Talk:Wide Area Augmentation System

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[edit] Complete Article Update

I've spent the last month working an improved version of the article in my personal sandbox. I believe it is suitable for posting into the main article at this point, with the group helping to make the final improvements. The article is not perfect (history still needs to be re-written, and the drawbacks are still in list form, etc.) but I feel it is best for the group to improved after my personal fork is re-integrated.

Since its a complete change it seems some discussion is appropriate first, so I'm posting notice here and asking those interested to review the copy in my sandbox and comment here. Here is the sandboxed article: User:Davandron/WAAS

Thank you everyone in advance for the constructive feedback and guideance! Davandron | Talk 17:27, 29 November 2006 (UTC)

The main article has been updated. Davandron | Talk 14:35, 5 December 2006 (UTC)

[edit] Identical content?

The first few paragraphs contain sentences verbatim from http://gps.faa.gov/Programs/WAAS/waas.htm; is that kosher? --R27182818 05:39, 26 September 2006 (UTC)

US Government websites are public domain. --Dual Freq 11:33, 26 September 2006 (UTC)

[edit] Merge

I suggest someone merge GPS_WAAS into this article. Ideas? --Dual Freq 01:11, 9 May 2006 (UTC)

Strong yes. They do seem redundant... -- RevRagnarok 02:24, 23 May 2006 (UTC)
Strong yes, provided that only the redundant information in GPS_WAAS is removed, and the remaining non-redundant information be remain, and the article be expanded to include key info on non-GPS WAAS systems, such as those coming online here in Europe. Dr1819 18:30, 10 June 2006 (UTC)

[edit] This article is about WAAS

In this revision, I pulled a large section out of the History/approaches section. Most of it was a bit tangent to the subject of WAAS, maybe it could be distilled to something smaller and more readable. I think this article should focus on the capabilities, limitations, history, operation and future of WAAS. Comparison of WAAS with other systems is probably acceptable as long as it's very concise and doesn't stray from the subject WAAS. We don't need to explain GPS, ILS, MLS and every other radio navigation system in this article. I suppose consumer usage of WAAS could be mentioned, but WAAS was made for aviation usage, so that should be the focus of this article. --Dual Freq 23:44, 12 June 2006 (UTC)

And if we are to re-add that section, I would suggest finding some references and cite it appropriately. --Dual Freq 23:47, 12 June 2006 (UTC)
Dual, you have now cut background information from this article twice. Both times your comment is simply that the content in question was "off topic". However, the resulting article is now far too on topic to be readable. Do you see what I mean by this? It may not be clear.
Remember, the wiki is an encyclopedia, not an aviation navigation primer. The average user coming to this page will known little or nothing about existing navigation systems. Providing this information and comparing it with similar, or older, systems allows the reader to put WAAS into it's proper context. Without this information the reader will build a false image of where WAAS fits into the navigation "world" (ie, in isolation).
The pre-cut article was just over three pages long. Three pages is not too long for a topic like this. If you add up all the background information that you removed, it only added about 1/2 of a page in total. This doesn't strike me as too much either, 1/2 a page for context seems like a very small price to pay.
I really don't see the argument for this content's removal. Maury 12:28, 13 June 2006 (UTC)
I agree that a little too much might have been taken out here, but I will try to revisit later - a lot new was also written, not just moved. -- RevRagnarok Talk Contrib Reverts 13:31, 13 June 2006 (UTC)

I may have pulled a bit much, but my initial thought remains the same. Each navaid has its own article, in fact there is an article specifically for Radio navigation. Do we need to add a history of radio navigation to every article about radio navigation systems? There was even a section in here about MLS, a system I think was killed by GPS, not really by WAAS. Additionally, there was a swipe in there about ILS providing "a rough fix". That's not correct, WAAS has only just recently, after much debate, been declared "equal" to ILS Cat I, but it can not and will not equal Cat II or III ILS systems. If I remember correctly, the FAA actually lowered the standards for Cat I to allow WAAS to replace it. (I'll look for a ref for that bit of info before adding it to the article though.) In summary, I'd suggest carefully examining what was removed, citing it and re-adding it, if it's that important to the continuity of the article. As for the LAAS link at bottom, I pulled it because it was mentioned in the article and in the GPS template at the bottom. --Dual Freq 23:02, 13 June 2006 (UTC)

