- Or, Why phone calls cannot be made from planes without
PicoCell technology
-
- No one, with a knowledge of antenna technology could
subscribe to phone calls from planes, and here are some basic reasons why.
This is somewhat technical, but this needs to be shown why this is virtually
impossible. I'll attempt to simplify it.
-
- 1. ANTENNAS - All antennas are characterized by what
is known as a "lobe pattern." The lobe pattern or area the antenna
is designed to serve is a result of it's physical shape and other factors.
The best omni-directional antenna is that of the single element antenna,
or single dipole antenna such as is used on all cell phones. This has a
circular lobe pattern. Note that this is not the same antenna used on cell
towers.
-
- Directional antennas are widely used in TV and radio
to maximize a service area. A receive and transmit radio frequency (RF)
pattern of any directional antenna is a roughly eliptical shape, or egg
shape. An example are AM radio towers, which may use other towers near
them. These other towers can be grounded to act as reflectors and direct
service to a nearby city. The FCC determines when and where antenna directional
technology can be used, and by which stations. Reflecting antennas can
also be used to prevent interference with other stations.
-
- Cell tower antennas use a specially designed directional
antenna which incorporates a reflector. This reflector is carefully designed
to create a directed radiation pattern directed over a large 2 dimensional
area. These reflectors work very much like the reflector you see in a floodlight.
Directional antenna characteristics are what divides a geographic region
into cells. Any given antenna type has the same receive and transmit lobe
pattern.
-
- Today you can see that most all visible cell towers have
a triangular pattern of antennas. This clearly shows that the 360 degree
area around a cell tower is divided up into three groups of antennas, with
each group facing one of three directions. Each antenna group lobe pattern
slightly overlaps the other. The FCC determines the effective radiated
power in watts of any transmitter, including cell tower antennas. Therefore,
every watt must be used efficiently for best signal quality (such as it
is.) Cell tower antenna design dictates that only a VERY small amount of
RF is radiated vertically up into the air, as this is considered lost RF
energy.
-
- 2. AIRPLANES - An airplane is made of aluminum alloy.
It is NOT transparent RF frequencies, but instead acts as a shield. Sections
of the plane made of carbon composite will greatly attenutate or even stop
all cell phone signals, as this is also conductive material. Only when
a cell phone has "line of sight" with a cell tower, can a talk
connection take place. And such a talk connection can only take place THROUGH
A WINDOW ON THE PLANE, because the body of a plane cannot pass the signal
from a cell phone.
-
- 3. Cell tower antennas use power levels of 100 watts
or more and group of antennas can have power levels of 800 watts. However,
a pocket cell phone only transmits an RF signal of less than 1 watt, with
many phones transmitting just .4 watts. No phone call can be made until
the cell tower receives this tiny signal and establishes a channel with
the phone by assigning the phone a frequency to talk on. This basic procedure
takes place on both digital and analog cell phones. Only the older, bigger
bag phones can output up to 4 watts of power, which almost no one uses
anymore.
-
- In conclusion we have:
-
- A. A plane moving at more than 500 MPH
-
- B. Plane windows acting as small aperatures for a cell
phone RF signal. This forces the cell phone antenna to become highly directional,
but without any increase in gain. There is no gain because plane is not
a reflector or resonant cavity tuned to cell frequencies.
-
- C. The cell phone is rapidly moving past cell towers
that may or may not be in line with the side of the plane. If a tower happens
to be in line with the side of the plane when it turns, such a connection
will not last but few seconds, if at all.
-
- D. The pocket cell phone signal of less than 1 watt must
be received before the call can be placed.
-
- E. Cell antennas have a weak signal lobe above them,
making establishing a connection with a phone
- unlikely.
-
- So, how could a phone call be made ?
-
- The "911 - In Plane Sight" proves beyond a
doubt, that at least one windowless plane was used on the second tower.
Imagine the challenge of trying to make a cell phone call, from completely
shielded window-less plane ! Network video enlargements clearly show it
was armed with a missile which is clearly visible when it was launched.
The detailed phone dialogs we've read about from those that "called
from the plane" can only be fiction and theatre.
