Multi-Constellation Precise Orbit Determination GNSS Receiver

The Product

GPS based Precise Orbit Determination uses high-quality carrier and code measurements of a multi-frequency GPS receiver on-board of a satellite to achieve a position measurement accuracy of this satellite of a few centimetres in an on-ground post-processing run.

Based on extensive GPS experience and flight heritage of RUAG Space GmbH (RSA) the multi-frequency GPS Precise Orbit Determination (POD) receiver provides high integration of the RF- and digital circuits as key innovations, thus resulting in low mass and low power.

The GPS POD Instrument down-converts and digitizes the GPS L1 and L2 signals by means of dedicated RF- and mixed-signal ASICs. The AGGA-2 chips and a LEON processor form the heart of the digital signal processing.

This product has been developed together with RUAG Space in Sweden consolidating the expertise and capabilities of both sites. 

Main features

  • Antenna with improved gain and multipath suppression performance
  • Selective RF-filter and low-noise amplifier for improved performance figures: these two features enable long tracking arcs especially important for POD processing
  • Advanced code-phase and carrier-phase processing
  • Accurate force model-based orbit propagator
  • Advanced Kalman filtering allows high on-board navigation performance
  • Flexible acquisition and tracking concept providing:
    ƒ- dual-frequency signal processing of up to 18 satellites or
    ƒ- single frequency signal processing of up to 24 satellites
    ƒ- Sliding search window for minimized acquisition times
    ƒ- Doppler-based loop aiding
    ƒ- Highly configurable due to numerous parameters like tracking loop filter
      order and bandwidth, integration time, discriminator type
  • Configurable data rate per measurement type
  • Autonomous start-mode determination for minimized time-to-first-fix
  • Powerful parameter interface supports changes in standby and operational mode
  • Additional data products provide excellent visibility of receiver internals
  • Monitoring of external ultra-stable oscillator (USO) long term drift possible
  • Low mass and power consumption

Data Products:

  • Navigation solution based on GPS/GALILEO constellations
  • Generation of the PPS signal synchronized to GPS/GALILEO second
  • Carrier phase measurements for each tracked signal
  • Code phase measurements for each tracked signal
  • Support data:
    - Tracking state
    - GDOP
    - Carrier to noise (C/N0) measurement of each tracked signal
    - Noise measurements of each RF down-conversion chain
    - Satellites in view status
    - Satellite navigation message 


  • TC/TM interface: UART (RS-422) or MIL-STD-1553B or SpaceWire
  • PPS output nom/red/test (RS-422)
  • Primary power interface 28 V unregulated
  • ON/OFF high level command interface or autostart upon voltage application
  • Thermistor TM interfaces
  • External USO input available

On-board Navigation Solution Accuracy:

  • Position: 1.0 m 3D rms
  • Velocity: 2 mm/s 3D rms
  • Time offset 1PPS (1σ) : < 50 ns (typ. 25ns rms)

Instrument data outputs:

  • L1 carrier phase error < 2 mm rms
  • L2 carrier phase error for P(Y) < 10 mm rms
  • L2 carrier phase error for L2C < 3 mm rms
  • L5 carrier phase error < 1.6 mm rms
  • E1 carrier phase error < 2.7 mm rms
  • E5a carrier phase error < 1.8 mm rms
  • L1 C/A code measurement error < 1.3 m rms
  • L1&L2 P code measurement error < 2.7 m rms
  • L2C code measurement error < 1.2 m rms
  • E1 code measurement error < 1.1 m rms
  • E5a code measurement error < 0.24 m rms

All values for elevation >15°

Time to first fix:

  • Warm start < 90 s
  • Cold start < 15 min GPS; <40 min GALILEO

Physical / Environment

Electronic box:

  • Size: 280x240x81 mm3 ; Weight: 3.0 kg
  • Operating temperature: -30º C to +60º C (qualification level)
  • Minimum switch-on temperature: -40° C (qualification level)
  • Radiation: Cumulative dose >50 kRad (Si)
  • Latch-up threshold > 70 MeV/mg cm2
  • Power consumption: 15 W avg.

Antenna (recommended for POD):

Patch Excited Cup antenna with optimized multi-path perfomance:
- Size: Ø 200 mm, h: 87 mm ; weight: 735 g

Other antennas available upon request


RUAG has delivered 22 flight models of the heritage receiver, a GPS Precise Orbit Determination Receiver based on AGGA-2 and LEON ASICs:

  • for the Swarm earth-observation mission of ESA, which is based on three satellites flying in formation with a common launch in 2013
  • for the Sentinel-1, Sentinel-2 and Sentinel-3 A/B satellites of ESA’s and the European Commission’s Copernicus program (6 satellites)
  • for the ESA/JAXA mission Earthcare
  • for NASA's mission ICESat-2

Currently , as of mid Feb. 2016, 12 of these 22 delivered flight models have been launched and are operating flawlessly in orbit to the full satisfaction of the customers.

For the successor, the subject PODRIX GNSS receiver, first flight model orders have been received, with first deliveries in Q1 2017.