Wireless Fidelity

Conversion of data into bits

Text is converted into data through ASCII encoding.

The pixels in an images are separated into layers of red, green, and blue. Each pixel of each layer carries a specific shade of the color that can be represented in binary.

Voices are recorded as sound waves. The waves are sampled and converted from continuous to discrete values. The value at each time is stored as bits.

Transmission of signal

Signal generators encode signals I and Q with info that is transfered to a modulator. The modulator mixes I and Q together with an oscillating wave and generates a radio frequency signal to be propagated.

Radio Signal Itinerary

Radio signals are a type of electromagnetic (EM) waves which are created by self-inducing electric and magnetic fields. Electric fields (E) interact with moving and fixed charges. Magnetic fields (B) interact with moving charges only. Radio waves travel at the speed of light and are the lowest frequency of the EM spectrum. To prevent interference, the Spectrum Management and Telecommunications decides which device can use which frequency.

Modulation

Amplitude Modulation: amplitude variationin proportion to modulating signal.

Phase Modulation: phase changes in proportion to modulating signal.

Modulation is used to impress the digitized information onto radio waves to be transmitted. It produces a varying signal that is proportional in some way to the information being transmitted. One method of modulation is the Quadrature Amplitude Modulation (QAM). A combination of amplitude and phase modulation by mixing two sine waves that are 90 out of phase.

These waves can be modulated by changing the amplitude M of the resulting simple harmonic motion equation.

How fast these changes occur is known as the baud rate which can be converted to bits per second.

4-QAM a type of QAM with only four combinations: 00 10 11 01

Changing amplitude and phase corresponds to different points on the polar plot.

The Networking

The transmitted signal from the wireless adapter inside a laptop isreceived by the local wireless hub.At this point the data is on the Internet. When downloading occurs, this entire process is reversed.