Computational problems, Yes, the Solution of computational problems, that can never be solved in a feasible time period by the existing supercomputers is the basic need of a Quantum computer. Quantum Computers use quantum-mechanical phenomena like Superposition and Entanglement to perform computation. Superposition refers to the presence of a quantum particle like an atom or a photon in two states simultaneously, exactly it is not simultaneous but it spins so quickly that it appears to be in both positions at the same time. Entanglement is a physical phenomenon in which a group of quantum particles, interact, share spatial proximity in such a way that their quantum states remain dependent on one other even if they get separated by larger distance. Such particles show wave-like properties, and when frequency and waveform of these particles become identical, they are said to be in Coherence. Coherence is a mandatory condition to perform computing. In a Quantum System, Superposi...
Cell phones are basically full-duplex radio transmitters and receivers, that are capable of transmitting and receiving radio signals using an antenna.
Full duplex means both the sender and recipient can talk at the same time but at different frequencies.
A cell phone uses two frequencies per call, one for speaking and one listening.
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| Digital Cell phone |
Radio waves occupy the range of 30 Hz to 300 GHz with wavelengths of 10000 km to 1 mm respectively in the electromagnetic spectrum.
Why Radio waves are used in communication?
Radio waves are transmitted easily through the air.
They don't cause damage to the human body.
These waves can be easily reflected to change their direction.
How cell phones work?
Your phone converts the radio waves into electrical signals and then into voice, similarly, voice is converted into electrical signals and then into radio waves.
Cell phones operate within the cells.
Each cell has a hexagonal shape.
A typical cell occupies an area of 26 square km with each side of about 3 km.
Total of 800 frequencies available
An analog cell phone uses 800 frequencies in 395 channels with two distinct frequencies each, one for speaking and one listening.
Each cell uses the seventh part of available frequencies.i.e.,(395/7), 56 voice channels (56 phones) can operate at a time.
No cell can use the frequencies of its adjacent cell.
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| Cell Network (critrim.blogspot.com) |
Each yellow cell can use the frequency of the other yellow cell, this frequency reuse allows cell phones to have incredible range.
395 channels have 790 frequencies and rest (832-790=42) frequencies are used in control channels.
Cells are monitored and controlled by base stations and base stations are controlled by central antennas.
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| Antenna |
This approach was used for Analog Cell phones which used to have smaller bands of available frequencies. However, the network standards (like 3G, 4G, 4G LTE) used today have broader bands, but the cellular approach remains the same.
Cell phones can switch cells using the Cellular approach (Frequency reuse) allowing cell phones to have incredible range.
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