multichannel GPS/GLONASS receiver. Details are then given of the processing methods that have been used to obtain the ionospheric group delay using GLONASS L1 and L2 P‐code measurements. Examples of the measured delay are provided and compared with the GPS model. Navigation results are shown using the P‐code phase at L1 only and with a combination of the L1 and L2 measurements. An analysis of the accuracy of the P‐code pseudorange and navigation capability is presented.

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Dynamic, mobile platforms offer the opportunity to analyze robustness to satellite outages due to aircraft maneuvers or other real-world situations where interruptions in continuity, in particular, can potentially be problematic. And real-time implementation serves to demonstrate the state of readiness of the algorithm to meet its intended purpose-providing high-integrity navigation for aircraft. To this end, a flight test was arranged to test ARAIM operation in flight. For this paper, the ARAIM user algorithm was implemented using GPS and GLONASS in real-time in flight at the airport in Atlantic City, NJ. Several flight profiles were flown to inject typical aircraft dynamics into the system. The real-time data was analyzed to understand the effects of aircraft dynamics on receiver on the horizontal and vertical protection levels. It is shown that the ARAIM algorithm may be sensitive to aircraft dynamics and that adequate characterization of the multipath errors and proper mitigation of cycle slips may play a significant role in achieving expected continuity and availability.

Global navigation satellite systems comprising the Navstar GPS and GLONASS systems and to be supplemented by an Inmarsat-3 overlay, will soon be operational. Full Operational Capability (FOC) for GPS can be expected early in 1995. For GLONASS progress towards FOC will be slower with a final completion date probably nearer 1996-98. Particularly in view of the interest in joint GPSlGLONASS initiatives, the progress of both systems towards a full operational complement deserves constant attention.