WAAS changes

[thataway]

On July 31, 2007, the FAA will decommission WAAS satellites 122 and 134, leaving satellites 135 and 138 for WAAS differential corrections in North America.

Some GPS receivers with a WAAS application, shipped before April 2007, the WAAS firmware does not recognize satellites 135 and 138. You may want to check your CPS and see if it still is getting the WAAS signals.

[Dreamer]

Thanks Bob,

For the last 2 days, Aug 1-2, my GPS has taken a long time to initialize. May be worth looking into. Raymarine E-80 with GPS 125.

[matt_unique]

My GPS is several years old and not WAAS enabled and it has also taken a long time to acquire the sat's. A buddy of mine had the same problem on his boat. It must not be specific to WAAS systems.

I remember reading this thread before I went out last Saturday (August 4).

Thanks for the heads up.

[thataway]

I just went and turned on the two Chart plotters on the TC 255. The Lowrance LCX 26 took 25 seconds to acquire fix, the Standard Horizon took 20 seconds to acquire a fix. The Lowrance was non WAAS; the Standard Horizon picked up 138 and gave a valid 3D WAAS fix. I will check the Garmin 492 on the CD 25 when it cools off (The Tom Cat is kept air conditioned..

Both the Standard Horizon and the Lowrance are about 15 months since I pruchased them.

[thataway]

Turned on the Garmin 492 (2006 manufacture date, but purchased about 3 months ago)--no WAAS signal--would not reconginze 138. Accurate fix and took 25 seconds for the initial fix. Reboot was 20 seconds.

Although WAAS is not available, this makes very little practical difference for most of our navigation. I am sure that all of the manufactuers will have a software update shortly.

[AnchortownJim]

Got on Coho last last night in the driveway and plugged in my '03 Garmin 2006 chartplotter to see if the recent satellite changes affected my receiving the WAAS GPS corrections.

Turned it on and after about 10 minutes, I had acquired the WAAS signal and had GPS accuracy of 6 feet.

No complaints here, life is good.

Jim

[thataway]

Jim, What satellites was it picking up for WAAS correction? My 2006 date of manufacture will not pickup the latest satellites--I double checked today. The unit says "WAAS enabled" but it is not getting the satellite. The native SA off of GPS should give you the accuracy of 3 meters. Do you have a reference point (I assume that with the driveway you do). I often will let a GPS "drift" over a 24 to 36 hour peroid to see what the "trail" does. Often there is peroidically a position which is 50 or 75 feet off. But the average accuracy is within 3 meters.

Thanks

[Doryman]

What is GPS 125? When I google it I get lots of references to products that support it but no references to explanations of what it is. I have a Raymarine E-80 and a Lowrance iFinder H2Oc (says GPS+WAAS) handheld. It is the latter that I am wondering whether I bought obsolete technology (at the SBS last January).

Thanks,
Warren

[TyBoo]

Now I'm all confused. I fired up both my Garmin units this morning (2006C, software upgrade in '05; 3210, new in '06). Both units acquired initial signals in the normal length of time (~15 secs) and both locked onto WASS about 10 seconds later. Accuracy to 9' claimed on both. Everything seems like it always was. I didn't find a way to determine what satellites they were using for the WASS differential. They both just said they were using it. They got me out to the ocean and back, so I guess I'll just leave them be.

[thataway]

On the start up screen the garmin shows the satellites which it is recieving. FAA decommissioned WAAS satellites 122 (#35) and 134 (#47), and brought on line: 135 (#48) and the new 138 (#51). My 492 was not showing #48 or 51 when I last checked.
Panbo suggests that the new Garmin will recoginze these satellites in time:
http://www.panbo.com/ look at the August 6th posting. His 4212 did not recognize them initially, but then a later posting, he found #51 on a Garmin 545 with the "D" over the bars of signal strength. He has a photo of an older RayMarine A60 taken simultanously which does not show #51.
#51 will be for the East Coast, and most likely #48 for the West coast. Ben Elison is on the East Coast--and I should show the same as he has.

As I noted my Lowrance didn't pick up the Differential satellite, but my Standard Horizon does (this was a few days ago)--My Garmin 492 did not--but I may turn it back on and check again.

Not having WAAS will make little if any practical difference. You will probably still have a position accuracey within a few meters--so not to sweat.

