It's probably no surprise to anyone that cell phones can be tracked even
when they are not being used in a call. You can Google "Cell Phone
Tracking" and get enough information for a long evenings reading.

My carrier, Verizon, offers "VZ Navigator" a $10/mo service which enables my
GPS equipped cellphone to automatically send SMS messages with location data
to another cell phone every few minutes. If the receiving phone is equipped
with the same service, the location data is displayed on a moving map. It's
described as a way for parents to keep track of children. The main news
concerns privacy issues but the service can be turned on and off by the
user.

Third party services offer to put location data on the internet so anyone
with access can see the location real-time. It's not hard to imagine
practical uses for locating a glider pilot (or his crew) during and after a
flight. For example, if a pilot enables this service, his crew could track
the flight real-time. It appears that it works anywhere SMS messaging
works.

Bill Daniels

I'm a Verizon customer, and the only place I've been able to get my
phone to work in a glider above pattern altitude is in areas where SMS
does not work. Maybe that will change someday ...

-ted/2NO

"Tuno" > wrote in message
oups.com...
> I'm a Verizon customer, and the only place I've been able to get my
> phone to work in a glider above pattern altitude is in areas where SMS
> does not work. Maybe that will change someday ...
>
> -ted/2NO
>

Does the GPRS work at altitude.

http://www.silentwings.no/article/articleview/106/1/1//

> Does the GPRS work at altitude.

Nope.

If I recall correctly from my base station programming days, GPRS is
the bearer channel for SMS, so if SMS isn't working, it will almost
certainly be because a GPRS channel cannot be opened. I think
Verizon's GPRS only works in areas where it can be executed with lower
power consumption, which means being close to the ground radios. I'm
very curious whether other service providers can do SMS at altitude
(or any other packet-switched service).

My GPS tracking phones I use to track my small fleet of trucks do not
show altitude. They only show location and speed and you can overlay
tracking on a map (on the web). Last weekend my track from Cal City
to Mt. Whittney and back to WJF & L71 showed up quite nice. The phone
receives GPS and every 15 min it sends via a cell call to a server the
phone position stored every 5 minutes. I can ping the phone and get
on demand location & speed if the phone can contact the cell site. If
the cell phone cannot contact a cell site it will store until it does
and than down load all stored points. If I had of landed out in the
Sierras it probably would do me no good except to show last position
tansmitted maybe in the air? If in the Valley it could come in handy
if incompasitated.

I've had pretty good luck in remote areas while airborne. Apparently, SMS
works when voice calls are not possible. But then, in Colorado, cell towers
are located on mountain peaks. As I understand it, if SMS service is not
avaliable, the 'phone will hold the message until it is and then send it.
The message gets through even if not in real-time.

The only way to know if tracking works is to try it.

Bill Daniels


"Tuno" > wrote in message
oups.com...
> I'm a Verizon customer, and the only place I've been able to get my
> phone to work in a glider above pattern altitude is in areas where SMS
> does not work. Maybe that will change someday ...
>
> -ted/2NO
>

Bill Daniels wrote:
> It's probably no surprise to anyone that cell phones can be tracked even
> when they are not being used in a call. You can Google "Cell Phone
> Tracking" and get enough information for a long evenings reading.
>

This handy application will let you locate just by entering a phone
number. Give it a try...

http://www.sat-gps-locate.com/

Mal wrote:

>
> "Tuno" > wrote in message
> oups.com...
>> I'm a Verizon customer, and the only place I've been able to get my
>> phone to work in a glider above pattern altitude is in areas where SMS
>> does not work. Maybe that will change someday ...
>>
>> -ted/2NO
>>
>
> Does the GPRS work at altitude.
>

Here is a simple overview of the factors for marginal
GSM coverage. I hope it's useful and not too boring.


Wether or not you'll get a signal depends mostly on the basestation
antenna radiation pattern. The operators normally use directional
antennas, covering the ground of the cell only.

Some of that gets reflected upwards, but that coverage is patchy.
There are of course situations where a basestation has been pointed
skywards (e.g. illuminating the side of a mountain), so in some rare
parts of the sky GSM works well.

Now, SMS uses the GSM control channel, the one which is also used
to establish a call. This channel has a very simple protocol, very
much like humans do radio communication - listen and if nobody else
talks, talk.

It only takes a small patch of coverage for an SMS to get through.
Also, as others have pointed out, the phone will hold a SMS until
it finds such a patch.

For a phone call proper, you need essentially uninterrupted coverage
for the duration of the call. In principle, if an SMS can get through
you can start a call, but it could be extremely short.

GPRS is a data transfer protocol which uses the spare channel capacity,
anything which is not used for calls. Since it's a packet based
protocol (each like very large SMS), it has a slightly better chance
of "getting through" than a phone call.

However, since the packets are larger, the patch of coverage must
last longer. Also, the system will only retry for a few seconds
before giving up. SMS will retry all week is it has to.

Among other things, GPRS is used to transfer the bulk of data
for MMS (pictures, video clips, etc.).


Iwo

On May 8, 3:47 am, Iwo Mergler >
wrote:
> Mal wrote:
>
> > "Tuno" > wrote in message
> oups.com...
> >> I'm a Verizon customer, and the only place I've been able to get my
> >> phone to work in a glider above pattern altitude is in areas where SMS
> >> does not work. Maybe that will change someday ...
>
> >> -ted/2NO
>
> > Does the GPRS work at altitude.
>
> Here is a simple overview of the factors for marginal
> GSM coverage. I hope it's useful and not too boring.
>
> Wether or not you'll get a signal depends mostly on the basestation
> antenna radiation pattern. The operators normally use directional
> antennas, covering the ground of the cell only.
>
> Some of that gets reflected upwards, but that coverage is patchy.
> There are of course situations where a basestation has been pointed
> skywards (e.g. illuminating the side of a mountain), so in some rare
> parts of the sky GSM works well.
>
> Now, SMS uses the GSM control channel, the one which is also used
> to establish a call. This channel has a very simple protocol, very
> much like humans do radio communication - listen and if nobody else
> talks, talk.
>
> It only takes a small patch of coverage for an SMS to get through.
> Also, as others have pointed out, the phone will hold a SMS until
> it finds such a patch.
>
> For a phone call proper, you need essentially uninterrupted coverage
> for the duration of the call. In principle, if an SMS can get through
> you can start a call, but it could be extremely short.
>
> GPRS is a data transfer protocol which uses the spare channel capacity,
> anything which is not used for calls. Since it's a packet based
> protocol (each like very large SMS), it has a slightly better chance
> of "getting through" than a phone call.
>
> However, since the packets are larger, the patch of coverage must
> last longer. Also, the system will only retry for a few seconds
> before giving up. SMS will retry all week is it has to.
>
> Among other things, GPRS is used to transfer the bulk of data
> for MMS (pictures, video clips, etc.).
>
> Iwo

they need to add an altitude feature and get it FAI approved. of
course then they'd probably charge 800 bucks for the phone

Now that's really funny!

"Gary Emerson" > wrote in message
...
> Bill Daniels wrote:
>> It's probably no surprise to anyone that cell phones can be tracked even
>> when they are not being used in a call. You can Google "Cell Phone
>> Tracking" and get enough information for a long evenings reading.
>>
>
> This handy application will let you locate just by entering a phone
> number. Give it a try...
>
> http://www.sat-gps-locate.com/
>