Paul Saccani wrote:
> On Wed, 17 Sep 2008 23:08:33 +1000, B J Foster
yahoo.com>
> wrote:
> >> Paul Saccani wrote:
>>> On Tue, 16 Sep 2008 08:38:45 +1000, B J Foster
yahoo.com>
>>> wrote:
>>>>>>> Mobile phones use UHF frequencies and do *not* interfere with aircraft
>>>> navigation systems. The issue is that whilst the interference is
>>>> infinitesmally small it cannot be entirely dismissed - so the rule
>>>> remains. In practice it is ridiculous.
>>> I've actually seen mobile phones interfere with VOR, the needle
>>> swinging from side to side until they are turned off.
>> I find this very hard to believe.
>
> I knew that.
>
>> The VOR band is 108MHz to 118Mhz (VHF). The lowest mobile band (UHF) is
>> 900Mhz.
>
> So what is GSM400, GSM450 GSM 800 and GSM850 in that case?
Where are these GSM bands used?
AFAIK, we use 900 and 1800 in Oz
>
> I'll give you a hint - the name is based on the band used.
Don't be rude
>
> I think you don't know that you don't know.
>
> Then there is UMTS on the 700MHz band,
> CDMA 400, 450, 800 and 850 on their respective bands.
CDMA? What's that?
>
>> If the VOR system has such a poor filter then it is going to be
>> affected by *every* *other* system between VOR and GSM.
>
>> For example:
>> 118ق137 MHz: air traffic control
>> 137-138 MHz: meteorological satellites
>> 144ق148 MHz: Amateur radio
>> 156ق158 MHz: VHF Marine Radio
>> 175-216 MHz: television channels 7 - 13
>> 174ق216 MHz: wireless microphones
>>
>> ...and so on...
>
> I can't recall using that equipment to transmit *in* the cockpit of a
> VOR equipped aircraft. Perhaps you fly in a different manner to
> me.....
ATC is the nearest & indeed the next band!
>
> I find your argument lacking.
>
> Common experience should already have alerted you to cell phone
> interference with *audio* amplifiers, let alone radio ones.
As I mentioned that is more likely to be due to the CPU.
Do some research on GSM and the permissible power *outside* the band. It
is negligible.
>
>> NASA and U Okalahoma tested GSM and CDMA extensively and concluded as
>> follows:
>> "None of the 4 CDMA and 4 GSM wireless handsets tested would
>> individually be likely to interfere with aircraft VOR, LOC, GLS,
>> or GPS navigation radios".
>
> I would have thought that was an impossibly small sample size to draw
> conclusions from, especially as there are eight bands used by GSM
> alone! And this study covered only one GSM band, E-GSM900.
Which (happily) happens to be the lowest band used in Oz. In any case
the lowest band you mentioned, 400 MHz (which doesn't exist in
Australia), is sufficiently distant from 118MHz that the probability of
interference is equivalent to...a blue moon...or a logical debate on usenet.
>
> But maybe you are happy to disregard reports of demonstrated
> interference in favour of hypothetical rejection capabilities.
Not really. I took note of the fact that Boeing assiduously investigated
*every* case and in *no* case could the claimed/suspected interference
be repeated under controlled lab conditions.
Gee.
>
> Maybe you don't understand the limitations of the study - passenger
> use on *transport* category aeroplanes.
This thread started with some guy (a passenger) being arrested for
"endangering" an aircraft - presumably a transport, since it was
transporting the aforementioned passenger.
>
>> (the safety margin for GSM was calculated as 47dB)
>
> This has only limited relevance.
True (lol). 3dB would be relevant...
>
>
> I think you don't understand how these gadgets work.
What do you mean by "these gadgets"?
For a start, signals on a computer bus are effectively baseband. That
means that they spread frequencies all over the spectrum *up to* the
clock frequency and beyond.
In contrast, GSM operates in a band and any noise/crossover is limited
to sub-bands within that band.
>
>>> Thus, "do *not*
>>> interfere with aircraft navigation systems" would seem to be somewhat
>>> of an overstatement. Interference with VOR has been reported quite a
>>> few times.
>> Do you have a reference?
>
> I told you that I've seen it myself.
EM radiation is invisible.
> Beyond that, its been in the
> crash comics.
Huh?
>
>>> The US FCC does prohibit the airborne use of a number of types of
>>> mobile phone in the air for spectrum management reasons, rather than
>>> air safety..
>> GPS?
>
> No, its for just for their cell phone system. The US FCC reckon that
> it ties up too many channels.
