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Why you need modulation?
It might be helpful to have a working definition of modulation before making a statement as to why it is needed. In fact, with an understanding of what modulation is, it will be obvious why it is included in electronic communications.Modulation is the "message" or the "intelligence" that is impressed on a radio frequency (RF) carrier. When we transmit a signal, we generate a carrier frequency, and then we modulate it. We "add" the message or the information we wish to transmit by modulating the carrier in some way. There are at least a dozen different modulation schemes ranging from simple to real head scratchers. They either modify the amplitude, the frequency or the phase of the carrier. Let's look at a few.The simplest modulation technique is taking the transmitted signal and turning it on and off. It is "keyed" to send a series of pulses. Morse code uses on-off keying. In this method of modulation, no modification of the RF carrier signal itself is made. It is simply switched on and off. (It could be looked at as amplitude modulation with the carrier either at zero amplitude or at "maximum" amplitude with nothing in between.) A series of pulses can be transmitted. With Morse code, a short "on" period will send a dot or "dit" out. If we extend the "on" period a bit, we can send a dash or "dah" out. Nothing real sophisticated here, but basic and effective communication. There are obvious limits to how fast information can be transmitted with this modulation scheme. (But don't tell the hams who still use it!)Most of us are familiar with AM radio. AM is amplitude modulation. The amplitude of the RF carrier is modified to modulate it. The amplitude of the modulating signal will determine the amount that the amplitude of the carrier is changed. (The volume of the modulation determines how much the amplitude of the carrier is changed. The frequency of the modulating signal determines the rate of change of the amplitude of the carrier. (The frequency of the modulation determines how fast the amplitude of the carrier is changed.). The frequency of the carrier is held constant through all this.How about FM? In frequency modulation, the amplitude of the carrier is constant. It's left alone. But the frequency of the RF carrier is changed. It is swung above and below where it sits (it's assigned center frequency) at a rate proportional to the frequency of the modulating signal, and at an amount proportional to the amplitude of the modulating signal. In FM single sideband, the carrier frequency and the frequencies above the carrier are transmitted and the frequencies below the carrier are suppressed (upper sideband transmission). Or the frequencies below the carrier are transmitted with the carrier and the upper frequencies are suppressed (lower sideband transmission). In conventional television, the video signal is single sideband, suppressed carrier. It's like "regular" upper sideband transmission except the carrier signal is suppressed. Sideband transmission "saves" space on the RF spectrum. And it works because we really don't need "all" of the FM signal to demodulate the signal at the receiver.Other forms of modulation become more complex. CDMA (code division multiple access), TDMA (time division multiple access) and other methods are used in cell phones to modulate the carrier so the digital data stream can be impressed on the carrier.Modulation is the addition of intelligence to a carrier signal. It's the message. Modulation is necessary because the point of communication is getting the message through.A Simple answer:Simply this... Any communications medium: e.g. Free space - radio waves, Air - Sound waves or radio waves, Optical Fibre - Light, Copper Wires Electrical Anergy (with frequency limits of the copper wire construction) is made for a certain type of signal. But if the signal we want to send is not compatible with the medium, then it does not travel well.Modulation changes the information we want to send from it's original form, into one that is more compatable with the medium we are trying to use.For example, your computer speaks digital over a TCP/IP LAN which requires CAT 5 or better rated cables,, but to connect to your internet service provider (ISP), you need to send the signal over the wires of the telephone company (made for voice tones). To make this connection, and ADSL modem (modulator/demodulator) is used to convert the data into audio tones, which pass over the telephone line, and at the far end are converted back to digital to join the service providers network. in the reverse direct the ISP does the same, and the signals are de-modulated, back to data for your network.Or in simple terms, Its about best use of the medium. Everything else is just a away of doing it. And there are a lot of possible ways to choose.
What are the advantages and disadvantages of phase modulation?
Advantage - 1. Phase modulation & demodulation is easy compared to Frequency modulation. 2. Phase modulator is used in determining velocity of moving target by extracting Doppler information. Doppler information needs stable carrier which is possible in phase modulation but not in frequency modulation. Disadvantage - 1. Phase ambiguity comes if we exceed its modulation index pi radian(180 degree). 2. we need frequency multiplier to increase phase modulation index. Visit my website http://harshit.org
What are the goals for digital modulation?
Simply put, digital modulation is designed to maximize the amount of data we can put through a system per unit of time while maintaining the integrity of that data. Those are the two primary goals.
How does the circuit of a collector modulation work?
The output stage of the transmitter is a high power frequency class C amplifier. Class C amplifiers conduct for only a portion of the positive half cycle of their input signal. The collector current pulses cause the tuned circuit to oscillate or ring at the desired output frequency. The tuned circuit, therefore, reproduces the negative portion of the carrier signal. The modulator is a linear power amplifier that takes the low level modulating signal and amplifies it to a high power level. The modulating output signal is coupled through modulation transformer T1 to the class C amplifier. The secondary winding of the modulation transformer is connected in series with the collector supply voltage Vcc of the class C amplifier. Read more: [http://www.daenotes.com/electronics/communication-system/am-modulators#ixzz2R69fAPRC http://www.daenotes.com/electronics/communication-system/am-modulators#ixzz2R69fAPRC]
Why do you use modulation in gsm?
in the case of communication through gsm technology we transmit our voice frequency to somewhere from the origin. normally human voice frequency lays between 300-3400khz. if all the people tends to transmit their voice, the signal wil be distroyed due to interference. also theoretically it need a very long antenna to transmit a low frequency. therefore it is necessary to modulate each and every signal to a high frequency carrier to transmit without any interference and make possible communication mohamed zawahir +94772260383
What is tone modulation?
