GPSnewbie

In researching my first purchase of a GPS, how important is having WAAS?

dav

Having a Sirf chipset is better.

But if you get an older unit, and WAAS is available in your area, then it is a noticeable improvement over not having it.

GPSnewbie

Hi dav,

Thanks for the information. I talked to Garmin on the phone today and asked about Sirf since I couldn't find if the nuvis I'm considering have it. I was told that Sirf is a brand name and Garmin had their own "high sensitivity receiver."

Does this sound correct or was I talking to someone at Garmin that may have accidentally given me incorrect information?

In referring to what you said, since there are only approximately 25 WAAS gound reference stations across the U.S., if I'm not located near one of them, the WAAS on the GPS won't make my GPS more accurate. Am I correct in saying this?

I really do appreciate any help.

Max

Interesting...I've noticed they stopped using the "sirf" trademark lately myself. Their 'high sensitivity receiver' performs just as well as sirf if not better.

WAAS is not so important as making sure the unit has a high sensitivity receiver if you're after constant accuracy.


WAAS would not be a dealbreaker for me.

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GPSnewbie

Max,

I appreciate your response and information. Before getting notice you had posted, I asked another question strictly about SiRF. When/if you see it, know it was before I'd gotten notice about this post.

Thanks for all your help!

gpsnetwerx

the sirf chipset is basically a third party provider. it is like a motorola chip in an lg cell phone. sometimes it is easier to use a chipset that is built by someone else as opposed to in house development.

in and of itself, "sirf" and waas are independent of each other. the sirf chip includes waas. waas is a space based augmentation (differential) system. it allows for a "correction" to the measured/calced positions. without a differential correction, your handheld has a +/- 50 foot solution. waas uses 25 reference stations to model error sources and generate a corrector. given the distances of the reference stations to each other, the modeling provides an "advertised" solution to +/- 10-12 feet.

i run a reference station network where our spacing is approximately 60 miles. combined with dual frequency gps we are running at +/- 6mm horizontal in real time.

the importance of waas or any other augmentation depends on what you want in terms of accuracy and precision. waas is ideal of navigation but not for high precision work. on the other hand i wouldn't use a dual freq sensor to get me to the nearest poi. its all about what you use it for.

hopefully this was not too redundant or bored you out of your skull.

cheers
scot

GPSnewbie

Hi scot,

Thank you for your post! I wasn't bored and what you said wasn't redundant to me. I'm new to this. Anything you tell me is of interest and I learn from it.

I'm going to use the GPS for car directions. I have 'no sense of direction' and I'm new to this area. In the whole scheme of life, if I pass a turn it wouldn't be that critical... just very irritating and time consuming to be told after I'd passed it, I needed to turn around and back track. I guess after re-reading this, it really is important for the GPS to be precise. That's the reason, I'm wanting to buy one in order to get to where I want to go without problems, e.i. having to turn around. etc. I know I don't want/need one with bluetooth or FM transmitter.

Perhaps the best thing for me, is just take my time and get to know the tri-cities little by little. I don't travel out of town that often.

Thanks again for taking the time to share what you know with me.

gpsnetwerx

most of the new waas enable gps are very good. i just tested a new nuvi yesterday and liked the level of turn by turn instruction. the 260w gives voice instructions well in advance of the turn. play with yours and get the feel of it. it will do its job for you.

Max

damn, I definitely do not have any experience running a reference network....this is gonna be cool

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rapriebe

Basically WAAS is unnecessary overkill for a vehicle navigation GPS. Since the unit is designed so that the your location icon "snaps" to the nearest road, the extra accuracy that you are supposed to get with WAAS is defeated by this snap function. WAAS only improves accuracy by about 15-20 feet, and uses about twice the battery power of a non-WAAS GPS for that small gain.

If you were going to be using a handheld GPS for geo-caching, then the added accuracy might be important to you, but not on a unit that is going to be primarily used for street navigation.

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Rick