[time-nuts] WAAS.....

[Magnus Danielson]

Hi,

On 08/01/14 16:33, ziggy9+time-nuts at pumpkinbrook.com wrote:
> I thought I had seen something regarding this before, and sure enough here it is:
>
> <http://www.freqelec.com/gps_gnss/waas_for_telecom_wp_5-06.pdf>
> <http://hugofruehauf.com/pdf/24-WAAS_for_Telecom_2003-upd_2011.pdf>
> <http://www.dtic.mil/dtic/tr/fulltext/u2/a485380.pdf>
>
> All variations on the same idea - essentially point a DBS dish at a WAAS satellite. Indications are that WAAS alone can be used for timing and the articles specifically touch on GPS backup and jamming resistance. Each article is a bit different so suggest reviewing all of them.
>
> I guess it's an open question if your receiver can use WAAS alone for timing. I don't have one to test with, but does anyone know if the LEA-6T supports this mode? It would seem so.

Well, if you dip your nose into the WAAS specification

http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/techops/navservices/gnss/library/documents/media/waas/2892bC2a.pdf

You will find that it has messages holding it's own orbit (message type 
9) as well as deviation from WAAS system time and UTC correction 
parameters (message type 12).

Using a surveyed position, aiming an antenna at a WAAS bird and then 
using a one-channel receiver should be achievable. A benefit of the WAAS 
signal is that by directing a channel to a WAAS rather than a GPS bird, 
you do not loose the navigation-contribution of that channel, but you 
gain the additional correction material, thus doing so should be a net 
gain with a rather small loss.

Anyway, I think looking at the actual signal spec gives better knowledge 
than just looking at derivative work.

Cheers,
Magnus