enabling waas

[+paul6921]

do you keep waas enabled all the time if not why? i understand keeping it on all the time drains batteries faster is this true?give me a situation where you would enable it when geo-caching thanks

[NordicMan]

My WAAS is always enabled, but I doubt it does me much good so far "up north" (Ontario Canada).

 

I don't think it has any effect on battery life at all, and personally I don't know why someone would switch it off.. the only "penalty" for having it on is it will reserve 2 of your 12 satellite channels for the task, so that leaves only 10 for standard satellites.. or am I way off base?

[frozenflyboy]

My WAAS is always enabled, but I doubt it does me much good so far "up north" (Ontario Canada).

Makes no difference in Ontario. Canada has WAAS stations. WAAS ground stations simply tell the WAAS birds (satellites) if there are errors and so it sends out corrections

[+dfx]

always enabled and i do have a waas lock most of the time.

[+dfx]

the only "penalty" for having it on is it will reserve 2 of your 12 satellite channels for the task, so that leaves only 10 for standard satellites.. or am I way off base?

i'm not sure if a waas satellite uses up a "slot" at all. even if it does, the receiver is always only tracking one of them, and it's a very rare occurence that you're actually seeing 12 regular GPS sats. i've never seen more than 10 at a single time personally. plus, many modern GPS chips are actually 20-channel receivers now. so that's pretty much a non-issue.

 

supposedly it's possible that having waas enabled can have a negative effect when you're actually outside of the waas covered area, but manage to catch a waas signal anyway. so if you're outside of north america and europe, you may want to leave it disabled.

Edited August 26, 2010 by dfx

[+ecanderson]

always enabled and i do have a waas lock most of the time.

Ditto, now that the Dakota/Oregon firmware has the WAAS situation under control. Took them nearly forever to get to that point with STMicro, though.

 

Prior to WAAS working more than 1 in 10 times, my Dakota took seemingly forever to settle (relative to my experiences with the Summit and 60CSx models) and never did produce an EPE that was as satisfactory as I'd experienced with previous Garmin handhelds with WAAS working. I'm a much happier camper these days.

[NordicMan]

My WAAS is always enabled, but I doubt it does me much good so far "up north" (Ontario Canada).

Makes no difference in Ontario. Canada has WAAS stations. WAAS ground stations simply tell the WAAS birds (satellites) if there are errors and so it sends out corrections

Yeah but the "WAAS birds" are in geosynchronous orbit over the equator. From what I've read, the further away from the equator you are the less likely you will be to get a decent lock on them especially if you're a Geocacher, which by nature unfortunately means you're usually under tree cover, lol, so Canadians are at a bit of a disadvantage.

 

So if you check your WAAS status and don't see any positive result, you're basically "wasting channels" by dedicating them to look for these 2 specific satellites. My GPSr(s) are only 12 channel units, and yes I have seen all 12 being used. Despite all that I still leave WAAS enabled,, heck there's always hope

[+dfx]

Yeah but the "WAAS birds" are in geosynchronous orbit over the equator. From what I've read, the further away from the equator you are the less likely you will be to get a decent lock on them especially if you're a Geocacher, which by nature unfortunately means you're usually under tree cover, lol, so Canadians are at a bit of a disadvantage.

disadvantage yes, but even up here the sats are sufficiently high above the horizon (>20 degrees AFAICR) to get a good lock. after all, ontario is mostly flat! antenna quality will play a big role here though.

 

So if you check your WAAS status and don't see any positive result, you're basically "wasting channels" by dedicating them to look for these 2 specific satellites. My GPSr(s) are only 12 channel units, and yes I have seen all 12 being used. Despite all that I still leave WAAS enabled,, heck there's always hope

so, if you've seen all 12 channels used with WAAS enabled, doesn't that mean that enabling it actually doesn't "waste" those channels?

[frozenflyboy]

My WAAS is always enabled, but I doubt it does me much good so far "up north" (Ontario Canada).

Makes no difference in Ontario. Canada has WAAS stations. WAAS ground stations simply tell the WAAS birds (satellites) if there are errors and so it sends out corrections

Yeah but the "WAAS birds" are in geosynchronous orbit over the equator. From what I've read, the further away from the equator you are the less likely you will be to get a decent lock on them especially if you're a Geocacher, which by nature unfortunately means you're usually under tree cover, lol, so Canadians are at a bit of a disadvantage.

