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A Brief Introduction to Wireless Technology

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Before jumping into a discussion of wireless technology, it's helpful to understand the basic structure of this technology. In this section, we'll discuss the basics of what a frequency is, what affects its speed, and what the differences are between the various frequencies.

The basic thing to understand about wireless signals is that every signal operates at a certain frequency that is, the number of oscillations per time unit that the signal makes. More oscillations means higher frequency.

The number of cycles per second is measured in hertz (abbreviated Hz). Most measurements we care about when discussing wireless communications involve megahertz (MHz) or gigahertz (GHz). A signal with a frequency of 30MHz, for instance, oscillates 30 million times per second. A higher hertz rate means that the signal has a greater bandwidth because more information (Is and Os, represented by the waves) is included in the signal each second.

Frequencies are divided into discrete groups, called bands, based on their hertz rate thus, based on their carrying capacity.

Important Radio Frequency Wireless Bands are the following:

- Band Hertz

- High Frequency (HF) ЗУЗОМНz

- Very High Frequency (VHP) ЗОУЗООМНz

- Ultra High Frequency (UHF) 300MHzY3GHz

- Super High Frequency (SHF) ЗУЗОСНz

- Extremely High Frequency (EHF) ЗОУЗОООНz

The radio-frequency bands currently used most often are HF, VHP, and UHF, with the higher-frequency bands coming into greater use as the lower-capacity bands are either saturated or unable to carry the data loads mat newer wireless transmissions demand. For instance, a frequency that can easily handle textual dispatching information might have problems carrying real-time video. Because of their higher frequency, IR transmissions have greater carrying capacity than RF transmissions but have a much shorter range. Generally speaking, the higher the frequency, the greater the bandwidth and the shorter the distance it will travel.

Because of their limited bandwidth, bands below HF, low frequency (LF) and medium frequency (MF), are not suited to wireless data transmissions.

 

Text 9

 

I. Memorize the following words and word combinations:

1. loosely-twisted rope - слобосплетенный канат

2. tightly-wound rope - тугонатянутый канат

3. to bend - сгибать

4. stray electronic signal - блуждающий электронный сигнал

5. fading signal - затухающий сигнал

6. adversely - неблагоприятно

 

II. Answer the questions to the text in written form:

1. How does a signal's frequency impact its ability to transmit data?

11. What is the difference between interference and attennation?

 

III. Translate the text orally.

 

 


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