The Real Info on WAAS

[+Klemmer]

If you would like to read about the real and correct information about WAAS, and how it works in the environment it was intended for (aviation), here is a link to a very good article in Inside GNSS. There is soooo much mis-information (or half-truths) tossed around in this forum, that I caution readers about it. I have almost stopped trying to correct it or add to it, as it would be almost a full-time job. The first half or so of the article is reasonably non-technical. Note that there is a link near the top of the article to download the whole pdf. There is more to it than what it on-line.

 

If you find it too technical and still have some interest in the subject, here is a link to a thread in the Benchmark Hunting forum, where there are some links to less technical articles over in Caching Now.

 

Moderator: Any interest in making this a sticky (pinned) thread? Might help newbies with WAAS questions..... or at least add it to the FAQ's.. ?

[+EraSeek]

Here is another brief summary: http://www8.garmin.com/aboutGPS/waas.html

 

Personally I view the forums as a learning place. Statements need to be challenged. It is how we, as non-professionals in the field learn the facts.

 

Your concerns in your article about hold-over corrections from the day before are probably not correct. Garmin, at least, only holds WAAS corrections for 2 mins after losing the WAAS sats as I recall. Magellen holds them longer. The newer units (60cx) will drop WAAS when not usable all together. A more likely scenario with your older legend would perhaps be when not able to get correction data no data was being applied, not even the pre-programed base corrections (just a theory) and thus your positioning was worse. At times with my old unit I would notice that I would do better with WAAS off when I could not recieve it as well. My position would be more stable. Not a problem with my 60cx as far as I can tell. Either way when I can get WAAS my position appears more stable and accurate.

[+Klemmer]

EraSeek:

Yes, learning is definitely important. Probably the main reason I continue to scan this particular fourm, at least most of the the time. Entertainment at times might be it, also!

 

My old GPSr that was giving me WAAS problems was a Magellan Meridian, which at the time was getting good WAAS (usually). This was from the older WAAS satellite pair, one visible in lower elevation from SoCal than the newer one(s) now, but it was still normally usable. Who knows what the Magellan firmware was doing? Sure bugged me at the time! Couldn't duplicate the "problem" a year or so later with other GPSr's. Now that Magellan GPSr is WAAS-less anyway, due to Magellan's very poor firmware design & total lack of customer support. Oh well.