[Geowanking] So do we entirely believe this?

Landon Blake lblake at ksninc.com
Mon Sep 24 13:01:15 PDT 2007


Chris wrote: "The problem with "tower's on the Earth's surface, that broadcast similar signals" is the choice of frequency.  One can use high frequency (like GPS) but then you can't penetrate anything.  If you go to lower frequencies you bounce and refract everywhere and the antenna phase centers wander all over the place, limiting accuracy (phase-range measurements are also much less precise).  Years ago I decided this wouldn't work with precision, but the Rosum guys seem to know something I don't (then again, I dont know their real precision either). "

Thanks for that explanation Chris. I now that "the devil is in the details". I don't know much about how Radio Signals work, but I've got a book on the subject that I hope to read one day.

Landon

________________________________________
From: geowanking-bounces at lists.burri.to [mailto:geowanking-bounces at lists.burri.to] On Behalf Of christopher.wilson at daimlerchrysler.com
Sent: Thursday, September 20, 2007 5:04 PM
To: geowanking at lists.burri.to
Subject: RE: [Geowanking] So do we entirely believe this?


Landon- 

The problem with "tower's on the Earth's surface, that broadcast similar signals" is the choice of frequency.  One can use high frequency (like GPS) but then you can't penetrate anything.  If you go to lower frequencies you bounce and refract everywhere and the antenna phase centers wander all over the place, limiting accuracy (phase-range measurements are also much less precise).  Years ago I decided this wouldn't work with precision, but the Rosum guys seem to know something I don't (then again, I dont know their real precision either).   

In two weeks some details of the thinking on the national PNT (Position, Navigation, Timing) architecture should be coming out.  Some rumors have it they will advocate (among other things) a common clock and reference frame encoded on all broadcast signals, and compatibility with indoor systems (such as WiFi)- if you get a signal from anything you get some location info.  Don't wait for it, but progress is being made. 

For geocaching, I've found GPS does a great job.  There is the one in Buck's though, and another in a cave... 

-=Chris 

geowanking-bounces at lists.burri.to wrote on 09/20/2007 10:12:16 AM:

> Jeremy,
> 
> You wrote: " I personally think that there should be a Local Positioning
> System technology out there that uses triangulation. Although WiFi and
> Cell Tower positioning are novel there's no way I see either idea being
> able to help me find a geocache or any other specific point. There is
> interesting research in indoor navigation but nothing solid has
> presented itself that I know of yet."
> 
> I always wondered if the positioning principles in GPS and other
> satellite positioning systems could be applied to a system of tower's on
> the Earth's surface, that broadcast similar signals. It seems like this
> would be an affordable way to produce a "local positioning system" and
> the technology for radio signal generation, broadcast, reception and
> processing already exist.
> 
> I wonder if this would be a way to overcome the challenges of
> positioning in urban canyons or heavy forest canopy. You might even be
> able to install the signal broadcasters on existing cell towers, water
> towers, and other structures, which would greatly reduce the cost.
> 
> But maybe there is a technical reason why this will not work.
> 
> Landon (A.K.A. - The Sunburned Surveyor)
> 
> -----Original Message-----
> From: geowanking-bounces at lists.burri.to
> [mailto:geowanking-bounces at lists.burri.to] On Behalf Of Jeremy Irish
> Sent: Thursday, September 20, 2007 10:03 AM
> To: geowanking at lists.burri.to
> Subject: RE: [Geowanking] So do we entirely believe this?
> 
> In some ways I wish the US would create some controversy so it could
> re-invigorate Galileo. The EU seems to be increasingly disinterested in
> a competing system and removing the SA feature from satellites just
> makes Galileo less interesting. At least there's the Russian GLONASS
> system being retooled and China's Compass system (which is still
> undefined).
> 
> I personally think that there should be a Local Positioning System
> technology out there that uses triangulation. Although WiFi and Cell
> Tower positioning are novel there's no way I see either idea being able
> to help me find a geocache or any other specific point. There is
> interesting research in indoor navigation but nothing solid has
> presented itself that I know of yet. Please prove me wrong!
> 
> Jeremy
> 
> -----Original Message-----
> From: geowanking-bounces at lists.burri.to
> [mailto:geowanking-bounces at lists.burri.to] On Behalf Of Tyler Bell
> Sent: Wednesday, September 19, 2007 5:10 PM
> To: geowanking at lists.burri.to
> Subject: Re: [Geowanking] So do we entirely believe this?
> 
> Here's a bit of topical background to the issue from El Reg for
> interested, uh, 'wankers....
> http://www.theregister.co.uk/2007/07/18/drop_sa_say_satnav_lovers/
> 
> - - TB
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