Roger 2008 wrote:
> "D" <noemail@respondhere.com> wrote in message
> news:f9pdv358q4d767lpi21ua63eouhaap4gqa@4ax.com...
>> On Fri, 04 Apr 2008 21:12:28 -0400, "Richard B. Gilbert"
>> <rgilbert88@comcast.net> wrote:
>>
>>> Roger 2008 wrote:
>>>> "Gordon Burditt" <gordonb.sh6xy@burditt.org> wrote in message
>>>> news:XrOdnYKg7an-52vanZ2dnUVZ_vOlnZ2d@internetamerica...
>>>>
>>>>>> Please do not forget who the original poster was and his questions:
> He
>>>>>> asked:
>>>>>> "can I display my own LAT/LON values somehow without a map application
> ?"
>>>>> For some cell phone implementation of "GPS" (this one doesn't involve
>>>>> actual satellites talking to your phone), your position coordinates
>>>>> are present at the cell towers and somewhere in the offices of Big
>>>>> Brother, but not on your cell phone. If a map application can get
>>>>> your position at all, it has to ask your cell provider to send it,
>>>>> and that may cost money.
>>>>
>>>> Oh yeah, now that you mention it. My first camera phone called it GPS
> but
>>>> when you read further about it, it was just using cell phone towers.
>>>>
>>>> BTW I have met a person with an iPHONE that thinks his phone has GPS
> and he
>>>> even showed me "Google Maps for Mobile" on it.
>>>>
>>>> I thought he had a messed up GPS reading because it had us way across
> the
>>>> street and then I learned later the iPHONE uses cell phone towers for
> an
>>>> approximate location on "Google Maps for Mobile."
>>>>
>>>>
>>> GPS, or at least the civilian version of it, is only accurate to within
>>> about 300 feet or 100 meters. I once did a "site survey" using a
>>> Motorola M12+T GPS timing receiver. The software I used plotted
>>> something like 10,000 position readings on the map. The result was a
>>> strip about 10 meters wide and 100 meters long and oriented ENE-SSW. My
>>> antenna was more or less in the middle of this mess.
>>>
>>> The military uses a different set of signals from the same satellite and
>>> gets accurracy good enough for weapons targeting. This level of GPS is
>>> available only to the military and certain defense contractors. Us
>>> lowly civilians can't get it.
>>>
>>> As far as I know, a cell phone tower has no means of determining the
>>> direction your signal is coming from.
>> Towers cannot tell what direction the signal is coming from, but can
>> tell from relative power how far away it is, and form a circle based
>> on that reading. For sake of argument, say you are 3 miles from
>> tower one, and 5 miles from tower two. there are only two places you
>> can be 3 milies and 5 miles from the towers. Add a third tower, and
>> you only have one place you can be. That is how triangulation (hence
>> the tri - three) works.
>
> With no disrespect for the poster that started this thread then how does VOR
> for airplanes work from one transmitting site?
>

Not the OP but VOR is a positioning system by design. You can establish
a LOP because your VOR receiver measures the phase difference of the 0
deg reference signal and the rotating signal from the station. That
phase difference is the radial you are on and what the VOR receiver
displays. To further enhance things they often colocate DME at the VOR
site. An additional unit in the airplane sends an interrogation to the
ground station which then replies. The airborne unit uses the transit
time to deduce its distance from the station.


> More on VOR can be found at:
> http://www.pilotfriend.com/training/...v_overview.htm
>
> But the above site doesn't come right out and say if they use more than one
> transmitting tower to get VOR to work.
>
> I have been under the assumption that since most cellphone towers have three
> elements that the cellphone knew that it was 1 of 3 directions away from the
> tower but now it seems there is nothing VOR related in cell phone towers.
>
>