waas

[hihosland]

Is the WAAS system operational in Australia or is it limited to the footprint of the special satelites in geo stationary orbit over North America?

 

Just curious

 

Davidh

 

 

[Guest pelorus32]

Hi David,

 

I had a similar question recently. My research suggested that it was North America only. In Europe the equivalent is EGNOS. AFAIK there is no Australian augmentation system yet. See this:

 

Currently, WAAS satellite coverage is only available in North America. There are no ground reference stations in South America, so even though GPS users there can receive WAAS, the signal has not been corrected and thus would not improve the accuracy of their unit. For some users in the U.S., the position of the satellites over the equator makes it difficult to receive the signals when trees or mountains obstruct the view of the horizon. WAAS signal reception is ideal for open land and marine applications. WAAS provides extended coverage both inland and offshore compared to the land-based DGPS (differential GPS) system. Another benefit of WAAS is that it does not require additional receiving equipment, while DGPS does.

 

From that foray into the ether I also found this:

 

WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal.

 

The issue in Australia is the ground piece of the puzzle apparently.

 

We have differential ground stations but not WAAS.

 

Others may have more specific detail but that is what I took from my research.

 

Regards

 

Mike

 

 

[hihosland]

Thanks Mike

 

my looking brought up the following from the ASTRA (the Australian Strategic Air Traffic Management Group) web site

 

T

 

Frequently Asked Questions

 

TSO 145/146 receiver and WAAS

 

Is the TSO C-145/6 GPS receiver able to use WAAS. The signals come from INMARSAT POR, and are available Australia wide." Does this mean that Australia has a network of Wide Area Reference Stations (WRS) providing data to a Wide Area Master Station (WMS) which is processing and uploading the correction data to INMARSAT?

 

No, Australia does not have a network of ground monitoring stations providing data up onto the POR Inmarsat. However, the TSO 145a/146a receivers can make use of the Ranging signal from the POR; this is equivalent to having an extra GPS satellite always in view. This adds a useful increase in the availability of high accuracy signals.

 

Does it mean we have an Australia wide WAAS capability that has yet to be implemented?

 

There are no plans to implement WAAS in Australia at this time. The Japanese are well advanced with their equivalent system (MTSAT). Australia (just) might make arrangements to provide WAAS like services using MTSAT; there are no plans at this time to pursue this possibility.