Warren, The RayMarine E80 is their state of the art--either it will pick up the appropiate satellite which gives the correction for WAAS, or not. If not, then RayMarine will allow you to down load soft ware which will. We should all check our manufacture's web sites for any updates on the chart plotters--they all have free down loadable updates for current, and usually for the last 5 years models. The I finder is also a good unit and up to date.

The Raymarine Antenna/GPS reciever is the GPS 125 module. It is just a reciever/antenna which plugs into the unit--it will be fully capable of recieving the signal of any satellite with the proper format and frequency, that the RayMarine 80 is programed to recieve.

It is very possiable if I were to leave my recievers on for a long peroid of time that the almanac will self correct and recieve the new WAAS satellites.

The Differentail GPS is of two forms--one is the ground station, which is the old lighthouse beacon frequencies and requires a separate reciever and antenna. The WAAS was developed for aircraft--apparently not working out as they had hoped--and relies on a series of ground stations which recieve the standard GPS signal, then correct it by their known position and relay this information to two satellites which cover the US--these two satellites were changed by the government recently. This correction is sent to your reciever, and then it makes the correction--usely a few feet at the most...In some places up NorthEast it actually degraded the position at first.

Again--don't sweat the differential/difference!

[thataway]

Ok,
I left the Garmin 492 and a 176 C (about 4 years old) on for a peroid of time. They both acquired Satellite #51 (138) and the Differential was working. So the conclusion is that at least any Garmin built in the last 4 years will pick up the new Differential satellites. This assumes that the West Coast Satellite is also picked up--which it seems to be, based on Tyboo's experience.

I have an old Lowrance 3500--about 5 years old. In 20 minutes it didn't pick up Satellite #51, but did pick up all of the other satellites. It showed an "Accuracy" of 68 feet--the Garmin showed 9 to 11 feet. Frankly these numbers may not be valid--but give some indication of susposed accuracy. I will leave the Lowrance on for a longer time and see what happens. Edit: upon leaving the Lowrance 3500 C on for an hour, it picked up WAAS correction, although it did not identify the satellite by number. The "accuracy" dropped in half to about 35 feet from 68 feet.

My assumption is that I didn't leave the 492 on long enough (it is on the CD 25 which is not in the water--the TC is the boat being used currentlly) to acquire the new satellites.

To see if the satellites are picked up--hit "menu" twice on the Garmin instruments. Scroll to "GPS" at the top of the column on the left side of the screen. That should show a circle with the relitative positions of the satellites and a bar graph which would show the number of the satellite and relitative strength.

Only checking will tell us which GPS plotters will pick up the new satellites.
You may have "WAAS" "on" . Some plotters will not get a fix when it is "WAAS" on is enabled, if there is no satellite to give the differential fix.
This may account for some plotters taking 10 minutes recently to acquire a fix--it may take this time to update the almanac of GPS satellites, if the unit will...

[TyBoo]

[thataway]

I am far from an expert on the GPS satellites and their future. The PRN number (PSEUDORANDOM NOISE) is one identifier of GPS satellites. The two "new" satellites are PNR 135 and 138--PRN 135 is Galaxy 15 at 132.9 West, # 48 on most of our GPS units and PRN 138 is Anik F1 at 107.25°W, # 51 on most of our GPS units. Both of these satellites seem to also carry TV signals, plus some military materials. The previous satellites carrying WAAS were considerably further to the West, so uppper North West US and Canada was poorly covered.

The FAA bulleting states:
"New WAAS GEO Status as of 7/13/07 (final update because GEO are operational)
INTELSAT(PanAmSat), Galaxy-15, W133 deg, PRN -135 (48)
PRN-135 was taken out of "Test Mode" and placed in normal mode at 08:00 UTCon 11/9/06. PRN-135 ranging quality is set to "not monitored". PRN-135 rangingintegrity will be improved to NPA quality, then PA quality as operational experience is gained and planned WAAS software upgrades are fielded during the 2nd half of 2007

Telesat, ANIK-1fR, W107.3 deg, PRN -138 (51) PRN-138 was taken out of "Test Mode" and placed in normal mode at 15:21:00 UTC
on 7/13/07. PRN-138 is operating as a NPA quality ranging source. PRN-135 ranging integrity will be improved to PA quality as planned WAAS software upgrades are fielded during the 2nd half of 2007.."

[Da Nag]

[Doryman]

Thanks, Bill. Wonder if they will notify us when the upgrade is available.

Warren