A software GNSS receiver is a Global Navigation Satellite System (GNSS) receiver that has been designed and implemented using software-defined radio stations.

A GNSS receiver, in general, is an electronic device that receives and digitally processes the signals from a navigation satellite constellation in order to provide position, velocity and time (of the receiver).

GNSS receivers have been traditionally implemented in hardware: a hardware GNSS receiver is conceived as a dedicated chip that has been designed and built (from the very beginning) with the only purpose of being a GNSS receiver.

In a software GNSS receiver, all digital processing is performed by a general purpose microprocessor. In this approach, a small amount of inexpensive hardware is still needed, known as the frontend, that digitizes the signal from the satellites. The microprocessor can then work on this raw digital stream to implement the GNSS functionality.

Hardware vs. software GNSS receivers

When comparing hardware vs software GNSS receivers, a number of pros and cons can be found for each approach:

  • Hardware GNSS receivers are in general more efficient from the point of view of both computational load and power consumption since they have been designed in a highly specialized way with the only purpose of implementing the GNSS processing.
  • Software GNSS receivers allow a huge flexibility: many features of the receiver can be modified just through software. This provides the receiver with adaptive capabilities, depending on the user's needs and working conditions. In addition, the receiver can be easily upgraded via software.
  • Under some assumptions, Software GNSS receivers can be more profitable for some applications, as long as sufficient computational power is available (and can be shared among multiple applications). For example, the microprocessor of a smartphone can be used to provide GNSS navigation with the only need of including a frontend (instead of a full, more expensive, hardware receiver).

Currently, most of the GNSS receiver market is still hardware. However, there already exist operational solutions based on the software approach able to run on low-cost microprocessors. Software GNSS receivers are expected to increase their market share or even take over in the near future, following the development of the computational capabilities of the microprocessors (Moore's law).

