GPS Solutions

, 23:8 | Cite as

Flex power on GPS Block IIR-M and IIF

  • Peter SteigenbergerEmail author
  • Steffen Thölert
  • Oliver Montenbruck
Original Article


GPS Block IIR-M and Block IIF satellites have the capability to redistribute transmit power between individual signal components. This so-called flex power can be used for increased protection against jamming and was already demonstrated in September 2010. Since January 2017, a geographically driven flex power mode has been enabled on ten Block IIF satellites. It is visible in carrier-to-noise density ratio observations of ground-based GPS receivers as well as differential code bias estimates between the L1 C/A- and P(Y)-code signals. Measurements with a 30 m high-gain antenna revealed a 2.5 dB increase of the L1 C/A and P(Y) power when the L1 M-code is regularly disabled. During four days in April 2018, a different flex power mode was put in place for all healthy Block IIR-M and IIF satellites. Carrier-to-noise density observations of geodetic GPS receivers show an increase of about 11 dB for combined L1 + L2 P(Y)-code power. The high-gain antenna measurements consistently show an increase of P(Y)-code power by 5 and 6 dB for L1 and L2, respectively, due to deactivation of the military M-code on both frequencies. Finally, during three days in April/May 2018, another type of flex power was observed: for 11 h of each of the three days, another geographically driven flex power mode was enabled but over a different area than the flex power mode mentioned above. Next to measurements of signal spectra, in-phase/quadrature components, and signal power with a high-gain antenna, the impact of flex power on the tracking and measurements of geodetic receivers is investigated.


Global Positioning System Transmit power Carrier-to-noise density ratio Differential code biases 



We’d like to acknowledge the efforts of the IGS/MGEX station operators and data centers.


