mobile phones

[Peter[_4_]]

What is the maximum altitude (about) when the mobile phone becomes useless?
PeterK

[chipsoars]

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?

[Michael Ash]

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

[Tuno]

Depends on the type of cell phone (2d generation, 3GPP etc) and where
you're flying.

My phone (model LG 8300) with Verizon service stops working in central
Arizona above pattern altitude. But it works great in the boonies of
Nevada all the way up to the 17,999'.

~ted/2NO

[jeplane]

The answer to your question will depend on what type of phone you
operate, the area you are in, or even the type of airplane, which
might interfere with reception.

However, you should not forget that the use of cell phones aboard
airborne aircrafts is banned by the FCC in 47 C.F.R. § 22.925:
(Oct 1, 2006 revision) states "Cellular telephones installed in or
carried aboard airplanes, balloons or any other type of aircraft must
not be operated while such aircraft are airborne. When any aircraft
leaves the ground, all cellular telephones on board that aircraft must
be turned off."

Richard
ASW19
Phoenix AZ

[Eric Greenwell]

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

[[email protected]]

I really wish I could carry my cell phone and use in flight as safety
backup to contact the glider port etc. if out of radio range. But all
that space taken up by the paper copies of the FCC and FAA CFR's just
does not leave space for my cell phone in the cockpit... :-)

Darryl

On Mar 4, 3:23 pm, "jeplane" > wrote:
> The answer to your question will depend on what type of phone you
> operate, the area you are in, or even the type of airplane, which
> might interfere with reception.
>
> However, you should not forget that the use of cell phones aboard
> airborne aircrafts is banned by the FCC in 47 C.F.R. § 22.925:
> (Oct 1, 2006 revision) states "Cellular telephones installed in or
> carried aboard airplanes, balloons or any other type of aircraft must
> not be operated while such aircraft are airborne. When any aircraft
> leaves the ground, all cellular telephones on board that aircraft must
> be turned off."
>
> Richard
> ASW19
> Phoenix AZ

[Tony Verhulst]

> If many consider it unsafe to drive
> and talk, why do it in the air?

Well, I don't but, some would answer because it is unusual to be passing
obstructions at high speed an arms length away in a glider - gaggles not
withstanding.

Tony V.

[Peter[_4_]]

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

[Mike the Strike]

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

[Bill Daniels]

"chipsoars" > wrote in message
oups.com...
> 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?
>

First, there are hundreds of thousands of pilots trained to verbally copy
and read back complicated airtraffic clearances while flying extremely
complex aircraft. For these pilots, a duplex phome conversation while
flying a simple glider is childs play. However, if it bothers you, don't do
it.

BTW, I don't think using satellite phones aboard an aircraft is prohibited
by FCC regulations.

Bill D

[Tuno]

*yawn* It's also against the law to loiter within the walls of
Chester, England after sunset.

Old debates ...

~tuno

[Marc Ramsey]

jeplane wrote:
> However, you should not forget that the use of cell phones aboard
> airborne aircrafts is banned by the FCC in 47 C.F.R. § 22.925:
> (Oct 1, 2006 revision) states "Cellular telephones installed in or
> carried aboard airplanes, balloons or any other type of aircraft must
> not be operated while such aircraft are airborne. When any aircraft
> leaves the ground, all cellular telephones on board that aircraft must
> be turned off."

47 CFR 22.295 applies only to "cellular telephones" (i.e. the old analog
things that operated in the 800 MHz band) licensed under Part 22. Most
of us now carry PCS (personal communications services) phones licensed
under Part 24, and as far as I can tell, the FCC has no regulations
against their use in flight...

Marc

[Tuno]

As Mike said, text messages and some 911 signals require much less
power and signal to go through. (Mobile phone software enforces a
"quality of service" threshold; if it cannot be met or exceeded for a
voice call, it will not go through, but this threshold is very
different for text and emergency calls.)

