mobile phones

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

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

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.

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

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

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

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

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!

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 |

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