amplitute_modulation

amplitute_modulation - MODULATION 1. What is modulation? 1....

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MODULATION
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1. What is modulation?
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Modulation is the process of putting information onto a high frequency carrier for transmission ( frequency translation). 1. What is modulation?
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Once this information is received, the low frequency information must be removed from the high frequency carrier. This process is known as “ Demodulation ”.
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2. What are the reasons for modulation?
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1. Frequency division multiplexing (To support multiple transmissions via a single channel ) To avoid interference 2. What are the reasons for modulation?
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f M 1 ( f ) 0 f M 2 ( f ) 0 f M ( f ) 0 f 1 f 2 Multiplexed signal +
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2. Practicality of Antennas Transmitting very low frequencies require antennas with miles in wavelength
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3.What are the Different of Modulation Methods?
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1. Analogue modulation - The modulating signal and carrier both are analogue signals Examples: Amplitude Modulation (AM) , Frequency Modulation (FM) , Phase Modulation (PM) 2. Pulse modulation - The modulating signal is an analogue signal but Carrier is a train of pulses Examples : Pulse amplitude modulation (PAM), Pulse width modulation (PWM), Pulse position modulation (PPM) 3. What are the Different of Modulation Methods?
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3. Digital to Analogue modulation - The modulating signal is a digital signal , but the carrier is an analogue signal. Examples: Amplitude Shift Keying (ASK), FSK, Phase Shift Keying (PSK) 4. Digital modulation - Examples: Pulse Code Modulation, Delta Modulation,Adaptive Delta Modulation 3.What are the Different of Modulation Methods?
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ANALOG AND DIGITAL ANALOG AND DIGITAL Analog-to-analog conversion is the representation of Analog-to-analog conversion is the representation of analog information by an analog signal. One may ask analog information by an analog signal. One may ask why we need to modulate an analog signal; it is why we need to modulate an analog signal; it is already analog. Modulation is needed if the medium is already analog. Modulation is needed if the medium is bandpass in nature or if only a bandpass channel is bandpass in nature or if only a bandpass channel is available to us. available to us. Amplitude Modulation Frequency Modulation Phase Modulation Topics discussed in this section: Topics discussed in this section:
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Figure Types of analog-to-analog modulation
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Figure Amplitude modulation
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The total bandwidth required for AM can be determined from the bandwidth of the audio signal: B AM = 2B. Note
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Figure AM band allocation
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The total bandwidth required for FM can be determined from the bandwidth of the audio signal: B FM = 2(1 + β)B. Note
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Figure Frequency modulation
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Figure FM band allocation
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Figure Phase modulation
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be determined from the bandwidth and maximum amplitude of the modulating signal: B PM = 2(1 + β)B. Note
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This note was uploaded on 01/20/2012 for the course EE 301 taught by Professor Ahmetçakar during the Spring '11 term at Gazi Üniversitesi.

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amplitute_modulation - MODULATION 1. What is modulation? 1....

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