 

So if you check your WAAS status and don't see any positive result, you're basically "wasting channels" by dedicating them to look for these 2 specific satellites. My GPSr(s) are only 12 channel units, and yes I have seen all 12 being used. Despite all that I still leave WAAS enabled,, heck there's always hope

On my last trip to the US I had just as much difficulty with my GPS as I have in Canada. LOL Just makes a Canadian GCer cleverer.

[NordicMan]

so, if you've seen all 12 channels used with WAAS enabled, doesn't that mean that enabling it actually doesn't "waste" those channels?

Well I'm not sure. I assume you need a pretty decent lock on the WAAS sats in order to take advantage of them. If one of them does appear in the satellite listing but shows a really crappy signal, is it or isn't it wasting a channel?

[+dfx]

Well I'm not sure. I assume you need a pretty decent lock on the WAAS sats in order to take advantage of them. If one of them does appear in the satellite listing but shows a really crappy signal, is it or isn't it wasting a channel?

your GPSr should tell you whether it's using DGPS data or not. from my experience, the WAAS satellite only ever shows up in the list of tracked satellites if it's actually being tracked and the data used (and one sat only). but this is very likely different between manufacturers.

[+bcblues]

I've got a Garmin 62s with WAAS enabled. How do I know if I have a lock?

[+1Guy3gals]

I've got a Garmin 62s with WAAS enabled. How do I know if I have a lock?

First up make sure WAAS is enabled:

Main Menu>Setup>System>GPS - Change this box to WAAS/EGNOS

 

I cant seem to find where it indicates WAAS (I don't think it works in Australia anyway), but if your GPS accuracy is under 5m I would be guessing that you have achieved a WAAS lock. But if all else fails read the manual

http://www8.garmin.com/manuals/GPSMAP62_OwnersManual.pdf

[+dfx]

look at the GPS status screen, the one where it shows you the satellites and their signal levels. the signal bar for each satellite that gets augmented by WAAS will have a D in it.

[+bcblues]

Ah, for differential correction. I use hi end Trimble GPS units for work, and I am quite fluent in GPS (and GIS), but I was wondering about my new recreational GPSr. I just went out on my deck, and sure enough, all the sats had a D next to them! Thanks for the tip dfx. Must have missed that gem in the manual!

[+dfx]

Must have missed that gem in the manual!

manual? what manual?

 

somehow i have a feeling it's not even mentioned there.

[+EraSeek]

Here is an example of an Oregon400t sat status screen. 12 displayed channels and 1 WAAS slot. The WAAS is the one displayed to the far right (#48). The WAAS sat corrects the other GPS sats. Those that have the corrections applied have a "D" in the bar.

 

[frozenflyboy]

Here is an example of an Oregon400t sat status screen. 12 displayed channels and 1 WAAS slot. The WAAS is the one displayed to the far right (#48). The WAAS sat corrects the other GPS sats. Those that have the corrections applied have a "D" in the bar.

 

Thanks EraSeek,

 

Excellent explanation. What is the "d" short for?

How do you know that the slot 48 is the WAAS?

[+dfx]

Excellent explanation. What is the "d" short for?

D stands for "differential" in "DGPS".

How do you know that the slot 48 is the WAAS?

because there's only so many WAAS satellites up there. according to wikipedia, the currently active WAAS sats have NMEA numbers 46, 48 and 51. you'll only ever only see one of them in your list, and if you do you should start seeing the Ds popping up real soon.

[frozenflyboy]

Excellent explanation. What is the "d" short for?

D stands for "differential" in "DGPS".

How do you know that the slot 48 is the WAAS?

because there's only so many WAAS satellites up there. according to wikipedia, the currently active WAAS sats have NMEA numbers 46, 48 and 51. you'll only ever only see one of them in your list, and if you do you should start seeing the Ds popping up real soon.

 

Is the reason you'll only see one waas bird because of the distance between them and the curvature of the earth?

 

Wow I will be able to conduct a show and tell with the other pilots I fly with.

Only thing we pay attention to is the RAIM or Receiver Autonomous Integrity Monitoring. We need 5 sats I believe in order to do an approach. Not so much of an issue nowadays with more birds airborne. WAAS is required for very low approach limits.

 

Thanks much! Great education!

Edited August 30, 2010 by frozenflyboy

[+ecanderson]

because there's only so many WAAS satellites up there. according to wikipedia, the currently active WAAS sats have NMEA numbers 46, 48 and 51. you'll only ever only see one of them in your list, and if you do you should start seeing the Ds popping up real soon.