I landed out ~50 miles south lf Moriarty a couple of years ago and my
mobile didn't work; it showed a weak analog signal but wouldn't place
calls. But 911 worked, and when I explained by situation to the
operator, she got called my crew number and we got hooked up.

~ted/2NO

[Lew Hartswick]

Tuno wrote:
> As Mike said, text messages and some 911 signals require much less
> power and signal to go through. (Mobile phone software enforces a
> "quality of service" threshold; if it cannot be met or exceeded for a
> voice call, it will not go through, but this threshold is very
> different for text and emergency calls.)
>
> I landed out ~50 miles south lf Moriarty a couple of years ago and my
> mobile didn't work; it showed a weak analog signal but wouldn't place
> calls. But 911 worked, and when I explained by situation to the
> operator, she got called my crew number and we got hooked up.
>
> ~ted/2NO
>
Where were you? about Claunch? That is some desolate country.
...lew...

[Tuno]

< Where were you? about Claunch? That is some desolate country. >

Lincoln Station, maybe 15 miles east of Claunch. I wonder if my wing
stand is sitll there ...

[Mike the Strike]

On Mar 4, 7:51 pm, "Tuno" > wrote:
> *yawn* It's also against the law to loiter within the walls of
> Chester, England after sunset.
>
> Old debates ...
>
> ~tuno


Only if you're Welsh - I used to live in Chester and loitered there
frequently after dark!

Mike

[Malcolm Austin]

Is that what I can see on Google Earth? :-)



"Tuno" > wrote in message
oups.com...
>< Where were you? about Claunch? That is some desolate country. >
>
> Lincoln Station, maybe 15 miles east of Claunch. I wonder if my wing
> stand is sitll there ...
>

[Eric Greenwell]

Marc Ramsey wrote:
> jeplane wrote:
>> However, you should not forget that the use of cell phones aboard
>> airborne aircrafts is banned by the FCC in 47 C.F.R. § 22.925:
>> (Oct 1, 2006 revision) states "Cellular telephones installed in or
>> carried aboard airplanes, balloons or any other type of aircraft must
>> not be operated while such aircraft are airborne. When any aircraft
>> leaves the ground, all cellular telephones on board that aircraft must
>> be turned off."
>
> 47 CFR 22.295 applies only to "cellular telephones" (i.e. the old analog
> things that operated in the 800 MHz band) licensed under Part 22. Most
> of us now carry PCS (personal communications services) phones licensed
> under Part 24, and as far as I can tell, the FCC has no regulations
> against their use in flight...

My cursory Google search backs up Marc's comments (not that I doubted
him - I was just curious about the details). So, unless someone can find
contrary documents, this may be the end of one of our favorite perennial
threads. May "Cell phone use in gliders" rest in peace.

And perhaps it's time to call them "mobile phones" instead of "cell
phones". I thing the Europeans have done that for years, already.

--
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

[Brian[_1_]]

>
> > why do it in the air?
>
I've done it to call the Tower and get a landing clearance after my
radio faile

Brian

[Michael Ash]

Eric Greenwell > wrote:
> Marc Ramsey wrote:
>> jeplane wrote:
>>> However, you should not forget that the use of cell phones aboard
>>> airborne aircrafts is banned by the FCC in 47 C.F.R. ? 22.925:
>>> (Oct 1, 2006 revision) states "Cellular telephones installed in or
>>> carried aboard airplanes, balloons or any other type of aircraft must
>>> not be operated while such aircraft are airborne. When any aircraft
>>> leaves the ground, all cellular telephones on board that aircraft must
>>> be turned off."
>>
>> 47 CFR 22.295 applies only to "cellular telephones" (i.e. the old analog
>> things that operated in the 800 MHz band) licensed under Part 22. Most
>> of us now carry PCS (personal communications services) phones licensed
>> under Part 24, and as far as I can tell, the FCC has no regulations
>> against their use in flight...
>
> My cursory Google search backs up Marc's comments (not that I doubted
> him - I was just curious about the details). So, unless someone can find
> contrary documents, this may be the end of one of our favorite perennial
> threads. May "Cell phone use in gliders" rest in peace.

