Saturday, March 18, 2006

Cell Phone Reception Experimental Results.

For those of you who understand the implications of this experiment... "SHIT"

A few weeks ago I did an experiment with cell phone reception vs altitude. (Sorry I forgot to publish the results untill now.) I was testing the possibility for use of cell phones at verious altitudes...

First of all, I made sure that at the surface level I had good reception.

-Full bars at 500' AGL, (Above Ground Level)

Second, I also made sure that I had line of sight to at least one if not more cell phone towers throught the course of the experiment.

-Trust me, I am very aware of where the towers are!

As I climbed reception did indeed go down.

-By about 3000' AGL I was down to about 1 bar.

-I had absolutly no reception at 4500'AGL

-Several of us checked our phones and there was ablsulutly no inkling of sevicability at 5000'AGL for any brand of phone or cell phone service provider. This was the case even when holding the phone out the window for optimum reception and least iterferance from the Feraday Cage like properties of the aircraft.

I was only able to climb to 6000' AGL due to the service ceiling of the aircraft of 10,000' MSL and ground elevation of about 4000'MSL, but I think that it is very unlikely that we would have been able to re-aquire signal by climbing higher.

RESULTS: It is very unlikely that cellphones could be used above 5000' AGL.

If anyone has questions about my methods or sees flaws in my experiment, please comment. I will be able to retest if needed.


amateur.sophist said...

well fuck.

So if the reception was gone by about 3000' AGL, with towers in sight, we can deduce the line of sight distance to be about, what, 10,000' max? Which makes sense, considering a cell phone's transmitter is only a few watts of power- 5w peak, I think.

i know those things were low, but they probably had to be at least 20k right? Also, even if you did manage to connect with a tower, at 400mph you'd be picking up ad losing those towers pretty quick. (assuming, you know, you were at ground level).

well fuck.

Gnome said...

I feel like I'm missing half the story, however if for some reason you need a phone that works at high altitudes you should look into a sattelite phone.

One big factor in the range is that the cell sites have direction. Quite often phone companies will point and power their cell sites to get tight beams, for instance along streches of road/highway. This way instead of offering coverage to a wide area they offer it in a focused range and get a greater distance. This is prevelant in on highways as a means to stop people in cars jumping rapidly from tower to tower. It's not surprising that you'd lose signal above a tower in a relatively short distance since the provider would definately not have their antennas working to shoot a signal above them.

Anyway thinking back to when I used to work on all this junk, I can't remember any maps that were created for cell site range projection showing a radius larger than a couple miles, so 10,000 is probably a decent estimation.

Notorious said...

An airliner would probably be above 5000' with in the first 4-6 minutes after tackoff. On approch to landing they are about 5000'and lower for the last 3-10 minutes. This depends a lot on the particuar airspace that one is flying through... but should be a very good estimate.

I think it is very unlikely that the particular aircraft in question would have come down below 5000' before the last 2 minutes of ingress to their targets...and certainly wouldn't have been just as they where being taken over.

Then again, If I were to attemp that particular mission, I would have had grass stains on those planes the ass soon as possible. Maybe the "bad guys" were better than we give them credit.

For those confused...

catlin said...

hey so does holding your celly out the window count as scanning?