I'm looking forward to seeing 46 in operation since at 98 degrees it should be easy to see on this side of the continental divide when we start nudging up to the mountains on the Front Range while caching. Testing began in March and was originally expected to last until December '10, but somewhere I'd swear I had read that they were preparing to accelerate that based upon the problems with 48. Only 48 (for as long as it lasts) and 51 here so far.

[+ecanderson]

Is the reason you'll only see one waas bird because of the distance between them and the curvature of the earth?

Out in the "open" in the U.S., no. Both are visible (as will be 46). It's that your GPS only needs the info from one of them, so it locks on the first one from which it can get decent data.

 

As noted above, I'm on the E side of the Rockies. It's usually easier to spot 51 at 107 degrees (just a shade west, unfortunately) and 48 required a further distance from the mountains. Of course, since 48 is all over the place, I don't know where it is now. It was at 133 degrees, so it wasn't uncommon to get blocked out unless we backed away some miles from the moutains. 46 will be at 98 degrees, well clear of my big bumpy obstructions to the west.

[+EraSeek]

Yes, only one WAAS sat is required for your corrections. Monitoring stations gathers data about atmospheric signal delays and such, and send their data to a master station, which creates a model of the corrections for the entire WAAS area (north America) and sends this data to the WAAS sats which transmits that model to your GPS. Your GPS knows where it is and so applies the proper corrections for where you are.

 

Think of the correction model as a giant undulating nets that is spread across the continent. Where the treads of the net cross is the correction data for an area. Your gps looks for the closest thread crossing and applies those corrections.

 

Thus the accuracy of your corrections are not dependent on how close you are to a monitoring station. The modeling has solved that problem.

 

Here is what I am talking about as an example of what the model of corrections might look like:

Edited August 30, 2010 by EraSeek

[frozenflyboy]

Wow eraseek That is an excellent explanation.

 

Something I have always wondered about is why Canada has so few monitoring stations compared to the US? 6/42

[+dfx]

Thus the accuracy of your corrections are not dependent on how close you are to a monitoring station. The modeling has solved that problem.

how does that work? isn't the model just interpolating the amount of correction needed between the monitoring stations, and so the chance of inaccuracy gets higher the further away you are from any station?

 

Something I have always wondered about is why Canada has so few monitoring stations compared to the US? 6/42

probably because that ratio roughly corresponds to the ratio of the population numbers in those two countries

[+EraSeek]

Minimally. The nature of ionospheric errors and the power of computing, in my understanding, can fill in the blanks rather accurately. With Broadcast DGPS you are affected by distance from the monitoring broadcast station much more, although it is not huge when it comes down to it.

 

My guess is that they are newer to putting these together, and ionospheric errors are much less the further north you go.

Edited August 30, 2010 by EraSeek

[Now at Zero Gravity]

My 60C looks for 33 and 34, but not 46, 48, or 51. Never finds anything, of course. Any fix for this? Running latest software. Thanks!

[+dfx]

33 is EGNOS, dunno about 34. can you switch between WAAS and EGNOS?

[+ecanderson]

Thus the accuracy of your corrections are not dependent on how close you are to a monitoring station. The modeling has solved that problem.

how does that work? isn't the model just interpolating the amount of correction needed between the monitoring stations, and so the chance of inaccuracy gets higher the further away you are from any station?

 

Something I have always wondered about is why Canada has so few monitoring stations compared to the US? 6/42

probably because that ratio roughly corresponds to the ratio of the population numbers in those two countries

There are evidently very few discontinuities (see that great graphic, above) in the correction "map", so interpolation for any given set of coordinates is adequate to provide correction information below the threshold of the other causes for error. Once the correction is adequate to get your error well below the other sources (receiver clock, multipath, etc.) it doesn't contribute much to the cumulative result. Net result: close 'nuf.

 

As for Canada, WAAS was designed primarily for GPS assisted landings, and at higher latitudes, the signal (the satellites broadcasting the WAAS data are geostationary - hence equatorial) near ground level isn't all that great, especially out to the east. You'll note that we put the current set of birds up with a very western bias - partly to get us (U.S. us) better coverage in Alaska (won't get into the history of #35 and #47). While that helps a lot in western Canada, it doesn't do them much good out east in the upper latitudes. Not much reason to add ground stations there with the original configuration of satellites. When you get far enough north or east, the theoretical ability to "see" those satellites AGL isn't as good as reality. At a degree or two above the horizon, a few tall trees can block the view pretty easily.

 

When #46 comes online, two of the newer (2007) stations out in Gander and Goose Bay are going to become a whole lot more relevant. #48 never did cover that area, and it's kinda out on the fringe of decent coverage for #51. Placing this new bird 9 degrees east of #51 is going to make it nice for a lot of us. As I noted before, it certainly will make caching up near the front range of the Rocky Mountains a bit easier for some of us.

