Compared to their single frequency counterparts, dual frequency receivers are intrinsically immune to ionospheric error and converge faster in RTK (Real Time Kinematic). Although dual frequency software receivers were reported almost a decade ago [Ledvina, B. M., Psiaki, M. L., Sheinfeld, D. J., Cerruti, A. P., Powell, S. P., Kintner, P. M., "A Real-Time GPS Civilian L1/L2 Software Receiver," Proceedings of the 17th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2004), Long Beach, CA, September 2004, pp. 986-1005], there is no opensource in the public domain. This paper presents the design, implementation and test results of an open-source real-time L1/L2 software defined receiver (SDR). This work is an extension to gps-sdr, which is an open-source GPS L1 C/A real-time receiver. It accepts input IF (Intermediate Frequency) samples from either USRP1 (Universal Software Radio Peripheral) mother board with one DBSRX daughter board from Ettus Co., Ltd or GN3SV2 dongle from University of Colorado. Firstly, we use clock-tamer, an open-source GPSdisciplined clock to remove the instability of the on-board TCXO (Temperature Compensated Crystal Oscillator) of USRP1. TCXO of USRP daughter board is reported quite unstable [Di, Ruihui, Morton, Yu, Vinande, Eric, "Performance Analysis of a USRP Based GPS and GLONASS Signal Recording and Playback System," Proceedings of the 2013 International Technical Meeting of The Institute of Navigation, San Diego, California, January 2013, pp. 136-145.]. For example, the TXCO on board RFX series is 2.5 ppm (parts per million) rated, equivalent to nearly 4 kHz frequency deviation. Clock-tamer outputs a clock signal with stability of 0.28 ppm (without GPS) and 50 ppb (parts per billion) (with GPS) [http://code.google.com/p/clock-tamer. Retrieved at Sep 7, 2014.]. For demonstration purposes (i.e. not used in applications such as ionosphere scintillation monitoring), the frequency error that remains using Clock-tamer is tolerable. Secondly, we coded and tested its ability to output carrier phase. Thirdly, with the official announcement of L2 CNAV broadcasting on April 28th, 2014 [http://gpsworld.com/activation-of-pre-operationalcnav-message-set-for-april-28/ GPS World, retrieved on April 24th, 2014.], civil users have a new signal at a different frequency from L1. New code to process L2 CNAV were also developed and tested in this regard. Finally, we coded the processing algorithms for data coming from dual channels.


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    Titel :

    An Open-Source Real-Time L1/L2 Dual Frequency Software Receiver with an Open Source GPS-Disciplined Clock - Design, Implementation and Test


    Beteiligte:
    Zhang, Xin (Autor:in) / Zhang, Xingqun (Autor:in) / Feng, Shaojun (Autor:in) / Ochieng, Washington Y. (Autor:in)


    Erscheinungsdatum :

    2014


    Format / Umfang :

    7 Seiten, Bilder, Tabellen, 20 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Datenträger


    Sprache :

    Englisch




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