[edit] Lead paragraph

I'll separately address the lead paragraph, which I deliberately removed it once, but I must have removed it along with the rest when I made the above revision. Comparison with similar systems might be OK, but is it really lead section material? I also dislike the content, compare with this and I'll explain why I removed it, point by point. DGPS is only similar to WAAS in that it corrects errors in GPS. The methodology is totally different, WAAS uses a grid covering the entire world and provides corrections for grid sections covered by its reference stations, calculating the error using data from all ref stations and using software/algorithms to approximate the error in other areas not next to a ref station. DGPS (the USCG version at least) each station is independent, transmitting corrections only for satellites within view of that one station. It's run by the USCG not broadcast from "commercial radio stations", but I may be misunderstanding the meaning of commerical radio stations. I understand that to mean Commercial broadcasting radio station, which doesn't make sense to me since the largest (I believe) DGPS system (in the US) is free, run by the USCG. USCG DGPS was primarily for ground usage, such as trucks, boats and trains, I don't think it was ever used/considered for aviation usage. USCG DGPS uses LF which covers a large area, ~200 miles from the site and does not require line of site to the transmitter. LAAS doesn't deliberately limit its coverage to the airport, but it is limited to a small area because of the VHF line-of-sight radio link it uses. Its correction would likely be just as useful as USCG DGPS in that it would degrade in accuracy the further from the airport you were. LAAS would be useless to consumers because of the VHF link used, but DGPS is useful because of the low freq used. Additionally, is LAAS/GPS used for takeoffs? I'm not a pilot, but are there instrument takeoff procedures like the instrument landing procedures? Maybe a section titled, "other GPS correction systems" or similar could address alternative systems, but the see also section and wiki-links already point to GPS and alternatives like LAAS and DGPS. Citations would be nice as well. --Dual Freq 23:02, 13 June 2006 (UTC)

Hi, Dual Freq. I am a pilot, with just over 2,300 hours in military aviation. You hit the nail on the head - WAAS was developed primarily with aviation in mind, but since Department of Transportation funding was involved, I'm sure they were considering more precise navigation for tricky intersections like like multiple-entrance/exit cloverleafs, and heavy fog harbor navigation. WAAS is the medium-accuracy alternative to Cat I ILS approaches, primarily for smaller airfields which cannot afford the expensive initial cost and maintenance of precision and non-precision navigation facilities. LAAS is the high-accuracy alternative to CAT II and CAT III ILS approaches. The most precise CAT-III equipment allows pilots to take-off and land in 0-0 vis situations. Dr1819 23:29, 13 June 2006 (UTC)

By the way, I re-added the link to the [Joint Precision Approach and Landing System] article in the See Also section, as literally hundreds of thousands of civilian contractors, and many times that many members of the military, will soon be riding aboard military airlifters and certain contracted civilian airlift aircraft. These systems will soon be deployed to many critical locations throughout the world, not just in combat zones. It's an amazing system with very close ties to WAAS, but some possessing important key elements, some of which may eventually find their way into civilian systems to deter unauthorize signal alteration. Dr1819 23:29, 13 June 2006 (UTC)

I just realized I broke my own unstated rule, and edited before checking for changes here. Bad Maury, bad! *rubs nose on keyboard*
Anyway...
- DGPS is only similar to WAAS in that it corrects errors in GPS.
Isn't that the point though? That's certainly why I mentioned it. My concern is that if someone were to arrive here from google (which is likely how they'll get here) and read the article as it was, one would be left with the impression that WAAS was the only such system. This is very bad.
I think the average reader will find DGPS, WAAS and LAAS very much comparable based on the fact that they all correct the GPS signal by comparing the measured signal with a known location. The only difference is how they distribute the signal. In fact, John Deere refers to their StarFire sat-based system as a "wide-area Differental GPS system". Perhaps I'm misunderstanding your line of reasoning, but it would seem that following your comments above, one should not mention PAL in an article about NTSC.
  • Response - isn't that akin to leaving out "blood" in an article about the heart? I believe terms need context for enhanced comprehension. In WAAS, it needs to be mentioned that it piggybacks on GPS, augmenting the signal with corrections to increase accuracy. LAAS should be mentioned as "an even more precise system," but little more. Hopefully, we can clean up the Precision Approaches section in a way that correctly puts all of them into context, perhaps a GPS-based Precision Approaches subsection. Dr1819 20:13, 15 June 2006 (UTC)
I think it's even more important to mention ILS and MLS. Not only is the way GPS "came out of nowhere" and bushwacked 20 years of MLS development interesting, it also provides valuable background on why replacing ILS with WAAS is both interesting and something to be approached carefully.
  • Response - Approaches are broken up as follows:
Visual Approaches
(etc.)
Instrument Approaches
Non-precision approaches (courseline and distance, but no glidepath)
Precision Approaches (courseline, distance, and glidepath)
ILS
MLS
GPS-based Approaches
Medium Accuracy
WAAS
High Accuracy
LAAS
JPALS
All three GPS-based approaches use DGPS as a technology. How it's used varies. Dr1819 20:24, 15 June 2006 (UTC)
- It's run by the USCG not broadcast from "commercial radio stations"
True today, but when the system was originally being set up they were going to use commercial AM and FM stations. These plans changed (in NA) when everyone started looking at WAAS. I should also point out that DGPS systems in other countries do use commercial radio. In Australia, for instance, it's sent out along with RDSinformation.[1]
- I don't think it was ever used/considered for aviation usage
Well I only learned about DGPS via aviation magazines I read while going for my IFR. All the GPS receivers I was looking at had DGPS inputs, specifically for this role. Yes, even the aviation ones. Most still do. Try googling "dgps aviation" and you get lots of real hits.
- Maybe a section titled, "other GPS correction systems"
Well this is certainly another way to attack the problem, and one well worth considering, but is a single paragraph in the intro section really too much? Considering the intro also points out similar systems in other countries, I really don't see this as too much of a stretch.
Now the History section is another matter entirely. It actually duplicates the comments in the intro section, so I can see an argument for removing one or the other. But to remove the history portion entirely strikes me as another very bad idea -- WAAS is the latest in a series of attempted upgrades to ILS, and talking about WAAS alone leads to that myopia again.
Maury 12:42, 14 June 2006 (UTC)