[+fizzymagic]

Thus the accuracy of your corrections are not dependent on how close you are to a monitoring station. The modeling has solved that problem.

how does that work? isn't the model just interpolating the amount of correction needed between the monitoring stations, and so the chance of inaccuracy gets higher the further away you are from any station?

 

No. The main correction is an ionospheric depth model; it is considerably more sophisticated than simple interpolation between points. Here is one explanation.

 

One particularly nice thing about WAAS is that the ionospheric model can be changed and improved with no changes in the receiver, since it is done by the network. In fact, the models may well have been improved over the last few years; I am not sufficiently expert to know whether or not they have.

 

As a result of the model, the WAAS correction is not pinned to the exact correction measured at a base station. Which is why, generally speaking, the accuracy of WAAS does not depend on your proximity to a base station.

 

The other WAAS corrections are not spatially dependent so it doesn't matter where you are.

[frozenflyboy]

I was in Iqualuit today (N 63.45.141 W 068 31.490) and I was not getting any WAAS birds on my Colorado 300.

I got satellites # 3 6 7 8 13 16 19 21 23 24 26 33. 24 was a bit low signal strength and 33 was in and out. By the runway area (Ramp) there was a clear area to the south and west and east.

 

The cache (a magnetic micro BTW 10 minute walk from the terminal that I had time to do was not difficult to find but the GPS was doing quite a bit of jumping around in an open area (no trees).

Edited August 30, 2010 by frozenflyboy

[+ecanderson]

I was in Iqualuit today (N 63.45.141 W 068 31.490) and I was not getting any WAAS birds on my Colorado 300.

Iqaluit (sp above) has one of the ground stations (of the 4 in Canada). Yeah, the signal strength up there is pretty sketchy - I'm sure that's one of the reasons they haven't installed new ground stations further north. When 46 comes on line, you should finally get a usable signal up there. 9 degrees east doesn't sound like much, but it should give you WAAS service you can use.

 

I should add that the "33" you saw was the westernmost of the European EGNOS satellites (somewhere just under W Africa). I'm surprised you were able to pull that one in at all. They've got a ground station for that one in Montreal, so I would imagine if you could lock up on 33 you might get some useful data up there.

Edited August 31, 2010 by ecanderson

[frozenflyboy]

Interesting. The GPS was making big jumps BTW as could be expected, but it did settle and wasn't bad at all.

[+PDOP's]

I was in Iqualuit today (N 63.45.141 W 068 31.490) and I was not getting any WAAS birds on my Colorado 300.

Calculated with Fizzycalc:

 

Iqaluit, Nunavut Territory (N63.7513 W68.5257)

 

WAAS 48 PRN 135 133.0°W Elevation: 2.3° Azimuth: 246.8°

WAAS 51 PRN 138 107.3°W Elevation: 11.7° Azimuth: 221.8°

 

Note that 48 is drifting east so would be a little higher in the sky. I believe it was at about 123.0°W in mid August.

[+fizzymagic]

I was in Iqualuit today (N 63.45.141 W 068 31.490) and I was not getting any WAAS birds on my Colorado 300.

Calculated with Fizzycalc:

 

Iqaluit, Nunavut Territory (N63.7513 W68.5257)

 

WAAS 48 PRN 135 133.0°W Elevation: 2.3° Azimuth: 246.8°

WAAS 51 PRN 138 107.3°W Elevation: 11.7° Azimuth: 221.8°

 

Note that 48 is drifting east so would be a little higher in the sky. I believe it was at about 123.0°W in mid August.

 

I should fix FizzyCalc to let you input the current location of the WAAS birds, shouldn't I?

[+PDOP's]

I should fix FizzyCalc to let you input the current location of the WAAS birds, shouldn't I?

That would be handy but remember that 48 will be gone shortly and 46 should be operational before the end of the year.

[+user13371]

I should fix FizzyCalc to let you input the current location of the WAAS birds, shouldn't I?

Or... you could have it pull all of the sats positions live from the web... http://www.nstb.tc.faa.gov/incoming/Waas_SV_Status.txt

[+fizzymagic]

I should fix FizzyCalc to let you input the current location of the WAAS birds, shouldn't I?

Or... you could have it pull all of the sats positions live from the web... http://www.nstb.tc.faa.gov/incoming/Waas_SV_Status.txt

 

Hmm... I haven't had FizzyCalc use networking to keep it simple, but I think I'll put out a new tool to locate the WAAS satellites. It'll give me a chance to try Python package deployment...

