Relative Positioning

Sometimes you do not need to know your precise position but you do need to know your position or an object’s position, relative to another object or location. Our GPS and GNSS relative positioning solutions are used to:

  • Determine where an object is located on earth with respect to another object’s location
  • Determine the horizontal and vertical distances between one object to another object. (The horizontal and vertical distances can also be referred to as baseline lengths, displacements, relative separations or offsets between the two objects)

Applications requiring relative GNSS positioning include:

  • Landing systems such as helicopter to aircraft carrier
  • Railway collision avoidance systems
  • Autonomous in air refueling
  • Safety systems where a device beep increases in volume as you approach another object or location
  • Automated ship docking systems

Highlights

  • Ability to determine relative positioning between two or more moving objects
  • Calculation of relative baseline between two or more objects in a series
  • Real time and post-mission processed relative positioning solutions are available
  • Offered in GPS or GNSS standalone systems

What We Offer

 

Real Time GPS or GNSS Relative Positioning Solution:

ALIGN® Relative Positioning

  • Generates high accuracy heading, pitch, relative separation and positioning between two or more receivers for high precision monitoring and automation
  • Must have correction delivery method between ALIGN Master and ALIGN Rovers
  • The ALIGN Rover is positioned with respect to ALIGN Master. ALIGN Rover is referenced to the ALIGN Master, reducing the jitter and resulting in higher accuracy
  • Can use multiple ALIGN Rovers with a single ALIGN Master
  • ALIGN Master and ALIGN Rover position solutions can be requested on either or both ALIGN Master and ALIGN Rover
  • Position and heading solution can be requested up to 10 Hz

The figure below illustrates the Master receiver located on a marine vessel and the Rover receiver located on a fighter jet. Relative heading, pitch, baseline length and Rover position are computed with respect to the Master receiver.

 

 

Real-Time Kinematic (RTK) Relative Positioning

  • Generates high accuracy relative separation between two or more receivers for high precision monitoring and automation
  • Must have correction delivery method between RTK Base and RTK Rovers
  • The RTK Rover is positioned with respect to RTK Master. RTK Rover is referenced to the RTK Master, reducing the jitter and resulting in higher accuracy
  • Can use multiple RTK Rovers with a single RTK Base. Position can be provided on the RTK Rover up to 1 Hz

Post-processed Relative Positioning Solution:

Our Waypoint® moving baseline module GrafMov allows for GPS post-processing between two moving platforms. By processing directly between two moving kinematic objects, the accuracy of the relative trajectory can be improved significantly over that of a stationary base. This is especially true if the base station distance is much larger than the relative distance. If the two antennae are fix mounted, then heading can also be computed.

Post-processing takes advantage of both forward and backward data computations in order to generate the most accurate combined GNSS solution.

  • Relative Processing - All of the advanced features of our GrafNav software including forward/reverse/combined processing, dual- and single-frequency and fast processing speed are supported
  • Relative Vector Output - Our GrafMov software can export a number of relative vectors including local level, ECEF and range and bearing

Two GNSS receivers’ raw code and phase data can be post-processed in GrafMov to obtain relative positioning solutions. The forward post-processed solution is similar to the real time GPS or GNSS relative position determination system mentioned above.

Things to Think About

 

When choosing a relative positioning solution, consider the following needs of your application:

  • Solution accuracy
  • Signal availability
  • Solution rate
  • System dynamics
  • System price
  • System installation constraints
  • Real-time versus post-processed solution

     

Products

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High Performance GNSS Antennas

Performance of a choke ring antenna without the size and weight. Features high phase center stability and low phase center offset. Ideal for survey, ground mapping, agriculture, construction and mining, temporary and permanent reference station applications

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Receivers

OEM board level and board + enclosure GNSS receiver options

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ALIGN

Provides high precision attitude and accurate relative positioning information between two or more receivers in dynamic land, air and marine applications