DFMC SBAS
L1 SBAS delivers corrections for 1 satellite constellation and signal. For example, SouthPAN, WAAS and EGNOS send corrections for GPS L1.
Dual-Frequency Multi-Constellation (DFMC) services offered by next-generation SBAS deliver corrections for 2 satellite frequencies (L1+L5) and 2 satellite constellations (in SouthPAN’s case, for GPS and Galileo). This service supports improved positioning to ≤1m horizontal and ≤2.5m vertical (95% confidence interval).
The combination of 2 frequencies enables the GNSS receiver to self-correct for atmospheric errors that affect signals. DFMC provides improved integrity and precision and is a standard for future SBAS. It was demonstrated during the SBAS test-bed in Australia and New Zealand.
Find out more about the SBAS test-bed trial
PVS
Precise Point Positioning (PPP) is a high-accuracy positioning technique used in commercial services and open services such as QZSS Centimetre-Level Augmentation Service (CLAS) and Galileo High Accuracy Service (HAS).
PPP Via SouthPAN (PVS) is a high-accuracy service that improves position accuracy to ≤0.40m horizontal and ≤0.55m vertical (95% confidence interval). Full position accuracy is achieved after a convergence period better than 80 minutes during PVS early Open Services. The user does not need to remain stationary during the convergence period.
For information on the performance of PVS, see the SouthPAN Service Definition Document and SouthPAN early Open Services factsheet.
PVS signals
PVS is being transmitted through SouthPAN’s L5 navigation signal. PVS corrections will also be transmitted via the internet. The PVS correction messages are applicable to:
- GPS L1 C/A and L5 signals
- Galileo E1 and E5a signals.
In the future, PVS will transition from SouthPAN’s L5 navigation signal to a new L5b navigation signal. The L5b signal has some advantages over L5, including high bandwidth so more correction data can be transmitted faster.
The transition is scheduled for 2027 when the first new SouthPAN satellite service (SouthPAN GEO Payload 01, known as SGP-01) comes online.
PVS new signal transition
The PVS early Open Service signal shares the L5 frequency with the DFMC SBAS Open Service signal.
SouthPAN PVS signal will transition to a new navigation signal centred on 1,207.14 MHz. The transition is scheduled for 2027. Toitū Te Whenua and Geoscience Australia will publish more information before transition.
PVS use
PVS-compatible GNSS receivers are not yet widely available. We are working with original equipment manufacturers (OEMs) to ensure support and availability of PVS compatible receivers for the Australia and New Zealand markets.
There are some receivers specifically built for the SBAS test-bed project that can utilise all 3 SouthPAN early Open Services. See the list of SouthPAN compatible devices.
It is also possible to use a software-defined radio (SDR) and PPP engine to decode the PVS correction signal for use with a supported GNSS device.
Differences between L1 SBAS, DFMC SBAS and PVS
L1 SBAS is the signal used in compatible GNSS devices since 2003. L1 SBAS were primarily designed as an integrity monitoring system for safety-critical operations in civil aviation. They were later adopted for other applications in a wide range of industries.
SouthPAN is a next-generation SBAS that also transmits a Dual-Frequency Multi-Constellation (DFMC) service augmenting 2 frequencies on each of GPS and Galileo. DFMC is an emerging standard for future SBAS as it provides improved integrity and position accuracy.
PVS is the Precise Point Positioning (PPP) Via SouthPAN Open Service that provides real-time orbit and clock corrections and additional signal bias corrections. This technique allows for more precise positioning but requires a convergence period for that precision to be achieved.
For information on the performance of each of these services, go to SouthPAN Service Definition Document and SouthPAN early Open Services factsheet.
Datum, signal transmission messages and signal performance
The SouthPAN Service Definition Document provides details on the reference frames used by SouthPAN, characteristics of SouthPAN early Open Service messages and the SouthPAN signal performance.
Accuracy and convergence times will improve as we add infrastructure to make the system fully operational.
PRN code
A PRN code is a unique code used by each GNSS satellite so that end user equipment can distinguish one satellite from the others. This is important because all satellites providing the L1 positioning service transmit on the same frequency: 1,575.42 MHz.
PRN means psuedo-random noise, which is a digital signal processing technique that makes weak signals easier to detect, as well as combining different data on the same frequency.
PRN 122 is currently used for the Australia and New Zealand SBAS service. When a second satellite is added to the SouthPAN network, this will have its own PRN.
Data access services
Internet delivery of SouthPAN services is described in the SouthPAN Service Definition Document for Data Access Services. Internet-delivered services provide SouthPAN corrections and require a compatible GNSS device with a clear sky view of the GNSS satellites to measure a position.