High-Quality GNSS Simulated Signal

SDX is designed from the ground up to provide precise and accurate GNSS signals in real time for the most demanding use cases. Experience the best in terms of precision, resolution, and ultra-high dynamic motion.

Figure 1. SDX Position error in 2D. Figure 2. SDX Position error in 3D.

Figure 1 and 2 show precision test results with Skydel's SDX simulator and high-grade GNSS receiver. Study published in Inside GNSS, July 2015 issue. Learn more about the study.

At the heart of SDX is an extremely optimized software algorithm with a 1000 Hz simulation iteration rate capable of modulating full band signals of all satellites for multiple constellations and frequencies.

Simulation Capabilities

Supported GNSS Constellations

  • GPS L1 C/A, L1P, L2P, L2C (open service), L5
  • GPS encrypted codes: Y, M (option available with Talen-X BroadSim)
  • GLONASS G1 & G2 (open service)
  • Galileo E1 & E5 (open service)
  • BeiDou B1 & B2
  • SBAS

Support for User-Defined Constellations and Signals

  • Agnostic simulation of customer-defined code and navigation messages
  • Support generation of evil waveforms
  • Arbitrary position/orbit for signal source/satellites
  • Arbitrary frequency band from 10MHz to 6GHz

Interference Simulation

  • Generation on the same RF output as GNSS signal (< 60 dB J/S ratio)
  • Generation on different RF output (< 150 dB J/S ratio)
  • In-band jammers
  • Out-of-band jammers

Signal Propagation and Errors Simulation

  • Multiple ionospheric models
  • Multiple tropospheric models
  • Transmitter/receiver 3D antenna pattern models
  • Relativistic effects
  • Multipath
  • Additive pseudorange ramps
  • Satellite clock error modification
  • Navigation message modification/corruption

Receiver Trajectory Simulation

  • Static
  • Circles
  • Car trajectory with integrated road map
  • Importation of arbitrary tracks/routes from NMEA, CSV or KML files
  • LEO / GEO orbits
  • 6 degrees of freedom (6DoF)
  • Hardware In the Loop (HIL)

Remote API

  • Open-source client library
  • Support for Python, C++ & C#
  • Python script exportation – user interactions with the simulator are automatically logged and can be exported as a python script


  • Real-time parsing and analysis of receiver’s NMEA data
  • Deviation graph and map updates in real time with simulated and receiver positions
  • Simulated data logging (receiver position, pseudorange, ionospheric delay, tropospheric delay, clock correction, etc.)
  • NMEA logging

Signal Specifications

Frequency Bands*

  • All GNSS bands
  • More than 2 RF outputs possible by combining multiple Software-Defined Radios
  • Baseband complex (zero IF) trough IQ samples logging

Signal Dynamics

  • Maximal relative velocity: 1,500,000 m/s
  • Maximal relative acceleration: no limits
  • Maximal relative jerk: no limits
  • 1000 Hz simulation iteration rate

Signal Accuracy

Pseudorange < 1mm
Pseudorange rate < 1mm/s
Inter-channel bias 0

Signal Quality*

Harmonics and Spurious < -40dBc
Phase noise < 0.005 rad RMS
Frequency stability < ±25x10-9 (with internal GPSDO unlocked)

RF Signal Level*

Max RF signal output -10 dBm (with no external attenuators)
Min RF signal output -170 dBm

RF Signal Level Control*

Range (per satellite) relative to reference level (-40 to +10) dB
Resolution 0.1dB
Additional range (variable amplifier) (0 to +30) dB

Synchronization Interfaces*

  • SMA 10 MHz IN
  • SMA 1 PPS IN (used as trig pulse)
  • SMA 10 MHz OUT

* Using Ettus USRP X300 and UBX RF daughterboards

Supported Operating Systems

  • Windows 8.1 and 10
  • Linux