Topnet Live: Starpoint/Skybridge general information

This is general information about Topnet Live Starpoint and Skybridge.

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Topnet Live: Starpoint/Skybridge general information

Precise Point Positioning (PPP): What you need to know

PPP: What is it?

Precise Point Positioning (PPP) is a positioning technique that utilizes all available GNSS constellations (depending on the service). It combines precise satellite orbits and clocks with undifferenced dual-frequency observables. PPP can provide position solutions at centimeter-level precision using a network of reference stations around the world. In areas where a traditional real-time kinematic (RTK) network does not exist, PPP is a viable solution that enables the user to collect data nearly as efficiently as network RTK using a single GNSS receiver.

How it works

PPP differs from double difference relative positioning used in RTK in that it does not require the observation of the same set of satellites as observed by the base station. PPP provides absolute positioning information to the rover with respect to the base stations. The PPP rover receives precise orbit and clock data information from the processing center, which is connected to a sparse network of reference stations.

Time to solution

It will take up to 10-30 minutes for the PPP solution to converge when used in standalone mode.

Currently, MAGNET Field performs base estimation when using Skybridge to determine transformation parameters. Until this is complete, the user will not be able to switch into PPP mode. This process takes approximately 25-30 minutes to complete.

Please note that while the PPP solution is converging, you are still able to survey with RTK. The ability to continue surveying when the RTK corrections are lost will not be available until base estimation is completed.

There are 3 types of PPP solutions used in MAGNET software:

  • CPPP (Convergence Point Precise Positioning): A convergence stage of calculation of autonomous coordinates of a single receiver, when using dual frequency code and carrier phase measurements and the data on precise orbits and clocks of navigation satellites.
  • PPPN (Point Precise Positioning Normal): Positions are calculated using dual frequency code and carrier phase measurements of a single GNSS receiver and the data on precise orbits and clocks of navigation satellites. Integer ambiguities, however, were NOT fixed (their FLOAT estimates were used instead).
  • PPPF (Point Precise Positioning Full): Positions are calculated using dual frequency code and carrier phase measurements of a single GNSS receiver and the data on precise orbits and clocks of navigation satellites. Integer ambiguities were FIXED.

Datum used

Currently PPP uses ITRF 2014 Epoch 2010.0.

ITRF 2014 employs velocity models. Transformation parameters from it to WGS 84 are currently not available. If using standalone PPP on a project that has known coordinates, a localization (one-point minimum) will need to be performed to determine the transformation parameters to the project.

When using Skybridge, the base estimation in the software will be performed to the datum currently specified, which will determine the transformation parameters.

Starpoint Pro

Starpoint Pro is Topcon's stand-alone PPP subscription from Topnet Live. This allows the user to survey using the PPP technique anywhere they can receive the corrections. Currently Topcon is offering two options for receiving the PPP corrections: L band and NTRIP. L band is a satellite-based correction service. 

Corrections are transmitted in the L band frequency range. This method can be used anywhere in the world that the L band satellites are visible. This is meant for land-based applications only, not marine-based.

PPP solutions available are CPPP, PPPN, and PPPF.

NTRIP in distributed via the internet. 

This method can be used where access to Topnet Live is available. It will not be available if the internet connection is lost. This can be used in land-based and marine applications.

PPP solutions available are CPPP and PPPN.

Skybridge/Skybridge Pro

Skybridge/Skybridge Pro is Topcon's PPP solution subscription that augments RTK when connection to the corrections is lost. It can also be used as a standalone PPP service. Skybridge is GPS+GLO only, and Skybridge Pro is full wave. Skybridge Pro can only be used as RTK infill up to 20 minutes. The user must start with an RTK survey. Infill occurrences can be unlimited but no longer than 20 minutes for each one. Skybridge Pro can be used as unlimited infill OR PPP standalone without using RTK. Currently Topcon is offering two options for receiving the PPP corrections: L band and NTRIP. L band is a satellite-based correction service. 

Corrections are transmitted in the L band frequency range. This method can be used anywhere in the world that the L band satellites are visible. This option allows the user to use the augmentation on non-Topnet Live RTK networks.

PPP solutions available are CPPP, PPPN, and PPPF.

The subscription for this service is tied to the receiver.

When the subscription is enabled, the receiver must be receiving satellites for the activation to succeed.

NTRIP is distributed via the internet. 

This method can be used where access to Topnet Live is available. It will not be available if the internet connection is lost.

PPP solutions available are CPPP and PPPN.

The subscription for this service is tied to the receiver.

When the subscription is enabled, there is no requirement for the receiver to be receiving satellites.

What do I need to use PPP?

To use the Topcon PPP subscriptions, you will need the following:

  • A receiver that is capable of all constellations and L band, for example:
    • Topcon: HiPer-HR, HiPer-VR, NET-G5, or MR-2
    • Sokkia: GNR5 or GRX3
  • Receiver OAF upgrade that includes VPPP, CYRP, and SPPP options
  • GNSS firmware 5.4 or higher
  • Subscription to Starpoint Pro or Skybridge Pro
  • MAGNET Field v7.1 or higher.​ Please note that Topcon Pocket 3D and Topcon 3D-MC are not currently supported.

PPP survey configurations available in MAGNET Field

  • Standalone PPP using correction received from the L band satellites
  • Standalone PPP using corrections received from the Topnet Live network
  • Base and rover RTK with PPP using correction received from the L band satellites
  • Network RTK with PPP using correction received from the L band satellites
  • Does not require connection to a Topnet Live network
  • Networks such as the Ohio DOT VRS work very well
  • Network RTK with PPP using corrections received from the Topnet Live network

MAGNET Field status of the PPP subscription messages

With a Starpoint subscription, the field can display the following values:

  • NOT READY: The subscription is absent, or the date of the subscription is expired
  • READY: The current subscription properly works
  • L band Satellite: Name of the current satellite
  • L band Signal Quality: The received power level, in dB
  • L band SNR: The current signal to noise ratio, in dB*Hz

MAGNET Field status of the PPP solution messages

In Skykridge status, the field can display the following values:

  • Unknown: Unknown status
  • Rover Not Ready: The rover receiver is not ready to work in the Skybridge mode. Please check the receiver options, Starpoint subscription, and satellite tracking
  • No Base Data: The rover receiver does not obtain the correction data from the network or RTK base station. The rover is not ready to work in the Skybridge mode
  • Base Estimation: The estimation of base station coordinate is run. The rover is not ready to work in the Skybridge mode
  • Ready: The rover receiver is ready to work in the Skybridge mode

FAQs

  • Does Pocket 3D support PPP?
    • No, currently Pocket 3D does not support the use of PPP.
  • Does 3D-MC support PPP?
    • No, currently 3D-MC does not support the use of PPP.