-
- Since we know the flights did depart from airports, these
same people could not be allowed to live to tell the story of the fictional
flight. If they did make phone calls, it might have been at gunpoint on
the ground somewhere. It's likely they all went to the bottom of the ocean
with their knowledge.
-
-
- Ted Twietmeyer is the founder of http://www.data4science.net
which explores charted and uncharted regions of science. The website both
encourages public participation, and also provides a way for the public
to participate in science projects.
-
-
- Comment
- Name Witheld From Seattle
- 8-24-4
-
- Dear Ted,
-
- I was reading your article on Rense.com on cell phones
in flight, yesterday I made 2 flights with a motorola i205 nextexl phone,
1st flight, I had my cell off and then turned it on I suspect a little
under 10,000 feet and well over 250 knots in a Boeing 737-400 and could
not get ANY signal while still over a major metro area (Seattle).
-
- 2nd flight same day I left my phone on during takeoff,
and before even reaching 3000, feet and slower than 250 knots( over the
San Francisco Bay area)( as there is a speed limit that close to a large
airport)like about the time the flaps were coming up the cell had lost
its signal.
-
- I know this is unscientific but if a newer phone (3 years)
since 911 can't maintain a lock I highly doubt a 2001 phone could maintain
a lock.
-
- Hang in there
-
-
-
- Comment
- From Kelsea
- 8-25-4
-
- It is possible that calls made from the hijacked planes
on 9/11 would have a better chance of getting through to 911 than a new
phone would in an emergency today.
-
- I worked in the marketing department of a US cell phone
company in 2001. At the time, Tri-Mode phones were standard. Tri-Mode phones
received 2 types of digital as well as analog signals. By the time the
company released its first digital only phones, many who previously enjoyed
using their cellphones upgraded to find that they were unable to get a
signal or maintain a connection. The following explains why:
-
- From "Will your cell phone reach 911?", Consumer
Reports, 2/2003
-
- When your phone is in digital mode, it can work only
with your home carrier (the company you use for service) for any call--including
those to 911--unless the home carrier has a roaming agreement with another
carrier. Phones that can work in both digital and analog modes give you
more options. Analog provides that safety net for emergency calling. Indeed,
the principal FCC regulation governing wireless 911 recognizes the importance
of the analog mode. The regulation, which took effect in 2000, says that
whenever a wireless phone dialing 911 in analog mode can't get through
via its home carrier, that phone must seek another signal, even if it's
from a competing carrier, to quickly establish a voice connection. The
FCC concedes its rule is only a small step toward improving 911 service.
Multinetwork phones, which are normally in a digital mode, aren't required
to switch to analog to make a 911 call. There are no regulations for digital-only
phones..."
-
- In other words, for phones trying to make 911 emergency
calls using analog, cell carriers were required to seek out the nearest
tower (even a competitors' tower if necessary) to quickly connect the call.
There were no such requirements for phones attempting to connect to 911
using a digital signal. This actually did make a phone with analog a better
bet for reaching 911. However, companies began phasing out analog, passively
at first, after the FCC lifted requirements that they maintain the analog
system in Fall of 2002.
-
- Among Consumer Reports conclusions:
-
- The FCC must ensure that digital phones are more compatible.
- The FCC voted last fall to phase out its requirement
that some wireless providers offer an analog backup signal. We think that
was a mistake because the agency did not also require companies to make
their digital technologies talk with one another. Simply allowing analog
to fade away removes the principal common wireless language. In the end,
you will have less assurance than you do now that your phone will get through
to 911.
-
- http://www.consumerreports.org/main/detailv2.jsp?CONTENT
%3C%3Ecnt_id=299615&FOLDER%3C%3Efolder_id=162691
-
- So attempting to make a call from a plane today using
a newer technology cell phone isn't really a fair comparison. The analog
system is patchier and discontinued in many places altogether; many phones
only offer access digital now anyway. On 911, the callers on the hijacked
craft were almost certainly off the digital network using a trimode (or
lower quality) phone. When digital couldn't get through, their phones switched
to analog which, at least in a 911 call, gave them a better chance of getting
through.
-
- This still doesn't clear up how calls were made at altitudes
over 8,000 ft (and possibly up to 30,000 ft).
- Thanks,
- Kelly
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