A Real-Time GPS/SBAS Time-Divided-Multi-Signal Quality Monitoring Receiver

N. Fujii, S. Saitoh, T. Hashimoto, M. Kawai, H. Nakao

Abstract:	GPS is widely used in many applications now. Safety-critical applications such as aircraft navigation require position information not only with high accuracy but also high integrity. To meet these two difficult requirements, Signal Quality Monitoring (SQM) is necessary for both the GBAS and the Space Based Augmentation System (SBAS). SQM must detect the distortion of the correlation-curve caused by satellite anomalies, such as "evil waveform". Electric Navigation Research Institute in Japan (ENRI) and Furuno Electric Co., Ltd.(FURUNO) have jointly developed a new GPS/SBAS receiver with real-time correlation-curve monitoring capability. This is the first prototype of the GPS/SBAS receiver with SQM in Japan. The receiver has 16 channels including 3 SBAS dedicated channels for L1 C/A signal tracking and 2 SQM channels. Each SQM channel has 127 correlation points distributed evenly at 0.025575 chip step. The width of the correlation monitoring range is about 3.2 chips. It can be allocated at any part of 1023-chip width by user selection. Each correlation point outputs both In-phase and Quadrature at 5 Hz. This receiver also supports Time-Divided-Multi-Signal Monitoring (TDMSM) mode, which changes monitoring satellite and/or monitoring range by time-sharing method. Using TDMSM, the receiver can produce up to 10 different satellites´ correlation-curves at 1 Hz update rate. That means most of the time, the receiver monitors all visible satellites in real-time. In addition to the SQM capability, the receiver can output up to 5 different position-fixes, such as GPS, DGPS, SBAS#1, SBAS#2, and SBAS#3. Raw observation data, such as accumulated carrier phase, pseudorange, carrier-to-noise ratio, Doppler-shift, and time-tag are also outputted at 5 Hz. The receiver is equipped with Ethernet. It allows us fast data output via network environment. We also developed data recorder program on the personal computer (PC). This paper introduces the detail specification of the SQM receiver and presents data collected in three different environments; (1) using parabolic antenna; (2) usual fixed-point observation; (3) multipath by GPS/SBAS simulator;
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	1829 - 1842
Cite this article:	Fujii, N., Saitoh, S., Hashimoto, T., Kawai, M., Nakao, H., "A Real-Time GPS/SBAS Time-Divided-Multi-Signal Quality Monitoring Receiver," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 1829-1842.
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