PositioNZ - Post Processing Service

The LINZ PositioNZ Post Processing Service (PositioNZ-PP) is a free automated service that processes GNSS data to obtain NZGD2000 coordinates.

PositioNZ logo

It creates time savings for surveyors by providing highly accurate positioning information based on LINZ’s national network of continuously operating reference Global Navigational Satellite Systems (GNSS) stations. It means users do not need their own specialised GNSS processing software.

To use PositioNZ-PP, customers upload GNSS RINEX files collected at survey marks that require coordinates. PositioNZ-PP processes each file individually and sends results by email.

Results are provided in the official geodetic datum NZGD2000, which incorporates the NZ deformation model, and the national vertical datum NZVD2016. International Terrestrial Reference Frame coordinates are also provided (ITRF2008 and ITRF96). 

Submit GNSS data for processing

PositioNZ-PP Input Data

RINEX Version

2.11

Observations

GPS data at 30 second epochs.

Accepted session length

1 hour to 48 hours (recommend at least 4 hours)

Antenna and Receiver information

Refer to IGS Conventions

RINEX Height

Vertical distance between antenna reference point (APR) and top of mark

Service Range

New Zealand only

Occupation length and accuracy

The accuracy of PositioNZ-PP coordinates depends primarily on occupation length. If there is a requirement for the survey to comply with a particular LINZ accuracy standard (for example, if Order 2V heights are needed), then the control framework marks will also need to be separated by at least the minimum distance specified, so that distance-dependent accuracy standards are met. The table below outlines the occupation length (for each of two independent occupations) and distances between control framework marks for various levels of accuracy commonly required for control framework surveys.

East and north accuracy (95% confidence level) (m)

Height accuracy (95% confidence level) (m)

Minimum distance between control marks (m)

Minimum time for each occupation (2 occupations for each mark required) (hours)

Order

Local (vector between control marks)

Network (coordinate in terms of PositioNZ stations)

Local (height change between control marks)

Network (height in terms of PositioNZ stations)

NZGD2000

NZVD2016

0.010

0.005

0.015

0.010

4000

16

3

1V

0.010

0.005

0.015

0.010

1500

16

4

2V

0.020

0.015

0.030

0.020

3000

4

4

2V

0.020

0.015

0.030

0.020

300

4

5

3V

0.030

0.020

0.050

0.040

700

3

5

3V

0.040

0.030

0.060

0.050

1500

2

5

3V

Table 1: GNSS occupation times and orders achieved using PositioNZ-PP for common geodetic accuracy specifications and control framework mark spacing.

Example 1:  If heights with network accuracy of 2cm or better are required and there is 500m between control framework marks, then two 4-hour occupations at each mark are required and the coordinates will achieve Order 5 (NZGD2000) and Order 3V (NZVD2016).

Example 2: If the height change accuracy between control marks (ie local accuracy) needs to be better than 3cm and there is 3km between marks, then two 4-hour occupations at each mark are required and the coordinates will achieve Order 4 (NZGD2000) and Order 2V (NZVD2016).

RINEX data

PositioNZ-PP requires RINEX v2.11 data, which most GNSS processing software is able to produce.

A separate RINEX file is required for each independent occupation at each mark. The typical epoch interval for PositioNZ-PP data is 30-seconds. Files with smaller intervals (such as 1-second data from a RTK base station) can still be submitted and will be converted to 30-second data. The maximum file size is 30mb.

All heights provided in RINEX files must be vertical measurements between the top of the survey mark and the Antenna Reference Point (ARP). The ARP is almost always the lowest point/surface on the antenna. The GNSS software from which the RINEX is exported should be checked to ensure it is set to produce heights to the ARP.

RINEX files contain a header section at the top with important metadata that is used to correctly process the data. When exporting GNSS data in RINEX format, it is particularly important that the following information is set correctly:

RINEX Label

Description

MARKER NAME

A unique name for the mark, such as the geodetic code

ANT # / TYPE

The antenna type is used with the antenna phase centre models in PositioNZ-PP to reduce the data to the ARP. The IGS standard antenna code should be used, otherwise PositioNZ-PP may not recognise the antenna and will calculate incorrect heights.

APPROX POSITION XYZ

The approximate XYZ position should be accurate to a few metres. PositioNZ-PP uses it as an initial coordinate for the processing. For existing geodetic marks, this can be checked by converting the NZGD2000 coordinate in the Geodetic Database to ITRF2008(XYZ).

ANTENNA: DELTA H/E/N

The vertical antenna height is used to reduce the data from the ARP to the top of the survey mark.

Subscribe to PositioNZ-PP mail list

PositioNZ-PP uses models based upon the daily positions of the LINZ PositioNZ stations, which are updated periodically.  The models will also be updated shortly after a significant earthquake.  If you would like to know when PositioNZ-PP has been updated please subscribe to PositioNZ-PP updates by sending an email to positionz@linz.govt.nz with “Subscribe to PositioNZ-PP” in the subject line.

Subscribe to the PositioNZ newsletter and station notifications 

PositioNZ-PP help

Please check the post-processing service help information attached below.

If you are experiencing problems and need some help or would like to submit feedback, please e-mail positionz@linz.govt.nz with "PositioNZ-PP feedback or issue" in the subject line.

Last Updated: 17 November 2017