Good points for the DGPS article. Most of those DGPS Aviation real hits are about WAAS or LAAS which are DGPS, but not USCG DGPS which is what I thought we were talking about. How many DGPS systems have 6 second response time for out of tolerance conditions. I'm not sure I'd want the pilot to announce that the plane was landing using the John Deere Landing System. --Dual Freq 22:32, 14 June 2006 (UTC)

[edit] Verifiability

Generally, it is wise to add a citation or two when adding 6 paragraphs of content. Also, I think you've left out Omega, LORAN, GEE and that one with the morse code "A" and "N". And what about Canada Wide-Area DGPS (CDGPS)?[2] Don't want to leave that one out. Good job with the GPS article too, no need for references on the technical information there either, I'm sure we can trust you. --Dual Freq 22:32, 14 June 2006 (UTC)

Come now Dual, save this sort of banter for the Usenet. If you have actual complaints about the accuracy of anything I have posted, please feel free to be specific about those points. Given that all six paragraphs refer to other fully qualified articles on the wiki, your call for references is already answered. Look, I'm sorry I disagree with you about what information the article should contain, but you have yet to post a single cogent argument for the removal of this information. I asked, nicely, whether or not you felt this information would better be isolated into a separate section, and instead you responded with these two off-topic comments that could only be described as insults. I can't imagine how it is you feel this supports your case. Maury 14:29, 15 June 2006 (UTC)

I'll let you know when it's an insult. I responded with sarcasm because you already re-added the material in question. I still disagree with 5 paragraphs of radio navigation background for the reasons stated above, I can see comparison to the international standard of ILS or the VOR enroute functions that WAAS may eventually replace. MLS is a bit of a tangent, but who the hell am I. Usenet doesn't have a policy of WP:Verifiability, you can put whatever you want in Usenet. Here it is official policy to provide source material so that a third party can verify compliance with copyright and factuality. This article can get away with unsourced numbers and history because it is not a Good Article or Featured Article. If it is ever peer-reviewed, the first thing they will ask for is sources. The second will be WP:MOSNUM for all the numbers used elsewhere, but those are easy to fix. The sources are another matter, if someone ever does try a peer review, they will have to track down all the unsourced material and cite sources. It's easier to cite as you go, but what do I know. Carry on, forget I ever mentioned it. --Dual Freq 23:32, 15 June 2006 (UTC)

I agree that the article should focus on WAAS, and only briefly mention other technologies, but only if those are highly relevant to current WAAS operations. "WAAS is a form of differential GPS (DGPS)" is all that needs to be said about differential GPS. Similarly, a brief mention is in order about how WAAS is augmenting other instrument approach procedures at airfields with IAPs, but is expanding instrument approaches into airfields without other IAPs. We should leave the laundry list of IAPs to the [Instrument approach] entry. Dr1819 22:53, 29 June 2006 (UTC)

[edit] Updates and proposed changes

I made some significant updates to content and readability. I left 99.9% of the content in, but change some of the wording so as to be more precise. I would like to propose some significant reductions, namely in the content that's more appropriate elsewhere. While readers of this article do need to know that WAAS will eventually replace Category I ILS approaches, the information/criteria of Cat I, II, and III ILS approaches should not be repeated here, but should be referenced/linked to the ILS page which discusses the approaches in detail. There are several similar, and I believe unnecessary redundancies which also need to be deleted from here, but perhaps incorporated (if that's not already happened) on the appropriate pages.

What say you folks? Dr1819 19:36, 30 June 2006 (UTC)

I wouldn't be so optimistic about the "good news" of LAAS in Cat II/III situations. I expect ILS will be around for quite a while for those categories. LAAS is OK for CAT I, but I've heard "back to the drawing board" used to describe the state of II/III LAAS. There is some that doubt LAAS will ever meet CAT III. WAAS will never be CAT III either. Therefore, ILS will be around at least until the new multiple frequency GPS sats and receivers are out. I think the USCG DGPS system is still the primary differential system for rail[3] and waterways. It seems to work better for ground / water usage. --Dual Freq 21:42, 30 June 2006 (UTC)

Noted. Any opinions on the "significant reductions to content" issue and moving the material to where it's most relevant?

OwenX - some great edits on your part! Only two technical details which I'll take care of in the next few days. Nice work! Dr1819 22:06, 4 July 2006 (UTC)

[edit] Drawbacks and Limitations

There are now more than one certified receiver. Here is the yahoo copy of garmin's press release for their model series that are certified. link. Also, in some searching I've found other companies that have certified waas equipment.

I changed the article to say "limited number" of certified receiver models. If anyone has more info, please update that area. Davandron | Talk 19:44, 10 November 2006 (UTC)

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