mobile phones

On Mar 4, 4:37 pm, "Peter" wrote:
What is the maximum altitude (about) when the mobile phone becomes useless?
PeterK

I've had it ring at 2500'agl at which point I told whoever (my wife
and curtly too) that I was busy flying and then shut it off (I forgot
to shut it off prior to launch). If many consider it unsafe to drive
and talk, why do it in the air?

chipsoars wrote:
On Mar 4, 4:37 pm, "Peter" wrote:
What is the maximum altitude (about) when the mobile phone becomes useless?
PeterK

I've had it ring at 2500'agl at which point I told whoever (my wife
and curtly too) that I was busy flying and then shut it off (I forgot
to shut it off prior to launch). If many consider it unsafe to drive
and talk, why do it in the air?

There was a study* done on cell phone use in airliners which determined
that an average of 1-4 calls are made on each commercial flight in the
northeast US. If you can get a signal at 35,000 feet inside an aluminum
spam can, I'm sure you can get one just about anywhere in your glider.

* Briefly mentioned on http://www.post-gazette.com/pg/06060/662669.stm , I
didn't find the original study.

--
Michael Ash
Rogue Amoeba Software

chipsoars wrote:
On Mar 4, 4:37 pm, "Peter" wrote:
What is the maximum altitude (about) when the mobile phone becomes
useless? PeterK

It varies enormously in the USA. My experience is the closer I get to a
big city, the lower I have to be to get a signal, maybe 3000' agl. In
the country, I've used it at 15,000' agl during wave flights. My
explanation is the smaller cells and lower powers used in areas with a
lot of people just don't reach upwards very high.

I've had it ring at 2500'agl at which point I told whoever (my wife
and curtly too) that I was busy flying and then shut it off (I forgot
to shut it off prior to launch). If many consider it unsafe to
drive and talk,

Driving requires constant attention because obstacles are so close to
you, like oncoming traffic and the ditch beside the road. This isn't
true for most glider flying. So, it's easier to do safely.

why do it in the air?

I usually do it because I can't reach my crew on the radio; e.g., my
radio or theirs has failed, I am too far away, or there's a mountain in
the way. Recently, our local ASOS was off the air but it still reported
over it's phone number - most pilots dialed it up when they were inbound
for a landing.

I don't suggest using it to chit-chat, or when you need to concentrate
on flying the glider, but if it will significantly improve your safety,
it seems like a good use of the phone.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

While sitting around yesterday morning sipping coffee with the Caracole
group(Cal City), the conversation came up again about the use of mobile
phones as an alternate to radio communications namely when we loose them.
Most of us that fly cross country may have experienced this phenomena and it
is a rather lonely feeling when for example we fly over the decollate Nevada
sky and our crews are trying to follow us through rugged mountains.This loss
of contact may cause us to land prematurely as this is the responsible thing
to do in respect to the crew when we lose total contact. I admit have tried
to use my mobile phone (voice) while flying in the passed but never with
much success.
But than Cindy Brickner (once again) comes up with this idea of text
messaging! As far as I understand her thoughts correctly ( I never sent a
text message in my life), if the pilot or crew sends a short text message
even if there is just a week signal the message will go through in a matter
of second. The same way as soon as there is the slightest signal on their
other end it will be received.
I am certainly not advocating this method as an everyday remedy but
certainly would be better than calling out on 121.5 for assistance and maybe
alarming a bunch of folks (as I read previously onR.A.S.) I would like your
thoughts once again. PeterK
"Eric Greenwell" wrote in message
news:wCIGh.1223$mI6.1220@trndny08...
chipsoars wrote:
On Mar 4, 4:37 pm, "Peter" wrote:
What is the maximum altitude (about) when the mobile phone becomes
useless? PeterK

It varies enormously in the USA. My experience is the closer I get to a
big city, the lower I have to be to get a signal, maybe 3000' agl. In
the country, I've used it at 15,000' agl during wave flights. My
explanation is the smaller cells and lower powers used in areas with a
lot of people just don't reach upwards very high.

I've had it ring at 2500'agl at which point I told whoever (my wife and
curtly too) that I was busy flying and then shut it off (I forgot
to shut it off prior to launch). If many consider it unsafe to
drive and talk,

Driving requires constant attention because obstacles are so close to you,
like oncoming traffic and the ditch beside the road. This isn't true for
most glider flying. So, it's easier to do safely.

why do it in the air?

I usually do it because I can't reach my crew on the radio; e.g., my radio
or theirs has failed, I am too far away, or there's a mountain in the way.
Recently, our local ASOS was off the air but it still reported over it's
phone number - most pilots dialed it up when they were inbound for a
landing.

I don't suggest using it to chit-chat, or when you need to concentrate on
flying the glider, but if it will significantly improve your safety, it
seems like a good use of the phone.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly
* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

Both text messages and some 911 calls will go through with much weaker
signals than needed to complete a regular call.

911 operators will relay non-emergency messages if you explain the
problem.

Mike

On Mar 4, 8:58 pm, "Mike the Strike" wrote:


Both text messages and some 911 calls will go through with much weaker
signals than needed to complete a regular call.


Mike


Why?
Is this a technical fact or just a wishfull speculation?

rk

snip Is this a technical fact or just a wishfull speculation? /
snip

It is a technical fact.

Both user equipment (your handheld mobile) and radio base stations
(what they talk to) have signal thresholds for "quality of service"
that must be met for normal calls (what you're paying for) to go
through. These thresholds are MUCH lower for text and emergency calls
for obvious reasons: text messages have no real-time requirements (and
much lower bandwidth requirements), and emergency calls are, well,
emergency calls; who cares about quality of service if it's an
emergency.

Additionally, normal calls are expected to use low uplink (transmit)
power levels on average, but they still require a lot more than text
messages. With modern mobile systems, power usage is EVERYTHING. If an
emergency call is placed (the system is 911-aware), this power
requirement is relaxed or ignored, in addition to the downlink
(incoming) signal-to-noise ratio thresholds.

-ted/2NO (former 3GPP Ericsson programmer)

p.s. the 3GPP specification can be browsed he http://www.3gpp.org/specs/specs.htm.

While most of the USA doesn't yet use 3GPP, the power usage designs
are prevalent in other, earlier technologies.

Tuno wrote:
snip Is this a technical fact or just a wishfull speculation? /
snip

It is a technical fact.

Both user equipment (your handheld mobile) and radio base stations
(what they talk to) have signal thresholds for "quality of service"
that must be met for normal calls (what you're paying for) to go
through. These thresholds are MUCH lower for text and emergency calls
for obvious reasons: text messages have no real-time requirements (and
much lower bandwidth requirements), and emergency calls are, well,
emergency calls; who cares about quality of service if it's an
emergency.

This is quite similar to the ham radio operator voice vs morse code
situation. While the signal strengths of both types of signals from a
single transmitter will be identical, the *usable* signal strength for
code is much less. This is because if a signal is weak or if there is a
lot of background noise, it is is much easier to detect dots and dashes
than voice.

Tony V.
morse code, RIP :-)

Mike the Strike wrote:
Both text messages and some 911 calls will go through with much weaker
signals than needed to complete a regular call.

There was a good example of this recently in NZ. A girl rolled her car
and ended 3.5m down a bank with the car upside down and supported over a
river by the bank and some trees, which were evidently fairly thin,
because she wasn't about to try getting out in case the car fell into
the river while she was getting out.

Her phone wouldn't raise anybody, including emergency services, due to
poor signal from where she was, but she was able to text a friend, who
passed the emergency call on.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |