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for example :

Sender: A cellular signal tower(Base Station(BS)) sends data(voice, GPRS, VOIP) to the cellphone. The sender will obviously have the carrier frequency and more power(voltage+current) to generate the carrier signal.

Receiver: A cell phone which receives the data signal (voice, GPRS, VOIP) from the BS. This requires less energy because the cell phone is receiving data.

I want to know, when the receiver sends data(voice,GPRS,VOIP) to the BS, how does it do this?

Does the cell phone generate it's own carrier signal?

If yes, then how can a 3.7 volt battery be available for 8-12 hours?

OR

The receiver's signal goes on to same carrier signal which is generated by the BS.

If yes, How? Does the carrier signal use refraction/reflation properties to send data back to BS?

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When a cell phone is sending, it generates its own carrier. The power for doing this comes from the cell phone's battery.

Batteries in a cell phone may last 12 hours, but that is not while transmitting. Depending on how "off" the cell phone is, it is only occasionally listening to the cell tower, and even less often sending anything to it. When not moving, it may send nothing at all for long periods of time.

The battery wouldn't last 12 hours with you continuously talking on the cell phone. That requires frequent transmitting, which uses a lot more power than just sitting there, even in standby mode listening for others to call it.

Transmitting power also depends on distance to the cell tower. Actually the phone doesn't measure distance, but the cell tower tells it how well the message was received. The phone cranks up the power as needed achieve whatever it considers a acceptable error rate.

Despite all that, the predominant energy drain on the battery can be illuminating the screen. If you want long life per charge, don't make the phone power up the screen.

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  • $\begingroup$ 1.I have seen cell phone tower are far away around 2-5 km in village. can cell phone generate carrier signal to send that long? 2.How does satellite phone works? they are more far away then normal cell phone. around (1000km) $\endgroup$ – editinit Nov 3 '15 at 21:00

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