I just read an article where a deer hunter got lost. The search and rescue team stated that they tried to use triangulation to find the lost hunter's cell phone, but there was only one cell tower in the vicinity so they were unsuccessful. They further went on to say that they were able to determine the signal came within a 12 mile radius of the cell tower. Not sure if they meant trilateration instead of triangulation, but eitherway it made me wonder about surveying applications. If they can locate cell phones by triangulation or trilateration from cell towers, what are the possibilities of locating survey points this way?
Maybe this is old news to some of you techno geeks, but would be good to hear your thoughts as I'm not up to date on cell phone location capabilities.
thanks in advance
(by the way, the deer hunter walked out on his own after two days, appears to be in good shape.)
Some people just do not belong in the woods. JRL
Not sure if I exactly understand the question, but my iphone has gps(which I believe utilizes tower triangulation) and I could use it locate points...sometimes within 5'...sometimes within 500'. I think the technology is good to maybe determine a search area to to find a person, but you're going to basically need survey-grade gps to locate a pk nail in the asphalt.
I've always wondered why surveyor's couldn't use local transmitters instead of relying on satillites. I'm sure this has been thought of, but I've never heard the discussion about it from those with a higher understanding of the GPS technology.
For instance, I've envisioned a survey system consisting of 3 or 4 transmitters and one receiver using the same technology as GPS. A surveyor could set up the transmitters around the perimeter of the area to be surveyed, and then the receiver could use trilateration off of those transmitters instead of relying on capturing some weak signal from outer space. Seems too simple, but then I'm kind of a simple kind of guy.
I had a job once down in a deep timbered canyon which was very difficult to traverse using conventional equipment. GPS was unusable due to the canyon walls and the thick timber canopy. It was at that time I thought a self contained system "local gps" setup would be the answer to these kind of jobs and many others. But I've never really discussed it with anyone else than the brush apes I worked with at the time. Like I said, probably has been thought of but not found doable for some reason or another, but then again...?
Locata has been advertising in GPS world. Using "pseudolites" radio signals from ground based transmitters to augment GPS signals. Looks like they have completed many tests and have installed some networks for mining applications. Also see where Leica just bought them out. This ground based GPS augmentation sounds really sweet to me. If the ground based signals are powerful enough to penetrate inside buildings (like a cell phone signal) I'd think the signls would be powerful enough to penetrate thick forests too.
there ya go, the heck with satellites,
I knew it was a good idea when I first thought of it.
thanks for the link Tim.
By the way, anybody want to buy a slightly used gps system? Yours for just taking over the payments ;.)
Remember reading about TV signals a while back also.
OK, so Leica has a "partnership" with Locata. In another article I see that Trimble does too. Could this technology be in our future? Have to wonder about cost to benefit ratios...
maybe a conspiracy to quash the technology or monopolize it.
The problem for finding precise location in buildings and tree canopy isn't just signal strength.
Even if you can get plenty of signal for a cell phone, the locator device will be presented with signals bouncing every which way. Since it can't tell which path the signal took, it can't give accurate and repeatable results.