[Now at Zero Gravity]

33 is EGNOS, dunno about 34. can you switch between WAAS and EGNOS?

 

Nope. WAAS enabled or disabled is my only choice.

[+Rotareneg]

I believe some units have a fixed SBAS almanac while others can scan for SBAS SVs and update the almanac. My 60Cx and PN-40 seem to be in the first category as I never seem them scanning for other SVs if they don't have line-of-sight on 48 or 51, while my much older Legend does scan all potential SBAS SVs if it can't find 48 or 51.

Edited September 1, 2010 by Rotareneg

[xyzee]

Test on my 60Cx, for no WAAS, was shutdown at 19:47. WAAS on, 19:23. Same batteries, charger, charge time.

 

On the 60C, it starts looking fof 33 and 34 in the two slats, and works it's way up to 48 and 51. This can take the better part of 20 min, when out of the box, or after a hard reset, or maybe even if I haven't used it in a while, but it usually will go to 48 and 51 shortly, if not right away, when used daily. Exceptions are when there are 12 to 14 Sats in view, it will kick off 48, here in high desert Utah. For several days, in the spring of 07, the Sat line up was so good, that the 60Cx kicked off any WAAS Sats, and used all 12 regular Sats, just like Garmin said that they might, when their accuracy was better without WAAS. That was at the same time that I had a 60Cx along side of the 60C, when 51 was kicked off of the Cx, 48 was kicked off of the C.

Note: Back in the spring of 06, when 35 was being moved, and we couldn't get any WAAS Sats on our new "X" receivers, Garmin sent some of us emails stating that the engineers had found that WAAS had improved the SiRF chip reception, by only about 5 to 7 inches, so they planned to drop "WAAS" in a future version.

But the cuss and fuss continued, so they kept it, thank goodness, as 51 helped me with a better position fix in the high mtn valleys. When I enable WAAS, on the 60Cx SiRF, the "accuracy" usually goes from 7 ft to 8 ft, sometimes stays on 7 ft.

On the 60C, and on my favorite, the GPS 60, with WAAS disabled, usually they will read 13 ft "acccuracy", and drop to 5 ft (or 1 meter) after about 3.5 to 4 minutes, after WAAS is enabled. Have to let them stay out in the open, with a clear view of the WAAS Sats, so they can down load the 250 packets a second with all of the corrections, etc, for the better part of 5 min.

Also, one can get a ballpark idea of what the elevation is of 51, by looking at their, or a neighbors, Sat TV dish angle, as they all in the general area of 51.

[+Rotareneg]

i'm not sure if a waas satellite uses up a "slot" at all. even if it does, the receiver is always only tracking one of them, and it's a very rare occurence that you're actually seeing 12 regular GPS sats. i've never seen more than 10 at a single time personally. plus, many modern GPS chips are actually 20-channel receivers now. so that's pretty much a non-issue.

 

Just did a little experiment with my PN-40 this morning: there were 16 GPS satellites above the horizon (18 including the two WAAS ones,) but my PN-40 would only show 12 GPS SVs and one WAAS. It would occasionally swap different SVs in or out, but it never had more than 13 total.

[+PDOP's]

I should fix FizzyCalc to let you input the current location of the WAAS birds, shouldn't I?

Or... you could have it pull all of the sats positions live from the web... http://www.nstb.tc.faa.gov/incoming/Waas_SV_Status.txt

 

Hmm... I haven't had FizzyCalc use networking to keep it simple, but I think I'll put out a new tool to locate the WAAS satellites. It'll give me a chance to try Python package deployment...

Now that the WAAS satellite situation has settled down any chance for an update to FizzyCalc to handle the current location of the WAAS birds?

 

 

Image above represents the broadcast footprints of the geostationary satellites in December 2010.

[frozenflyboy]

I should fix FizzyCalc to let you input the current location of the WAAS birds, shouldn't I?

Or... you could have it pull all of the sats positions live from the web... http://www.nstb.tc.faa.gov/incoming/Waas_SV_Status.txt

 

Hmm... I haven't had FizzyCalc use networking to keep it simple, but I think I'll put out a new tool to locate the WAAS satellites. It'll give me a chance to try Python package deployment...

Now that the WAAS satellite situation has settled down any chance for an update to FizzyCalc to handle the current location of the WAAS birds?

 

 

Image above represents the broadcast footprints of the geostationary satellites in December 2010.

Season's Greetings,

That's neat, Thanks!