[talk-au] Increased precision options for Australia - QZSS, SBAS or Galileo

Andrew Davidson theswavu at gmail.com
Tue Jun 12 10:29:39 UTC 2018

On 12/06/18 20:04, Leith Bade wrote:
> Our receivers work fine in Australia as I live in Canberra and work for 
> the Swift Navigation engineering department. Using one of the free CORS 
> stations here I can get 2cm positions from my car. Mind you the setup 
> cost ~$2000.

This is the bit I'm a bit dubious about. The blurb on GA suggests that 
we are going to be getting 3cm accuracy from our smart phones, but I'm 
wondering how the development of GPS antennas small and cheap enough to 
go into phones is coming along.

> Unfortunately OpenStreetMaps only uses "WGS84" as it's datum which is 
> not that well defined compared to a surveying datum like GDA94/2020 or 
> ITRF, and most existing data has only been measured to a few metres (at 
> most). So I wouldn't worry too much about the drift as there are other 
> larger sources of error in OpenStreetMaps.

Reminds me of a paper I read on the the subject where the author pointed 
out that anyone who says they are mapping to "WGS84" doesn't know what 
they are talking about. However, I do think you are being a little 
pessimistic. So long as there is good aerial photography or some 
external dataset available it's possible to get closer. In Canberra, 
provided that the mapper traces carefully, you can easily map things to 
within 0.3m.

More information about the Talk-au mailing list