Welcome to the Global Navigation Multi-Constellation

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[6]	Expert opinions: challenges faced by multi-constellation GNSS receiver designers [Internet]. Santa Ana: GPS World; 2018 Feb 8 [cited 2021 Jan 31]. Available from: https://www.gpsworld.com/expert-opinions-challengesfaced-by-multi-constellation-gnss-receiver-designers/.

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[8]	Parkinson B. Assured PNT for our future: PTA [Internet]. Santa Ana: GPS World; 2014 Sep 1 [cited 2021 Feb 3]. Available from: http://digital.gpsworld.com/September2014#&pageSet=39.

[9]	International committee on global navigation satellite systems (ICG) [Internet]. Vienna: United Nations Office for Outer Space Affairs; [cited 2021 Feb 1]. Available from: https://www.unoosa.org/oosa/en/ourwork/icg/icg. html.

[10]	Wang W, Wang Y, Yu C, Xu F, Dou X. Spaceborne atomic clock performance review of BDS-3 MEO satellites. Measurement 2021. In press.

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[12]	Directorate-General for Defence Industry and Space. EU Space investments to the rescue [Internet]. Brussels: European Commission; 2020 Dec 2 [cited 2021 Feb 1]. Available from: https://ec.europa.eu/defence-industry-space/eu-spaceinvestments-rescue-2020-12-02_en.

[13]	Li G, Guo S, Lv J, Zhao K, He Z. Introduction to global short message communication service of BeiDou-3 navigation satellite system. Adv Space Res 2021;67:1701–8.

[14]	Parkinson BW, Powers ST. The origins of GPS: fighting to survive, part 2 [Internet]. Santa Ana: GPS World; 2020 Jun 1 [cited 2021 Feb 1]. Available from: https://www.gpsworld.com/origins-gps-part-2-fighting-survive/.

[15]

BeiDou completes inter-satellite link testing; only GNSS with this accuracyimproving feature [Internet]. Red Bank: Inside GNSS Media & Research; 2020 Jun 18 [cited 2021 Jan 31]. Available from: https://insidegnss.com/BeiDoucompletes-inter-satellite-link-testing-only-gnss-with-this-accuracy-improvingfeature/.

[16]	Development of the BeiDou navigation satellite system (version 4.0). Report. Beijing: China Satellite Navigation Office; 2019 Dec.

[17]	New civil signals [Internet]. Washington, DC: GPS; [cited 2021 Jan 31]. Available from: https://www.gps.gov/systems/gps/modernization/civilsignals/ #L1C.

[18]	Market understands value of dual frequency [Internet]. Prague: European Global Navigation Satellite System Agency (GSA); 2020 Jan 28 [cited 2021 Feb 1]. Available from: https://www.gsa.europa.eu/newsroom/news/marketunderstands-value-dual-frequency.