WAAS enabled?

Freddo · Post by **Freddo** » 19 January 04 2:08 pm

Has anyone tried enabling the WAAS on their GPS?

I can now get differential correction on some sats. When did this happen? Is it really useful?

Some feedback would be appreciated.

Bronze · Post by **Bronze** » 19 January 04 2:43 pm

Last I heard (July 03) it did work in Au.

Bronze.

Ebenezer · Post by **Ebenezer** » 19 January 04 3:45 pm

Hmm. I know Japan have a satellite that provides the data, but afaik there is no correction data from any ground stations in Oz. Thus the data does not improve the accuracy. Perhaps this has changed?

swampgecko · Post by **swampgecko** » 19 January 04 4:20 pm

Lat info I had seen on WAAS was only in the topend that it was available, because thats were the satellite was "visable" from.

WAAS does increase accuracy a fair bit. My belief was it also used radio and tv signals to refine the positioning..........

As for the rest of AUssieland... no idea

Ebenezer · Post by **Ebenezer** » 19 January 04 5:02 pm

WAAS like satellites (WAAS is the US system, EGNOS is the European one, MSAS is the Japanese one) are satellites in geostationery orbit that provide correction information for the "normal" GPS satellites.

In a rough sense this is similar to other differential GPS systems. There are systems that use ground based transmitters (such as carriers in radio & tv signals) to transmit the corrections, but WAAS does not use this.

For the correction information to be useful you need to be situated near a ground station that calculated the correction information. Of course, you also need to be able to receive the correction information.

With a clear view of the horizon to the North you should see the MSAS satellite from Australia (although the further North you are, the higher in the sky it will be). The crunch comes with the distance to the nearest ground station providing correction information. Afaik the MSAS satellite only receives correction information from ground stations in Japan. Basically we are so far away here from the nearest ground station that the correction information is not accurate enough.

Some more information here: http://gpsinformation.net/exe/waas.html