It would make sense (not that we necessarily expect the FAA to make
sense). My understanding is that the major problem with cell phones on GA
craft was simply that the old-style cell networks couldn't handle them. An
active cell phone in the air would be within range of a bunch of different
towers which caused confusion in the network, since it was built on the
assumption that the ground would limit your line of sight so that you
would only be in range of two or three towers at a time.

Modern networks don't have this problem so this reason goes away. Of
course there's still the issue of interference with avionics and such
which is why they're still banned on airliners, although as I noted in a
previous post, it seems that this ban isn't all that effective. For most
GA pilots the interference thing isn't too important, since even if you
did need them and even if they did start going wonky, you can always just
turn off the phone.

--
Michael Ash
Rogue Amoeba Software

[Jeremy Zawodny]

Peter wrote:
> What is the maximum altitude (about) when the mobile phone becomes useless?

I made a call while thermaling at 16,000 in Parowan a few years ago.

Jeremy

[[email protected]]

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

[Tuno]

<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)

[Tuno]

p.s. the 3GPP specification can be browsed here: 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.

[309]

Michael Ash wrote:
>
> My understanding is that the major problem with cell phones on GA
> craft was simply that the old-style cell networks couldn't handle them. An
> active cell phone in the air would be within range of a bunch of different
> towers which caused confusion in the network, since it was built on the
> assumption that the ground would limit your line of sight so that you
> would only be in range of two or three towers at a time.
>

There are also interference issues with AIRCRAFT SYSTEMS.

At an FAA DER Seminar a couple of years ago, they pointed out that
some "phones" would transmit spurrious signals off their frequency
that could couple with antenna cables (shielded or not), and interfere
with aircraft navigation systems (mainly VOR). It's not as simple as
many think (and I'm an aero guy, not an electron guy, so I won't
pretend to really understand).

I was on a test flight where we determined that our telemetry
transmitter COMPLETELY wiped out the reception of our $25,000.00
Ashtech GPS receiver.

Older phones (and older aircraft equipment) tend to wander off of
their original specifications. While most gliders don't rely on VOR,
but rather GPS for navigation (some of us use windows, charts and
eyeballs), the interference from "phones" may not be as much an issue
-- but we've shown that it can be.

The FAA guy indicated that a particular Samsung phone (now off the
market, I'm told) could completely trash com and nav functions on an
airlner type "ship." Autopilots have been affected, too. "Hardening"
transport (airline) aircraft systems (for new models) is a serious
consideration in this modern world of emitters, but always needs to be
balanced against cost, weight and performance. Also, putting small
"pico" cells (a small cell "tower") ONBOARD the aircraft seems to
help: the closer tower causes the phone to shift into a lower power
consumption mode (i.e., lower transmit power, which translates into
less interference).

Caution is advised. It would be a shame if your 1000k log was trashed
when you called Mom to tell her you finally did it...

-Pete
#309

[Tom Gardner[_1_]]

"309" > wrote in
oups.com:
> There are also interference issues with AIRCRAFT SYSTEMS.

Most definitely. The only question is "how serious".

> At an FAA DER Seminar a couple of years ago, they pointed out that
> some "phones" would transmit spurrious signals off their frequency
> that could couple with antenna cables (shielded or not), and interfere
> with aircraft navigation systems (mainly VOR). It's not as simple as
> many think (and I'm an aero guy, not an electron guy, so I won't
> pretend to really understand).

The root cause is that most of the objects in the world don't
behave like a nice simple ohmic resistor where V=IR. In practice
I=f(V), where function f can typically be exponential, but can
be virtually any function.

Examples of non-linear objects: semiconductors, joints between
some metals, rusty bolts, mercury amalgam fillings, magnetic
components (e.g. transformers) and there are many others!

