AutoGNSS

In this website you will be able to compute your GNSS data online. The processing core is rtklib.

Two different approaches are available:

• DDs: Relative positioning, based on the double differences model respect;
  • EPN Network (subset of stations)
  • Active BFA's Network
  • Active GFA's Network
  • CatNet Network
• PPP: Precise Point Positioning with phase measurements, PPP-based.

Use standard RINEX/CRX names (8.3/10.3 for RNX v2.x or LONG for RNX v3.x). IGS-style compression (.Z or .gz) is also allowed.

Main processing options:

• Sampling rate: 30 s (all observations in PPP).
• Elevation mask: 5 deg.
• Ephemeris, clocks: CODE precise ephemeris used (rapid if finals are not availaible).
• GNSS systems: GPS, Glonass and Galileo.
• Ocean loading:
• DDs: FES2004 coefficients of the reference station used by default for the roves. User coefficients, if provided, will be used.
• PPP: FES2004 coefficients avalable for all the reference sites. User can use own values for any site.
• Receiver/antenna model, eccentricities,...: extracted from the RINEX header.
• Ionosphere: iono-free code/phase combination used.
• Troposphere: GMF and ZTD+horizontal gradients estimated.
• Reference frame/antenna PCV model:
• IGb08+IGb08.ATX: for observations before GPSW 1934 (2017-01-29). No IGb08-IGS14 corrections applied to the positions due to the IGb08.ATX-IGS14.ATX antenna values change.
• IGS14+IGS14.ATX: for observations after GPSW 1934 (2017-01-29).
• ETRF2000 (epoch 2010.0): for DDs, using the ATX file valid for the observation epoch.

Some general recommendations for the time span of the observations:

• GNSS receivers (benchmarks) should be located in places with clean horizon and no obstructions. Take special care to avoid nearby signal reflecting surfaces (might cause multipath).
• Some remarks:
• PPP: use daily observations to get cm-level accuracies.
• DDs: try to span the sessions as much as possible, regardless the convergence time. In normal conditions,
• After about 1 hour: 3D positions converge within 2 cm respect the daily solution. However, at least 2 hours of data should be used.
• If the distance to the reference station is >100 km, try to get a PPP solution instead.
• If the height difference to the reference station is >300 m, try to get a PPP solution instead. Biases in the Up component could occur due to the large ZTD variations between the reference and the rover station.

Achievable accuracies examples: (solutions compared with Bernese outputs, on a summer day to have large ZTD values):

Very short baseline (2.5 km), height difference: 20 m
Short baseline (11 km), height difference: 187 m
Medium length baseline (25 km), height difference: 67 m
Medium-large baseline (89 km), height difference: 1804 m PPP would be best.
Large baseline (180 km), height difference: 871 m Similar to PPP.
Large baseline (308 km), height difference: 2097 m PPP would be best.

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