"RF transparent houses"

[+user13371]

Over in a different other forum, someone was commenting on how they can only an GPS fix inside their home if the GPS was near a window.

 

I live in a single story frame hosue, and most of the GPS models I own usually CAN get a decent fix inside, even in an inside hallway away from windows. I only have one that HAS to be outside or near a window to lock on.

 

Obviously the wood, plaster, and shingles of my home are fairly transparent in that RF range. Is there a good reference somewhere on attenuation of GPS signals through various types of building materials?

[+mattalbr]

http://www.epn-online.com/page/18358/high-...-requires-.html

Navigation inside buildings

 

"Indoor GPS" misleads some users who might expect a similarly high GPS performance as that perceived outdoors. In reality, the GPS receiver picks up very weak scatter signals, which have penetrated into the building through lightweight construction materials and windows. GPS signals entering through the window may have been reflected against objects near the building, for example an office building on the opposite side of the road. Processing GPS signals where most of them have been reflected at least once leads inevitably to lower positioning accuracy. For example, an indoor-capable GPS receiver located in a brick building may compute a position with accuracy of 100 meters or worse, which is due to exploiting the benefits of signal multi-path. Much better accuracy is achievable in buildings made of lightweight construction materials (wood, glass) where the GPS signals attenuated by these partially permeable materials propagate directly (without reflections) to the receiver. For example, an emergency call initiated from an indoor GPS-enabled mobile phone can save a life if at least an approximate position fix can be provided. However, accurate room-to-room navigation expected to work in any building using GPS is not yet a reality."

 

Doesn't answer your questions but it's leading me to read more about it. Would like to get journal article:

http://www.springerlink.com/content/bdjgbxkhfyud8eqb/

Edited March 19, 2009 by mattalbr

[Ken in Regina]

I have "low-E" windows in my house and the worst place to try to get a GPS signal is near a window. There seems to be some sort of coating in the windows that blocks the signal.

 

...ken...

[+W7WT]

My radio room which is also the family room and where I have my computer is almost RF shielded. It has two aluminum foil layers of insulation in the ceiling and walls. Even the new Nuvi 550 and the Vista HCx can only get a bar or two. In fact it is difficult to get a cell signal. In the front room that has large windows on the West looking at the Olympics most of my GPSs will get full bars with WAAS indicated.

 

In my Roadtrek Van type RV the top and much of the side is fiberglass and it is like being out in the open. When I got my very first GPS, the Garmin 45, I used a passive antenna to boost the signal and had it setting on a shelf near the top inside the van. Worked just as well as having it outside.

Edited March 19, 2009 by W7WT

[+Team CowboyPapa]

 

Obviously the wood, plaster, and shingles of my home are fairly transparent in that RF range. Is there a good reference somewhere on attenuation of GPS signals through various types of building materials?

Check these:

http://www.fas.org/irp/offdocs/dcid6-9.htm

http://www.adamoconstruction.com/

http://quietsolution.com/html/scif.html?gc...CFRwDagody2XiJA

 

Anything else with which I may help?

[+Hrethgir]

Don't forget that the electrical wiring in your house is throwing off a constant RF field that probably doesn't help. I've noticed that my Legend HCx can get a fix from the middle of the downstairs floor in my two-story apartment, but my DeLorme PN-40 needs to be around a window. And even though the HCx gets a fix, it's very poor accuracy, probably because it's picking up scatter coming in through the windows as much as signals sneaking though the building materials and electrical RF fields.