How does cell phones work?

  • Thread starter anmolnanda
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  • #1
anmolnanda
20
0
i mean when data is sent from the network tower to the cell phone,can the data be detected by any other device?can the wave be concentrated in a particular direction(particular device) specifically...
 

Answers and Replies

  • #2
caffenta
144
0
Not really the right forum, but here goes:

Every single device in the area detects the signal. The multiplexing (the ability to have multiple conversations in the same signal) can be done in multiple ways. 2 common examples are Code-Division Multiple Access (CDMA) and Time-Division Multiple Access (TDMA). There are others. Usually, there is some kind of encryption built in so that you cannot eavesdrop on another conversation, or use a network without being a subscriber.

Microwaves and millimeter waves are fairly directional. The design of the antenna has a big impact. You can have tower-to-tower links over fairly large distances. However, targeting a single device would be impractical and not more secure than broadcasting over an area with encryption.
 
  • #3
sheaf
220
7
Yes, the antennas on the tower are designed with a particular "gain pattern". This means that they can concentrate the RF energy in a particular direction. For example, some cells have 3 sectors, at 120 degree intervals, each sector served from one tower by its own antenna with its maximum azimuthal gain pointed in the appropriate direction.
 
  • #4
anmolnanda
20
0
suppose there is a clone of a sim card in another area..so how is the tower going to distinguish between them
 
  • #5
anmolnanda
20
0
@sheaf
i mean the data is sent to a particular direction not in all directions?
like if the device is in east data only travels east of tower not west but data cover a larger area in east right?
 
  • #6
bonker
11
0
@sheaf
i mean the data is sent to a particular direction not in all directions?
like if the device is in east data only travels east of tower not west but data cover a larger area in east right?

I read about this somewhere. Theoretically it is a great idea, steering the microwaves directly to the antenna is an efficient procedure. Steering the signal can be achieved using a phased array of antennas:

http://en.wikipedia.org/wiki/Phased_array

Thats how antimissile system radars work as well as directed audio systems.

The problem, as I reacall, was that the handset needs to fit in multiple antenas, which causes space problems. I'm pretty sure there are people working on this
 
  • #7
BrockLee
31
0
Lookup Motorola Bible and cellphonediagram.com ;)
 

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