GLONASS Receiver Inter-frequency Biases – Calibration Methods and Feasibility

J. B. Neumann, M. Bates, R. S. Harvey

Abstract:	The GLONASS satellite navigation system uses frequency-division-multiplexing to differentiate between the signals coming from the various satellites. High accuracy positioning using the GLONASS system can be affected by receiver biases between the different frequencies on both the pseudorange and carrier phase measurements. Biases can be caused by antennas, cables, SAW filters, and various components in the receiver’s front end. One method of reducing the effects of the biases is to calibrate them and remove them from the pseudorange (or carrier phase) measurements. The most straightforward ways of calibrating the biases involve calibrating pairs of receivers, or calibrating a single receiver to a multi-channel GLONASS simulator. These methods involve defining a “truth” calibration based on another piece of equipment, which is not generally desirable. The goal of the work described in this paper was to find a simple method of calibrating individual receivers, and if possible to find a method which could be done in the field, without the use of special calibration equipment, and to evaluate its effectiveness in reducing inter-frequency bias effects. Since SAW filters have been identified as a large source of inter-frequency biases in GLONASS receivers, a method was developed to calibrate the GLONASS inter-frequency pseudorange biases in the NovAtel GPS/GLONASS receiver caused by the SAW filter and other components following it in the signal path. The method uses a single GLONASS receiver with either live GLONASS and GPS satellite signals, or a single channel GLONASS simulator. The method is described in this paper along with results indicating the reduction in pseudorange bias achieved. Data is shown indicating the change in pseudorange and carrier phase bias over temperature. This temperature sensitivity can dictate the practicality of using calibration in some environments.
Published in:	Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999) September 14 - 17, 1999 Nashville, TN
Pages:	329 - 338
Cite this article:	Neumann, J. B., Bates, M., Harvey, R. S., "GLONASS Receiver Inter-frequency Biases – Calibration Methods and Feasibility," Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), Nashville, TN, September 1999, pp. 329-338.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In