So what? Well, it turns out that this has two main consequences:
1 if there are two RF frequencies f1 and f2 impinging on the
non-linear object then the object will multiply the two
frequencies and radiate the results at harmonics of the
frequencies and of the sum and difference frequencies
(and harmonics of the sum and difference frequencies).
2 RF power can be rectified to produce a DC offset

The re-radiated frequencies due to (1) are unpredictable
in practice and splattered across band allocated to other
RF services. Example: warships can't use all their
RF equipment separately due to the rusty bolt problem.
HMS Sheffield was sunk by an Exocet because satellite
comms couldn't happen when the primary radar was on, and
that was the time at which the Exocet was launched.

(2) may or may mot be a problem. Typical electronic equipment
is able to cope with constant DC offsets associated with
constant RF power. But there are problems with varying RF power.

CDMA cellphones largely keep their tx power constant,
varying it slightly and occasionally when the transmission
path changes.

TDMA systems (e.g. GSM) have pulsed RF tx power at 217Hz
1/8 duty cycle and 8 times peak power. Put one of these
near to a phone or hifi or hearing aid and the results
are clearly audible. Such interference can completely
disrupt the operation of some equipment.

[chipsoars]

On Mar 7, 5:09 am, Tom Gardner > wrote:
> "309" > wrote groups.com:
>
> > There are also interference issues with AIRCRAFT SYSTEMS.
>
> Most definitely. The only question is "how serious".
>
> > At an FAA DER Seminar a couple of years ago, they pointed out that
> > some "phones" would transmit spurrious signals off their frequency
> > that could couple with antenna cables (shielded or not), and interfere
> > with aircraft navigation systems (mainly VOR). It's not as simple as
> > many think (and I'm an aero guy, not an electron guy, so I won't
> > pretend to really understand).
>
> The root cause is that most of the objects in the world don't
> behave like a nice simple ohmic resistor where V=IR. In practice
> I=f(V), where function f can typically be exponential, but can
> be virtually any function.
>
> Examples of non-linear objects: semiconductors, joints between
> some metals, rusty bolts, mercury amalgam fillings, magnetic
> components (e.g. transformers) and there are many others!
>
> So what? Well, it turns out that this has two main consequences:
> 1 if there are two RF frequencies f1 and f2 impinging on the
> non-linear object then the object will multiply the two
> frequencies and radiate the results at harmonics of the
> frequencies and of the sum and difference frequencies
> (and harmonics of the sum and difference frequencies).
> 2 RF power can be rectified to produce a DC offset
>
> The re-radiated frequencies due to (1) are unpredictable
> in practice and splattered across band allocated to other
> RF services. Example: warships can't use all their
> RF equipment separately due to the rusty bolt problem.
> HMS Sheffield was sunk by an Exocet because satellite
> comms couldn't happen when the primary radar was on, and
> that was the time at which the Exocet was launched.
>
> (2) may or may mot be a problem. Typical electronic equipment
> is able to cope with constant DC offsets associated with
> constant RF power. But there are problems with varying RF power.
>
> CDMA cellphones largely keep their tx power constant,
> varying it slightly and occasionally when the transmission
> path changes.
>
> TDMA systems (e.g. GSM) have pulsed RF tx power at 217Hz
> 1/8 duty cycle and 8 times peak power. Put one of these
> near to a phone or hifi or hearing aid and the results
> are clearly audible. Such interference can completely
> disrupt the operation of some equipment.

is that the reason why when from time to time my Motorola GSM phone
pulses (not necessarily for a call) I can hear the pulse through my
computer, car radio etc? If so, that could be an issue for
instruments and radio in the aircraft if I understand this correctly.

