waas capable?

We've talked about it a lot...

Turning it on may give you some better accuracy, but, it will also drain your battery faster if not plugged in to an external power source.

See previous discussion:

Use WAAS or not? http://www.poi-factory.com/node/5698

WAAS - Why not? http://www.poi-factory.com/node/6864

Seems editing a post makes it move to the bottom of a thread...this was once above the comment than now appears directly above this one. Interesting quirk...

kch50428 interesting note about battery life; I hadn't paid attention.

dellecma Go to http://www.garmin.com/aboutGPS/waas.html to read more and here is a clip...

But the best info I find is on Wikipedia at http://en.wikipedia.org/wiki/Wide_Area_Augmentation_System

Would have ben nice if they had included it on the Nuvi 750.

I talked to a Garmin Tec last week who explained the WAAS indeed required more power. However, he also recommended that if your unit allows you to select it and you are pluged into the vehicle lighter, then indeed use it as it does provide better performance. Because mine is mostly always pluged in, I leave it set to WAAS.

Indeed, there were hot debates about WAAS' usefulness... and the general perception is that it creates more harm than good for the average user:

- faster internal battery drain;
- slighty longer time to lock onto satellites (FTL);
- slighty lower overall accuracy (!!!), definitely NOT improving it;
- WAAS' primary scope is to provide information about the altitude... do cars need this?

I'm keeping it disabled on my nuvi's... but hey, that's me.

Thanks for all the info. I will keep it on for now and chime back in with how it performs for me.

I re-read the original posts referred to above along with this one and decided to see for myself whether there was any substantial difference using WAAS. So today as I drove around Phoenix in partly cloudy to clear skies, I drove one way with WAAS, one way without (running several different errands). In both cases I got as accurate as 9 feet driving both expressway and city streets - I couldn't tell any difference in the accuracy. I'm sure if I had a way to plot how often and how long the accuracy remained high in each setting I could possibly discern a difference. But with just my personal observation (in this city with this weather condition), they pretty much looked the same to me.

It was my understanding that WAAS would improve accuracy the most where you get errors from tall buildings and hills etc creating multipath errors.
I am currently borrowing a friends garmin 680 which has it. Were there a lot of tall buildings where you did your test? 2 different garmin reps gave me 2 different answers on wether th3 700 series had it or not. I could not get to the satellite screen by tapping the top left of the screen on a 750 in the store so I could not get the no of feet accuracy to compare with the 680. The 680 said from 12-24 ft accuracy in my area.

No tall buildings to speak of. Those are really only in the downtown (Phoenix) area and I wasn't near there. I'll have to try that next time I'm there.

Nope!
The WAAS emitting stations are sitting on the ground in very, very seldom spots; these are not satellite signals and most of the time the gpsr is not even getting those but endlessly looking for (if WAAS enabled), so the whole positioning process is slowing down thus less (sometime) accuracy...
Anyway, the received WAAS signals do travel horizontally, parallel to the ground, meaning the tall building actually are a very efective shield against.

Not to sure that is correct. Please take a look at http://en.wikipedia.org/wiki/WAAS.

"... This is achieved via a network of ground stations located throughout North America which monitor and measure the GPS signal. Measurements from the reference stations are routed to master stations, which generate and send the correction messages to geostationary satellites. Those satellites broadcast the correction messages back to Earth, where WAAS-enabled GPS receivers apply the corrections while computing their position.
..."

The corrected differential message is broadcast through one of two geostationary satellites.

The article contains some very good information about WAAS.

Also see Gramin's site: http://www8.garmin.com/aboutGPS/waas.html

I'm neither disputing the ideal, theoretical side, nor starting another debate about! my statements are based on practical life experiences, posted by many users in too many forums... so anyone can take it from here, with the appropriate grain of salt.

I've had it set to WAAS since I own it and it works fine...Not one problem yet, so I just leave it set that way.

Waas is about as useful as POP is to radar detectors.