Comparison of GNSS SDR implementations

  • Galileo Satellite Navigation LTD.- GSN: Business Model - IP core license + royalties Development Programming language: C User interface - NMEA Hardware support: Platforms PC - windows PC - Linux CEVA - XC family CEVA - TL3/4 Cadence (Tensilica) - BBE16/32 RF FE MAXIM NEC GNSS/SBAS signals support: GPS: L1/CA, GLONASS: G1 Galileo: E1, BeiDou: B1 SBAS QZSS: L1/CA Features: Acquisition: yes Tracking: yes Generating pseudo-range observable: yes Decoding navigation data: yes Position estimation: yes Maximum number of real-time channels demonstrated: 16/system Multi-correlator: yes Sample data recording: yes
  • SX3 (formerly SX-NSR) General information: Publication: Development: Programming language: C++ User interface (none, CLI, GUI): CLI, GUI Under active development (as-of date): yes (2016-Mar-17) Creator/sponsor organization: IfEN GmbH, Germany Latest release (version and date): v3.2.1, March 2016 First release (version and date): v1.0, March 2007 Hardware support: Front-ends: NavPort, NavPort-4, SX3 frontend Host computer special hardware supported: SIMD (SSE2, SSSE3), CUDA Multicore supported: yes GNSS/SBAS signals support: GPS: L1CA, L2C, L2P (codeless), L5 GLONASS: G1, G2 Galileo: E1, E5a, E5b, E5ab (AltBOC), E6 BeiDou: B1, B2 SBAS: EGNOS QZSS: L110CAdieyure IRNSS: L5, S-Band Features: Acquisition: yes (several algorithms) Tracking: yes (several algorithms) Generating pseudo-range observable: yes Generating carrier-phase observable: yes Decoding navigation data: yes Spectrum analyzer: yes Position estimation: yes Maximum number of real-time channels demonstrated: 490 (GPS L1 C/A channels @20 MHz sample rate, 3 correlators per channel, INTEL Core i7-4970K processor (not over clocked) ) Application programming interface: yes Dual antenna support: yes Scintillation monitoring: yes Multi-correlator: yes Sample data recording: yes Multipath mitigation: yes (several algorithms)
  • GNSS-SDRLIB General information: Publication: Software licence: GNU General Public License 2+ Development: Programming language: C User interface (none, CLI, GUI): CLI, GUI. Number of developers: 1? Under active development (as-of date): yes (2013-Sep-25) Creator/sponsor organization: Tokyo University of Marine Science and Technology, Japan Latest release (version and date): First release (version and date): Hardware support: Front-ends: NSL STEREO v2 and SiGe GN3S Sampler v3 Host computer special hardware supported: SIMD (SSE2 and AVX) Multicore supported?: GNSS/SBAS signals support: GPS: L1CA, L1C, L2C, L5 GLONASS: G1, G2 Galileo: E1, E5a, E5b BeiDou: B1 QZSS: LEX Features: Acquisition: yes Tracking: yes Generating pseudo-range: yes Decoding navigation data: yes Spectrum analysis: yes Position estimation: yes (through RTKLIB) Maximum number of real-time channels demonstrated: ?
  • ARAMIS (formerly iPRx) Versions: Free academic version Ionospheric Scintillation Monitor receiver R&D version General information: Publication: Development: Programming language: C++ User interface : GUI Under active development (as-of date): yes (2014-Nov) Creator/sponsor organization: iP-Solutions, Japan, JAXA, Japan Latest release (version and date): February 2018 First release (version and date): April 2008 Hardware support: Front-ends: Eagle, FEM, Simceiver Multicore supported: yes GNSS/SBAS signals support: GPS: L1CA, L2C BeiDou B1, B2 GLONASS: G1, G2, G3 Galileo: E1 IRNSS: L5, S QZSS: L1CA SBAS Features: Acquisition: yes Tracking: yes Generating pseudo-range observable: yes Generating carrier-phase observable: yes Decoding navigation data: yes Position estimation: yes Maximum number of real-time channels : 60 (5 correlators per channel) Application programming interface: yes Dual antenna support: yes, for FEM front end Multi-correlator: yes Sample data recording: yes
  • SoftGNSS v3.0 (also known as SoftGPS) General information: Publication: Source code: included with the book Software licence: GPL v2 Non real-time (post-processing) GNSS software receiver Development: Programming language: MATLAB User interface (none, CLI, GUI): CLI and GUI Number of developers: 4 (along the project) Under active development (as-of date): public version - no, non-public versions - yes (2013-Sep-30) Hardware support: Front-ends: SiGe GN3S Sampler v1 (in the original SDR and driver release). Signal records originating from other Sampler versions or other front-ends require configuration changes and in some cases also minor code changes. Host computer special hardware supported: no Multicore supported?: no GNSS/SBAS signals support (separate version for each band of each GNSS): GPS: L1CA Features: Acquisition: yes Tracking: yes Generating pseudo-range observable: yes Generating carrier-phase observable: no Decoding navigation data: yes Position estimation: yes
  • GNSS-SDR, An open source GNSS Software Defined Receiver General information: Software licence: GPL v3 Development: Programming language: C++ User interface (none, CLI, GUI): CLI. Number of developers: 26 (along the project) Under active development (as-of date): yes (2021-Jan-08) Creator/sponsor organization: Centre Tecnològic de Telecomunicacions de Catalunya Latest release (version and date): 0.0.14 (as Jan 2021) First release (version and date): 2011-Mar-11 first svn commit Hardware support: Front-ends: UHD-compatible (USRP family), OsmoSDR-compatible (RTL2832-based USB dongles, bladeRF, HackRF One), SiGe GN3S Sampler v2, AD-FMCOMMS2-EBZ Host computer special hardware supported: SIMD (via VOLK and VOLK_GNSSSDR), CUDA Multicore supported?: Yes GNSS/SBAS signals support: GPS: L1CA, L2C, L5 GLONASS: L1SP, L2SP Galileo: E1b, E1c, E5a BeiDou: B1I, B3I SBAS: EGNOS Features: Acquisition: yes (several algorithms) Tracking: yes (several algorithms) Generating pseudo-range observable: yes Generating carrier-phase observable: yes Decoding navigation data: yes Position estimation: yes Maximum number of real-time channels demonstrated: > 100 Output formats: RINEX, KML, GPX, GeoJSON, NMEA, RTCM, intermediate results stored in binary .mat files readable from MATLAB and Octave, and from Python via h5py.
  • GRID, Generalized Radionavigation Interfusion Device General information: Software licence: Commercial Publication: Contact: , Development: Programming language: C++ Platforms: Linux, Windows, MacOS User interface (none, CLI, GUI): CLI. Number of developers: 15 (along the project) Under active development (as-of date): yes (2023-Apr-28) Creator/sponsor organization: University of Texas at Austin Latest release (version and date): 2022 annual release First release (version and date): 2008-Jul-01 Hardware support: Front-ends: Several and, practically speaking, any. Host computer special hardware supported: Intel SIMD (SSE2 through AVX-512), ARM NEON (64-bit and 128-bit) Multicore supported?: Yes GNSS/SBAS signals support: GPS: L1CA, L2C, L5 Galileo: E1b, E1c, E5a QZSS: L1CA SBAS: WAAS L1 Features: Acquisition: yes (several algorithms) Tracking: yes (several algorithms) Generating pseudo-range observable: yes Generating carrier-phase observable: yes Decoding navigation data: yes Position estimation: yes Multiple antennas: yes Real-time Kinematic: yes, GRID can function as an RTK-base station or rover with integrated network support, RTK estimation when integrated with PpEngine (available through separate license) Differential corrections: yes, CNAV and SBAS Maximum number of real-time channels: Hardware-dependent, 30 on a Raspberry Pi 1, >100 on most desktop computers. Output formats: RINEX, KML, MATLAB .mat files, CSV, proprietary GBX (GRID binary exchange) format. Current applications: experimental FOTON receiver, several GNSS-RO commercial applications, commercial LEO satellite on-board navigation, RTK-based rocket navigation (launch-to-orbit), RTK-based vehicle navigation in urban environments, RTK-based drone, several fixed reference stations, signal abnormality monitoring

Further reading

  • Borre, K; Akos, D; Bertelsen, N; Rinder, P; Jensen, S H (2007). A software-defined GPS and Galileo receiver: a single-frequency approach. Birkhauser. ISBN 978-0-8176-4390-4.
  • Pany, Thomas (2010). Navigation Signal Processing for GNSS Software Receivers. Artech House. ISBN 9781608070282.
  • Petrovski, Ivan; Tsujii, Toshiaki (2012). Digital satellite navigation and geophysics a practical guide with GNSS signal simulator and receiver laboratory. Cambridge University Press. ISBN 9780521760546.

External links