Assessing GLONASS Observation

Alfred Leick, Jacques Beser, Paul Rosenboom, Barbara Wiley

Abstract:	Processing of GLONASS observations differs in several aspects from that of GPS. The broadcast ephemeris is provided every 30 minutes and requires a numerical integration. Using the fourth order Runge Kutta method, sample integrations show that a 1-second integration interval provides about 3 m accuracy over 30 minutes. Because GLONASS presently does not contain selective availability (SA), the between-satellite differences and the navigation solutions reveal SA on GPS satellite transmissions. Thirty daily UREs (User Range Errors) fall within the 5- 11 m range, with one exception at about 14 m. A definitive value for the URE for GLONASS could, unfortunately, not be made because the antenna was not located at an accurately surveyed point. The single difference and double difference processing techniques are contrasted for baseline solutions. A single difference system bias (SDSB) for phases is introduced and determined from single and double difference solutions. The double difference solution shows a dependency on the accuracy of the initial coordinates. The single difference solution does not have such a dependency. For both types of solutions, the double difference ambiguities can be fixed using the LAMBDA technique. All computations were done with G 2 ™. The coordinates estimated by the single and double difference solutions agree within one millimeter even though the initial coordinates are off by 1.7 m. With GPS and GLONASS combined, the ambiguities can be fixed at all epochs, including the first one. Observations of GPS alone require at least ten 1-second epochs.
Published in:	Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998) September 15 - 18, 1998 Nashville, TN
Pages:	1605 - 1612
Cite this article:	Leick, Alfred, Beser, Jacques, Rosenboom, Paul, Wiley, Barbara, "Assessing GLONASS Observation," Proceedings of the 11th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1998), Nashville, TN, September 1998, pp. 1605-1612.
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