OK, I'll bite. What's POP?

POP is a new way of shooting radar that radar detectors can't detect unless they have pop detecting ability (even so it doesn't work well) POP shoots so fast that the detector can't read it. Very few departments use it and even when they do, it is hard to detect, so might as well not even have it enabled on the detector. With it enabled, some say that it slows down the detection rate.

I guess my point was, is that waas isn't going to give you much better (if any) accuracy, and it kills the battery.

Actually WAAS could be useful on a handheld unit when involved in an activity like geocaching, Most here are using their unit for vehicle travel and since virtually all of the units "snap to road" it makes very little difference.

Actually the better accuracy you may have picked up while looking for a geocache would be negated by the fact that the person who posted the coords didn't have WAAS enabled and was less accurate, I generally found it wasn't worth the battery drain on a handheld, and was negated by snap to road on vehicle units, so overall not much benefit.

I have 3 GPS units. 2 are WAAS capable, and I definately notice a slight difference in readings between the WAAS units and the non-WAAS units.

For what its worth, marine navigation used to use differential GPS, and the newer units are coming equipped with WAAS. Finding a repeatable point on the ocean is important for fishing, and scuba diving. The WAAS units definately help that accuracy and repeatability.

Gps magazine had a very thorough review on the 660. The author stated that the new serf III chip is so powerful that it exceeds the waas capabilities making waas unnecessary. Most of the newer model units utilize the serf III chip.

Remember, many GPS units update the display every second. When traveling at 60 MPH, you travel 88 feet in this second. That means the display is off by at least 88 feet at the instant just prior to the display update. The additional accuracy of WAAS (the jury is still out whether there is any) in a vehicle is insignificant when adding in the 88 feet display error.

RT

The "update" argument makes sense if you are considering movement in a forward direction, but what about when you've made a wrong turn onto a parallel road?

I know my nuvi 660 sometimes gets "confused" with interconnecting on/off ramps that are close together. It eventually figures out where it is once its obvious that I'm on a specific road.

This is what I was told by Garmin:

I have never seen a WAAS sattelite come up on the screen. It's always there on my 60CSx (even if I am unable to connect to it).

Different sites have found worse accuracy with WAAS on. Other than my post at http://www.poi-factory.com/node/5698,
I have only seen statements like "accuracy is better with WAAS on" ... no real-time numbers. Like I posted in that thread, I don't know if it's typical, but the real-time numbers I got showed no benefit of WAAS that over-ruled its disadvantages. Let's see some more real-time numbers so we can make an educated decision.

RT

I can only go by what I was told by Garmin, although I see from a little searching that others have been told different answers. Since the satellite screen on the 750 isn't even an official feature who knows what to believe. It is rather convenient that there's no way to turn it on or off in order to see if it's really there.

I'm pretty sure I saw somewhere on their website that it isn't, but I can't find it now.

Hmmm, I see several sale/review websites that say that it does, but I don't know how that happens when it doesn't ever see the waas sattelites (unless it's masking it)

At high speeds, the only benefit WAAS provides is in elevation accuracy. At least that is why WAAS was such a big deal with aviation GPSr units.

In comparing my GPS-V (WAAS) to Marine Units (WAAS and DGPS), and my GPS-12 (non-WAAS). The WAAS numbers were always repeatable to a much smaller degree of error than the non-WAAS unit. Of course this is my experience, and I can't claim that this is the gold standard.

I'm wondering if WAAS really made a big difference in the times of Selective Availability (SA) in which the satellites sometimes offered loose data to decrease the accuracy of GPSr units. There had been concern that these (military) GPS satellites would be used against us, thus the SA algorithm. Now that SA is turned off, does this limit the benefits of WAAS?

Am I on the right track here, since I offer supposition and not actual facts?

I trust the "reviews" here by real users then from a mag or website, esp after reading somewhere (someone on this site referred us to the article) that bluetooth was used for updating the GPSr.