Tone modulation through of modulating a carrier frequency using the charactoristics of a sound, its the method used for telephone
What is modulation in data communication?
Data modulation is a method of Electronic packing of data. In Data communication data is transmitted through a process which is called "Data Modulation".
How are side bands produced?
Sidebands are produced when a carrier signal is modulated, typically through amplitude modulation (AM) or frequency modulation (FM). In AM, variations in the amplitude of the carrier signal create additional frequency components above and below the carrier frequency, known as sidebands. In FM, changes in the frequency of the carrier induce sidebands at varying distances from the carrier frequency, depending on the modulation index. These sidebands contain the information being transmitted and are essential for demodulating the signal at the receiver.
How do you use RF carrier waves to transmet large amounts of data?
RF carrier waves are modulated with the data to be transmitted, typically using techniques like amplitude modulation, frequency modulation, or phase modulation. These modulated signals are then transmitted through the RF channel. To transmit large amounts of data, techniques like increasing the carrier frequency bandwidth, using more advanced modulation schemes, and implementing error correction coding can be employed to achieve higher data transmission rates over the RF carrier waves.
What is function of amplitude modulation?
Amplitude modulation (AM) is a method used in telecommunications to vary the strength (amplitude) of a carrier signal in proportion to the waveform being sent. This modulation technique allows the transmission of audio or data signals through changes in the amplitude of the carrier signal. AM is commonly used in broadcast radio to carry audio signals.
How velocity modulation is different from normal modulation?
As we know normal modulation is superimposing the wave with another carrier signal but the concept of velocity modulation is totally different, as The modulation in velocity of a beam of electrons or ions caused by passing the beam through a high-frequency electric field, as in a cavity resonator there is no concept of superimposition.
What is the significance of the delta f/f measurement in the context of frequency modulation?
The delta f/f measurement is important in frequency modulation because it indicates the extent of frequency deviation from the carrier signal. This measurement helps determine the amount of information that can be encoded and transmitted through the modulation process.
Why carrier signal has higher frequency than message signal?
Carrier signals have higher frequencies than message signals to effectively transmit information over long distances and through various media. The higher frequency allows for better modulation techniques, which help to reduce interference and increase the capacity for multiple signals to be transmitted simultaneously (multiplexing). Additionally, higher frequency signals can be more easily directed and are less susceptible to noise, ensuring clearer reception of the underlying message signal.
How do amplitude modulation and frequency modulation differ?
Amplitude modulation is where a constant carrier is modulated by the signal, so that the envelope of the carrier represents the signal. Frequency modulation is where a constant carrier is modulated by the signal, so that the frequency of the carrier represents the signal. Phase modulation is where a constant carrier is modulated by the signal, so that the phase angle of the carrier represents the carrier.
What is the Comparison of frequency modulation and amplitude modulation?
I will answer this in the simplest way I know in the application I use it in; this would be in audio applications. Amplitude modulation is modulation of a carrier source's loudness; Frequency modulation is modulation of a carrier source's pitch; and Phase modulation is modulation of a carrier source's duty cycle/symmetry/timbre. One can often notice that all 3 modulation types relate in some way with another in that when frequency rises and falls it typically makes it favorable for either a rise in loudness or timbre. The most analog way to understand it in nature is typically your small vowel sounds like "iiiiiiiiiiiiii" as in the American-English word 'easy' and 'eeeeeeeeeeee' as in 'edge' are easier to say with loudness at higher pitches; medium vowel sounds like 'uuuuuuuuuuu' as in 'Utter' or 'sOn' and 'aaaaaaaaaaaa' as in 'Awe' *chuckles* are easier to say with loudness at medium pitches; large vowel sounds like 'ooooooooooo' as in 'Oh' and 'uuuuuuuuuuuu' as in 'rUne' are easier to say with loudness at lower pitches. AM is often known as 'tremolo'; FM is often known as 'vibrato'; PM is often known as 'wow'; AM/FM is 'vibremelo' and fill in the blanks for the other sub-variants. Maikel Stellerfield
Can dc be modulated using ac carrier?
Yes, DC can be modulated using an AC carrier through a process called amplitude modulation (AM) or frequency modulation (FM). In this process, the DC signal is combined with an AC carrier wave to create a modulated signal that varies in amplitude or frequency based on the DC level. This technique is often used in communication systems to transmit information over long distances. However, the effectiveness and application depend on the specific use case and the characteristics of the signals involved.
What is a SSBSC signal?
Single Side Band Suppressed Carrier. This is a modification of AM (Amplitude Modulation) that both reduces required transmitter power and signal bandwidth. The carrier is first modulated by the signal the same as in ordinary AM, then is sent through a bandpass filter to remove one sideband and the carrier. To demodulate it and recover the original signal the receiver must reinsert the carrier using a BFO (Beat Frequency Oscillator) and Mixer.
