[time-nuts] RTS

[Jim Lux]

On 4/4/13 12:51 AM, gary wrote:
> Isn't this what WAAS does?
>> http://igs.bkg.bund.de/ntrip/about
>


Yes..

There's lots of ways to get real time (or near real time) correction 
data. WAAS is but one.  TASS (experimental) is another.  There's various 
and sundry local High Accuracy Reference Networks (HARN) around, some 
run commercially, some run by governments.  Heck, you used to be able to 
subscribe to corrections broadcast on a FM broadcast station subcarrier 
like stock quotes and sports scores.  These days, "the internet" is 
probably the preferred medium.

Different corrections are in different formats for different end uses. 
If you are flying a plane, you only need "meters" kind of accuracy and 
you're probably using a L1 only receiver.  If you're doing real time 
kinematic surveying, you are looking for 1mm sorts of accuracy, so a 
local reference station (or a synthesized reference station) would be 
handy for taking out smaller ionospheric and solid earth tides kinds fo 
things.

There are also lots of folks distributing corrections and reference 
data.  In the US there's commercial providers, so federally funded data 
providers have to be careful about "government doesn't compete with 
industry" rules.  For instance, to get the JPL precision data, you need 
to have an account and certify you're using it for educational and 
research purposes, and not as part of a commercial enterprise.  In other 
countries, they just put it out there for anyone to use.

It's like mapping data, the availability of which (for free) varies a 
lot from country to country.

{Political comment:  I think that mapping and precision geodesy data is 
a common good or infrastructure. It's an appropriate use of tax money to 
provide universal access because there isn't a "business case" to cover 
everything with equal performance. A fine example is USGS topographic 
maps and NOAA Marine Charts. }