Menu Sign In Contact FAQ
Banner
Welcome to our forums

Has anyone ever seen a handheld GPS receive EGNOS reliably, or at all?

Never saw it on the Garmin 496.

Now testing the Aera 660. Admittedly in a hangar but…


Administrator
Shoreham EGKA, United Kingdom

Peter,

It does not appear that you were receiving the SBAS signals from an EGNOS satellite. They will have satellite numbers greater than 32 and I would expect the “3D GPS Location” status indication to add “Differential” somewhere. Here is a screenshot of my GPMAP 696. Note satellite 48 is a WAAS satellite. There are three WAAS satellites, only two of them 48 and 51 also have a GPS ranging signal as well as providing the SBAS corrections. An SBAS satellite that is not providing a ranging signal will have a hollow signal bar.

KUZA, United States

Interesting. Many thanks.

I have just extracted the Garmin 496 out of the plane (been replaced in the yoke with the Aera 660) and this is what I got


About 10 mins later, finally…

Funny thing is that I don’t recall ever seeing EGNOS in flight. There the 496 was using the dash-top antenna. In the above it was using the short (3" long moulding) external antenna.

Also the EGNOS channels never go green.

I did some tests with the GPS location relative to the house and clearly the satellite is to the south, because any obstruction to the south kills it completely.

Administrator
Shoreham EGKA, United Kingdom

Peter wrote:

I did some tests with the GPS location relative to the house and clearly the satellite is to the south, because any obstruction to the south kills it completely.

Like all geostationary satellites, it hangs over the equator. It’s pretty low above the horizon, too.

LKBU (near Prague), Czech Republic

Haven’t we had this before?

I remember many (7-8?) years ago, when there was only one EGNOS satellite, I put my tiny Garmin Pilot 96C handheld on the rooftop, and after doing its thing for about 10 minutes, it came up with “WAAS” announcement and a high satellite number on the status page, and quite likely, a very accurate position. However, in daily use (when flying) I do not think I ever saw it announce “WAAS”.

The equally old Garmin 196 and, I believe, alle Garmin x96’s since then have been WAAS-capable. And they acquire the EGNOS signals better than my old 96C.

This – SBAS/WAAS/EGNOS – is one (small?) thing we’re missing now that we’re all using smartphones and iPads to navigate handheld, with very few dedicated aviation handheld GPS’s in use anymore.

Ultranomad wrote:

It’s pretty low above the horizon, too.

Well yes, hanging 36.000 km above the equator, they are low if you’re far north, they are indeed below the horizon if you are on Svalbard, which is why they will not get any LPV approaches up there. Even in “continental” northern Scandinavia EGNOS assisted procedures are limited, also because of mountains blocking the EGNOS signals. Instead Norway has started using GBAS and flying GLS approaches. But that is not for GA, not anytime soon.

Last Edited by huv at 12 Jan 13:05
huv
EKRK, Denmark

Actually, the advantage of EGNOS is not as dramatic now as it was 7-8 years ago. The new civilian signals (L2C, L5, L1C) being broadcast by the main GPS constellation improve the positioning accuracy a lot. Not to the level of EGNOS, but, I dare say, to a level sufficient for piston GA.

LKBU (near Prague), Czech Republic

Peter wrote:

Also the EGNOS channels never go green.

That just means they are not providing the GPS ranging signal. In the, two of the WAAS satellites can also be used like they are additional GPS satellites since they provide both signals.

See this site. It shows instantaneous EGNOS HPL and VPL. A VPL <=35 meters supports LPV 200 DH. EGNOS real time status

Note the PRN numbers for the EGNOS satellites. They are always offset by 87 from the number presented on the GPS. So PRN 120 shows as 120-87=33 on your GPS.

KUZA, United States

Ultranomad wrote:

Not to the level of EGNOS, but, I dare say, to a level sufficient for piston GA.

The airlines have not adopted SBAS, so GA is the main aviation user of SBAS. Receivers are not commercially available to use dual frequency as of yet to take advantage of L5. SBAS has two main advantages, 1) it is not dependent on RAIM for integrity and 2) the accuracy and integrity support LP and LPV approach types.

KUZA, United States
8 Posts
Sign in to add your message

Back to Top