[Tony Verhulst]

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 :-)

[Tom Gardner[_1_]]

"chipsoars" > wrote in
ps.com:

> On Mar 7, 5:09 am, Tom Gardner > wrote:
>> TDMA systems (e.g. GSM) have pulsed RF tx power at 217Hz
>> 1/8 duty cycle and 8 times peak power. Put one of these
>> near to a phone or hifi or hearing aid and the results
>> are clearly audible. Such interference can completely
>> disrupt the operation of some equipment.
>
> is that the reason why when from time to time my Motorola GSM phone
> pulses (not necessarily for a call) I can hear the pulse through my
> computer, car radio etc? If so, that could be an issue for
> instruments and radio in the aircraft if I understand this correctly.

I expect so. The GSM interference during call-setup is
"di-di-di, di-di-di, di-di-di, brrr..." duration ~2s.

There can and will be different interference at other
times, e.g. location update, SMS rx/tx, cell handover.

Whether it is a problem for instruments depends on the
amount of power coupled into the instrument (filtering,
orientation, range) and whether is is susceptable to
217Hz changes in DC offset.

How loud it sounds is a strong function of distance,
falling off at somewhere between r^4 and r^8; test
it with you phone and hifi

[Tom Gardner[_1_]]

Tony Verhulst > wrote in
:

> 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.

In addition,
- all other things being equal, at low SNR AM gives a
better quality than FM
- morse code can operate with a narrower RF bandwidth,
thus reducing noise and increasing SNR

[309]

Tom Gardner wrote:

> > is that the reason why when from time to time my Motorola GSM phone
> > pulses (not necessarily for a call) I can hear the pulse through my
> > computer, car radio etc? If so, that could be an issue for
> > instruments and radio in the aircraft if I understand this correctly.
>
> I expect so. The GSM interference during call-setup is
> "di-di-di, di-di-di, di-di-di, brrr..." duration ~2s.
>

I've been told that BlackBerry's are notorious for this
interference.

Can one "phone"(/device) interfere with another in this manner?

During the frequent telecons I must attend (since travel budget was
cut), we frequently hear the pesky "di-di-di--brrrr" you've described.

One might extend this conversation to the thousands of PDA's that are
semi-permanent (and unapproved?) additions to glider instrument panels
(yes, I plead guilty as charged). But perhaps only if they have
wireless (e.g. BlueTooth) capability?

For personal/work reasons, I have gravitated to PDA's without wireless
-- and similarly had to hunt for a cell phone withOUT a
camera...trying to stay non-converged (diverged?) in this convergent
world is a pain.

Remember that old saying? "Aircraft fly because of Bernoulli, not
Marconi..."

-Pete
#309

[Tom Gardner]

On Mar 7, 3:45 pm, "309" > wrote:

> I've been told that BlackBerry's are notorious for this
> interference.
> Can one "phone"(/device) interfere with another in this manner?

I don't know enough about BlackBerries to comment.

> One might extend this conversation to the thousands of PDA's that are
> semi-permanent (and unapproved?) additions to glider instrument panels
> (yes, I plead guilty as charged). But perhaps only if they have
> wireless (e.g. BlueTooth) capability?

Bluetooth's tx power is suitable for a few yards only, and so can
be much lower power. This would reduce the probability of
interference
causing problems.

Personally I'd ensure any non-essential radio is completely off
before I'm airborne.

Practical testing is always useful, provided one realises that
testing can only demonstrate problems, not prove the absence
of problems.

[Michael Ash]

309 > wrote:
>
> Michael Ash wrote:
>>
>> My understanding is that the major problem with cell phones on GA
>> craft was simply that the old-style cell networks couldn't handle them. An
>> active cell phone in the air would be within range of a bunch of different
>> towers which caused confusion in the network, since it was built on the
>> assumption that the ground would limit your line of sight so that you
>> would only be in range of two or three towers at a time.
>
> There are also interference issues with AIRCRAFT SYSTEMS.

