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Modulation
Modulation - In earlier times, the most widely used form of communication was a system based on the transmission of a continuous-wave (CW) signal. With this system, the signal was interrupted periodically (Morse code) to produce a coded message. The CW systems required tremendous training..
Amplitude Modulation
c . In amplitude modulation, the amplitude of the wave is varied duplicating faithfully the fluctuations of the message. At the receiver these variations are detected or demodulated i.e., the message is removed from the carrier. (Although the more precise terms are demodulation..
Amplitude Modulated Transmission
The amplitude-modulated band (AM band) contains the radio waves having frequency of less than 30 MHz or having wavelength of 10 m or more. The lower atmosphere is more or less transparent to radio waves. However, the ionosphere reflects back the radio waves. Thus, a signal emitted by an ..
Pulse-Code Modulation (PCM)
It translates the sampled amplitude data into a code. The code is transmitted as a succession of pulses and spaces. The system enjoys greater freedom from noise and interfering signals than is possible with most other pulse systems. This freedom arises from the fact that it is merely necessary to ..
Modems with reference to computers
A modem (a modulator/demodulator) lets you connect your computer to a standard telephone line so that you can transmit and receive electronically transmitted dat..
Need For Demodulation
The wireless signal consists of radio frequency (high frequency) carrier wave modulated by audio frequency (low frequency). The diaphragm of a telephone receiver or a loud speaker cannot vibrate with high frequency. Moreover, this frequency is beyond the audible range of human ..
Modems
The 'modem' is a contraction of the term modulator-demodulator. It is a conversion that facilitates the transmission and reception of the data over the public switched telephone network (PSTN). The data of interest may be digital signals generated by computers or service providers. In suc..
Basic Principles of Wireless Radio Communication
Let us now discuss the basic principles of wireless radio communications. We shall mainly concentrate on the principle of amplitude modulation and demodulation. The simplest scheme of wireless communication would be to convert the speech or music to be transmitted to electric signals usin..
Let us now discuss the basic principles of wireless radio communications. We shall mainly concentrate on the principle of amplitude modulation and demodulation. The simplest scheme of wireless communication would be to convert the speech or music to be transmitted to electric signals usin..How Modems Work?
When a modem first makes a connection, you will hear screeching sounds coming from the modem. These are digital signals coming from the computer to which you are connecting being modulated into audible sounds. The modem sends a higher-pitched tone to represent the digit 1 and a lower-pitc..
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