Thread: Attention Newbies! Everything (almost) you want to know about GPS (Part 1)

There are also CF type receivers that can plug into your PDA's Compact Flash slot, or your PC's PCMCIA slot with an adapter. CF is same as PCMCIA only smaller. I use one of those, it has an external waterproof antenna. One thing I noticed is that my PDA gets a lock much much faster than my PC. Maybe it's in the software, or something else. Either way, just letting people know.

couple notes about Delorme Street Atlas:

-the info in the GPS/Navigation pane (bottom of the screen) is large enough that at standard carpc resolutions it should be fairly easy to read.

-tts directions are somewhat understandable. but dont bother using anything other than Microsoft's default tts voices. i tried AT&T's natural voices and it ended up messing up some parts such as reading "st." simply as that rather than "Street"

-did pretty good as to reading off directions early based on your speed and distance from the next direction

a side note which may help guage my opinions here: i tested this on my home pc with a gps simulator with my own custom gps log that was created using MS S&T2k5's lon&lat finder. the reolsution during this test was 1152x870

Bump - This is good info, why isn't this stickied?

Are there any free GPS Navigation software progs?

All the various specs confuse me. WAAS and EGNOS and Sirf and xtrac and DGPS - I don't know what any of that stuff means or how it should affect my choice. 10-15-20 meters seems to be a standard accuracy. Is that really about as good as it gets? I had always thought GPS could get as close as just a couple of meters.

DGPS

DGPS stands for "Differential GPS" and refers to a method of referencing various ground station broadcasts to improve the accuracy of GPS signals. At one time, the commercially available GPS signal was "degraded" by the US military to reduce its accuracy to 5-10 meters. DGPS was a method to correct for that degradation. The degradation was turned of some years ago. DGPS operates similar to WAAS, below.

WAAS

WAAS stands for "Wide Area Augmentation System". A detailed explanation of WAAS can be found here: http://en.wikipedia.org/wiki/WAAS. The short version is that WAAS is a system of GROUND based GPS transmitters operated by the FAA that are intended to increase the accuracy of the GPS signal. It's primary purpose is to allow aircraft in a metropolitan area that are equipped with WAAS receivers to fly more accurate instrument approaches at airports with the proper WAAS approach procedures. WAAS provides 1-2 meter accuracy horizontally and 2-3 meter accuracy vertically.

LAAS

LAAS stands for "Local Area Augmentation System". Same idea as WAAS but installed at each airport. LAAS is even more accurate than WAAS and allows approaches to be flown in very bad weather conditions.

You don't need WAAS or LAAS. First, WAAS is expensive and unlikely to be installed anywhere but the major metropolitan areas. The FAA has no money and won't deploy it very quickly. By then, you'll own another receiver. Also, consider how accurate you really need to be. So what if you are 30 feet off on the map? First, how can you be sure the error comes from your GPS or perhaps because the map you are using is inaccurate? Second, even if you're 30 feet off, there are very few instances where this will get you lost.

Your best bet for accuracy is to receive as many satellites as possible. The more satellites, the better. Most members here report receiving 6 or more, but that can vary depending on time of day and weather conditions.

EGNOS

EGNOS stands for European Geostationary Navigation Overlay System. EGNOS supplements GPS, but probably only in Europe to begin with. It is similar to WAAS in it's functionality, adding accuracy to the signal (2 meters) and uses a combination of ground and geostationary satellites to achieve this. EGNOS is a precursor the the Gallileo positioning system, a European satellite based positioning system. EGNOS becomes operational in June 2005.

SiRF

SiRF refers to a chipset used in GPS receivers, much like Intel Pentium refers to a type of processor. SiRF chipsets are supposed be be pretty good (anyone with comments here?). An excellent explanation of the various SiRF chipsets is here: http://www.pocketgps.co.uk/xtracornoxtrac.php

SiRFXTrac

XTrac is a software firmware enhancement used in a variation of the SiRF chipset that provides increased performance over regular GPS units. It's main purpose is to tune in stronger satellites first, then work on aquiring weaker satellites that might be rejected by other GPS receivers. Bottom line - it makes your GPS more sensitive. It might make the time to first fix a bit slower, however.