Certainly. But there is a big difference between airliners and GA craft
when it comes to this, namely the fact that in GA craft the use of cell
phones will be obvious to the pilot and he can politely ask the passenger
to put it away, or he can get off the phone himself. The range of
instrumentation will also be much more varied. When I'm flying there
should be no interference issues since the only electronic stuff in the
glider is the aircraft radio. If I were to use the phone and it were to
start messing with the radio, I can always hang up. Airliners have a lot
more instrumentation and the use of forbidden objects is harder to detect,
so the rules are more strict.

--
Michael Ash
Rogue Amoeba Software

[Eric Greenwell]

309 wrote:

>
> Caution is advised. It would be a shame if your 1000k log was trashed
> when you called Mom to tell her you finally did it...

I've not seen any interference from my mobile phone (analog or digital
mode) with the GPS or radio. Has anyone had a problem?

--
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

[Eric Greenwell]

309 wrote:

> One might extend this conversation to the thousands of PDA's that are
> semi-permanent (and unapproved?) additions to glider instrument panels
> (yes, I plead guilty as charged).

My understanding is "approval" isn't required for general aviation use,
because PDA's are portable devices (like a handheld radio, GPS, and
oxygen), and the only requirement is the pilot determine they do not
cause interference.

This doesn't mean we can't think of ways to cause ourselves trouble with
some of our mounting methods. I was guilty of mounting a GPS antenna on
the glare shield, which would've affected the canopy jettison. I've
removed the antenna to a better location, and when I mounted my MRX
transponder detector on the glare shield, I used a connector that
releases easily.

--
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

[47Dodge]

Michael Ash wrote:

> Airliners have a lot more instrumentation and the use of
> forbidden objects is harder to detect, so the rules are more strict.

Not to mention the potential cumulative effect of two hundred energy
radiators operating at the same time.


Jack

[[email protected]]

> I've not seen any interference from my mobile phone (analog or digital
> mode) with the GPS or radio. Has anyone had a problem?

Yes, my Motorola Razr trashes my Garmin 96!

Best regards,

Jer/ "Flight instruction and mountain flying are my vocations!"
--
Jer/ (Slash) Eberhard, Mountain Flying Aviation, LTD, Ft Collins, CO
CELL 970 231-6325 EMAIL jer'at'frii.com http://users.frii.com/jer/
C-206, CFII Airplane&Glider, FAA-DEN Aviation Safety Counselor
CAP-CO Mission&Aircraft CheckPilot BM218 HAM N0FZD 247 Young Eagles!

[Martin Gregorie]

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 |

[Roger Worden]

Blackberries definitely cause interference with wired phones in our
conference rooms, but generally only if they're within a foot or two. I
frequently have to remind participants to take them off the table away from
the phones. Then they put them in their briefcases or purses which are
sitting on the phone wire (read: antenna) on the floor... duh!

"309" > wrote in message
ups.com...
>
> Tom Gardner wrote:
>
> > > is that the reason why when from time to time my Motorola GSM phone
> > > pulses (not necessarily for a call) I can hear the pulse through my
> > > computer, car radio etc? If so, that could be an issue for
> > > instruments and radio in the aircraft if I understand this correctly.
> >
> > I expect so. The GSM interference during call-setup is
> > "di-di-di, di-di-di, di-di-di, brrr..." duration ~2s.
> >
>
> I've been told that BlackBerry's are notorious for this
> interference.
>
> Can one "phone"(/device) interfere with another in this manner?
>
> During the frequent telecons I must attend (since travel budget was
> cut), we frequently hear the pesky "di-di-di--brrrr" you've described.
>
> One might extend this conversation to the thousands of PDA's that are
> semi-permanent (and unapproved?) additions to glider instrument panels
> (yes, I plead guilty as charged). But perhaps only if they have
> wireless (e.g. BlueTooth) capability?
>
> For personal/work reasons, I have gravitated to PDA's without wireless
> -- and similarly had to hunt for a cell phone withOUT a
> camera...trying to stay non-converged (diverged?) in this convergent
> world is a pain.
>
> Remember that old saying? "Aircraft fly because of Bernoulli, not
> Marconi..."
>
> -Pete
> #309
>
>