I get a signal just fine in a 2-story brick and tile. Out of interest just tried it in my tin shed out the back. Yep got a signal. Accuracy not as good as inside the house but still got a signal that would give me a rough position within 20m. Me thinks some handhelds are better than othersOriginally Posted by SatNav
1. GPS users need to loose this notion that GPS works fine in buildings as they simply do not provide an acceptable order of service
2. This is a very misleading concept
Why loose it when it is true?
I have street maps installed on my GPS and when inside, it is showing me pretty much where I am at the current street location...
Of course there is little reason to be using a GPS indoors anyway really, but I don't see why we need to loose any notion at all when the evidence is right there staring you in the face? Have you used one of the better handhelds like the Garmin 76CSx? Mate it works indoors, in rain forests under heavy canopy, even in my tin shed (although not as well). It's a bloody good unit!
Note also that the 76CSx is WAAS compatible which further improves its accuracy and availability. WAAS is generally only available in the USA but according to some WAAS graphics, there is potential availability close to the eastern seaboard of Australia...
From wikipedia:
The WAAS specification requires it to provide a position accuracy of 7.6 meters or better (for both lateral and vertical measurements), at least 95% of the time. Actual performance measurements of system at specific locations have shown it typically provides better than 1.0 meters laterally and 1.5 meters vertically throughout most of the contiguous United States and large parts of Canada and Alaska.[2] With these results, WAAS is capable of achieving the required Category I precision approach accuracy of 16 m laterally and 4.0 m vertically.
http://en.wikipedia.org/wiki/Wide_Ar...ntation_System
Last edited by BaitThrower; 16-03-2008 at 10:10 AM.
1. If the evidence was there then they would have solved the mobile phone issues with 911/000 type calls a long time ago.
2. There is a good reason why this has not happenned but obviously some continue to not understand the issue behind not currently being able to use GPS for this purpose.
aren't we talking about GPS and internal/external antennas? All I'm saying is my internal antenna Garmin GPS works indoors, probably due to the fact that it may be working better using the WAAS as I mentioned above... and perhaps the SIRF technology it uses too?
The fact remains, my GPS works fine indoors and that is my reply to earlier posts. Obviously, not ALL GPS receivers do, so its an exception to the "rule", which obviously is not a solid one anyway
Last edited by BaitThrower; 16-03-2008 at 10:19 AM.
"Can you can add to that, inside a structure on land the aerial (internal or external) isn't moving about as the unit/aerial will often do when on the water."
1. The moving about bit is the key as heading in different directions will create a different set of circumstances depending on where the GPs is mounted
2. Satellites also move and at different times of the day satellite numbers can be quite low creating poor signal, reception and position quality
fair enough but I've never had any problem outdoors or using it on the boat so far. It has always retained a good fix with at least half a dozen satellites outdoors.
"All I'm saying is my internal antenna Garmin GPS works indoors, probably due to the fact that it may be working better using the WAAS as I mentioned above..."
1. The first thing you need to do is turn WAAS off as it simply does not work in Australia
2. Then how about you convince me your simplistic el cheapo patch type antenna can out perform some of the high end geodetic antenna's then I want to see the evidence not a perception
3. Not even high end antenna's work fine indoors
According to this CASA article, Australia can get U.S. WAAS signals from the INMARSAT Pacific satellite?
http://www.casa.gov.au/fsa/2005/aug/54-55.pdf
I'm not saying this internal antenna can outperform high end antennas. But if it works inside, and they don,t well maybe it can, reception wise at least. The fact is that here I am sitting inside, moving or not moving and I am still getting a fairly accurate fix on my location, well within 20m I would say according to my map. Do I need to take a photo to prove it??
I remember the episode where the Goodies (some young blokes will not know who I am talking about) were driving their house down the highway, possibly an application for this GPS
My Garmin 12 works also indoors too, of coarse until my indoors move consistantly I will have no need to fit an external aerial.
My Garmin 12 can make tracks well enough to overlay on a map from under the car seat!!
Some seem to recieve far better than others I have used, at least in my experience.
cheers fnq
1. POR (inmar3f3) no longer carries a WAAS signal
2. The nearest WAAS satellite now is AOR-W which even from the east coast is quite low on the horizon
3. There is not and never have been any ground station in Australia for WAAS to determine corrections from.
4. Enabling WAAS in Australia will generally degrade accuracy not improve it.
5. AirServices Australia have developed what is in fact a much better and cheaper solution to WAAS due to the fact that WAAS does not work in Australia
6. AirServices have called their system GRAS and currently even selling the technology back into the US where WAAS doesn't actually work to spec either
Last edited by SatNav; 16-03-2008 at 11:09 AM.
Ok, WAAS or no WAAS, it still work indoors for me
1. Disabling WAAS won't change the GPS signal but will most likely change the accuracy for the better.
2. Now you might actally be in real world coordinates?
3. Wonder how many other GPS users outside of the US have WAAS enabled and Why?
Will have to check my chart plotter just in case!
cheers fnq
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