  1. Barker BC, Betz JW, Clark JE, Correia JT, Gillis JT, Lazar S, Rehborn KA, Straton JR (2000) Overview of the GPS M code signal. In: Proc. ION NTM 2000, Institute of Navigation, Anaheim, California, USA, January 26–28, pp 542–549Google Scholar
  2. Betz J (2016) Engineering satellite-based navigation and timing—global navigation satellite systems, signals, and receivers. Wiley, Hoboken. CrossRefGoogle Scholar
  3. Defense Science Board (2005) The future of the Global Positioning System. Tech. rep., Office of the Under Secretary of Defense for Acquisition, Technology, and Logistics. Accessed 10 Aug 2018
  4. Dow JM, Neilan RE, Rizos C (2009) The international GNSS service in a changing landscape of global navigation satellite systems. J Geod 83(3–4):191–198. CrossRefGoogle Scholar
  5. Edgar C, Goldstein DB, Bentley P (2002) Current constellation GPS satellite ground received signal power measurements. In: Proc. ION NTM 2002, Institute of Navigation, San Diego, California, USA, January 28–30, pp 948–954Google Scholar
  6. Falletti E, Pini M, Presti LL (2011) Low complexity carrier-to-noise ratio estimators for GNSS digital receivers. IEEE Trans Aerosp Electron Syst 47(1):420–437. CrossRefGoogle Scholar
  7. Fisher SC, Ghasemi K (1999) GPS IIF—the next generation. Proc IEEE 87(1):24–47. CrossRefGoogle Scholar
  8. Hatch R (1982) The synergism of GPS code and carrier measurements. In: Proceedings of the third international symposium on satellite doppler positioning at physical sciences laboratory of New Mexico State University, Feb. 8–12, vol 2, pp 1213–1231Google Scholar
  9. Hauschild A, Montenbruck O (2016) A study on the dependency of GNSS pseudorange biases on correlator spacing. GPS Solut 20(2):159–171. CrossRefGoogle Scholar
  10. Håkansson M, Jensen ABO, Horemuz M, Hedling G (2016) Review of code and phase biases in multi-GNSS positioning. GPS Solut 21(3):849–860. CrossRefGoogle Scholar
  11. IS-GPS-200J (2018) Interface specification IS-GPS-200: Navstar GPS space segment/navigation user segment interfaces. Accessed 10 Aug 2018
  12. IS-GPS-705E (2018) Navstar GPS space segment/user segment L5 interfaces. Tech. rep., Global Positioning System Directorate Systems Engineering & Integration. Accessed 10 Aug 2018
  13. InsideGNSS Team (2010) IS-GPS-200E: flexing power and fixing phrase ambiguities. InsideGNSS. Accessed 10 Aug 2018
  14. International GNSS Service (IGS) RINEX Working Group and Radio Technical Commission for Maritime Services Special Committee 104 (RTCM-SC104) (2015) RINEX, the receiver independent exchange format, Version 3.03. Accessed 10 Aug 2018
  15. Jimenez-Banos D, Perello-Gisbert J, Crisci M (2011) The measured effects of GPS Flex power capability collected on sensor station data. In: 2010 5th ESA workshop on satellite navigation technologies and European workshop on GNSS signals and signal processing (NAVITEC).
  16. Laurichesse D, Mercier F, Berthias JP, Broca P, Cerri L (2009) Integer ambiguity resolution on undifferenced GPS phase measurements and its application to PPP and satellite precise orbit determination. J Inst Navig 56(2):135–149. CrossRefGoogle Scholar
  17. Melbourne WG (1985) The case for ranging in GPS based geodetic systems. In: Proceedings of the first international symposium on precise positioning with the global positioning system, edited by C. Goad, US Department of Commerce, Rockville, Maryland, USA, pp 373–386Google Scholar
  18. Montenbruck O, Steigenberger P, Prange L, Deng Z, Zhao Q, Perosanz F, Romero I, Noll C, Stürze A, Weber G, Schmid R, MacLeod K, Schaer S (2017) The multi-GNSS experiment (MGEX) of the International GNSS Service (IGS)—achievements, prospects and challenges. Adv Space Res 59(7):1671–1697. CrossRefGoogle Scholar
  19. Montenbruck O, Hauschild A, Steigenberger P (2014) Differential code bias estimation using multi-GNSS observations and global ionosphere maps. In: Proc. ION ITM 2014, Institute of Navigation, San Diego, California, USA, January 27–29, pp 802–812Google Scholar
  20. Partridge MD, Dafesh PA (2001) Code power measurement methodology for GPS Block IIR-M and IIF on-orbit test procedures. In: Proc. ION GPS 2001, Institute of Navigation, Salt Lake City, Utah, USA, September 11–14, pp 2764–2772Google Scholar
  21. Rajan JA, Irvine J (2005) GPS IIR-M and IIF: payload modernization. In: Proc. ION NTM 2005, San Diego, California, USA, January 24–26, pp 508–514Google Scholar
  22. Rajan JA, Tracy JA (2002) GPS IIR-M: modernizing the signal-in-space. In: Proc. ION GPS 2002, Institute of Navigation, Portland, Oregon, USA, September 24–27, pp 1585–1594Google Scholar
  23. Seybold JS (2005) Introduction to HF propagation. Wiley, HobokenCrossRefGoogle Scholar
  24. Steigenberger P, Hauschild A, Langley R (2017) US air force puts more power into GPS Block IIR-M C/A-code. GPS World 28(4):8–9Google Scholar
  25. Steigenberger P, Thoelert S, Montenbruck O (2018) GNSS satellite transmit power and its impact on orbit determination. J Geod 92(6):609–624. CrossRefGoogle Scholar
  26. Szilágyi B, Bar-Sever Y, Bertiger W, Romans L (2017) New methodology and operational service for near-real-time calibration of GNSS inter-signal biases. ION GNSS+ 2017, Institute of Navigation, Portland, Oregon, USA, September 25–29Google Scholar
  27. Thoelert S, Hauschild A, Steigenberger P, Langley R, Antreich F (2018) GPS IIR-M L1 transmit power redistribution: analysis of GNSS receiver and high-gain antenna data. J Inst Navig. CrossRefGoogle Scholar
  28. Thoelert S, Meurer M, Erker S (2012a) In-orbit analysis of antenna pattern anomalies of GNSS satellites. J Inst Navig 59(2):135–144. CrossRefGoogle Scholar
  29. Thoelert S, Meurer M, Erker S, Montenbruck O, Hauschild A, Fenton P (2012b) A multi-technique approach for characterizing the SVN49 signal anomaly, part 2: chip shape analysis. GPS Solut 16(1):29–39. CrossRefGoogle Scholar
  30. Thoelert S, Montenbruck O, Meurer M (2014) IRNSS-1A: signal and clock characterization of the Indian regional navigation system. GPS Solut 18(1):147–152. CrossRefGoogle Scholar
  31. Thoelert S, Furthner J, Meurer M (2013) GNSS survey—signal quality assessment of the latest GNSS satellites. In: Proc. ION ITM 2013, Institute of Navigation, San Diego, California, USA, January 28–30, pp 608–615Google Scholar
  32. Thoelert S, Erker S, Meurer M (2009) GNSS signal verification with a high-gain antenna—calibration strategies and high quality signal assessment. In: Proc. ION ITM 2009, Institute of Navigation, Anaheim, California, USA, January 26–28, pp 289–300Google Scholar
  33. Woo K (2000) Optimum semicodeless carrier-phase tracking of L2. J Inst Navig 47(2):82–99. CrossRefGoogle Scholar
  34. Wu A (2002) Predictions and field measurements of the GPS Block IIR L1 and L2 ground powers. In: Proc. ION NTM 2002, Institute of Navigation, San Diego, California, USA, January 28–30, pp 931–938Google Scholar
  35. Wübbena G (1985) Software developments for geodetic positioning with GPS using TI4100 code and carrier measurements. In: Proceedings of the first international symposium on precise positioning with the global positioning system, edited by C. Goad, US Department of Commerce, Rockville, Maryland, USA, pp 403–412Google Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.German Space Operations Center (GSOC)Deutsches Zentrum für Luft-und Raumfahrt (DLR)WeßlingGermany
  2. 2.Institute of Communications and Navigation (IKN)Deutsches Zentrum für Luft-und Raumfahrt (DLR)WeßlingGermany

Personalised recommendations