Amplitude Modulation-DSBSC, single sideband And vestigial sideband


 

 

 

Chapter

Topics

Page

Contents

2

List Of Figures

 

3

Chapter 1 Introduction

4

Chapter 2 Double Sideband Suppressed Carrier Modulation

8

Chapter 3 Single-sideband modulation

13

Chapter 4 Vestigial Sideband in Amplitude modulation

16

Chapter 5 Overview

20

Index

22

References

23

 

 

 

 

 

 

 

  1. Introduction   …………………………………………… 4

1.1            Modulation Techniques    …………………………………  4

1.1.1              Reasons of modulation    ……………………………… 4

1.2            Amplitude modulation   ……………………………………5

1.2.1              AM Waveforms     ………………………………………6

1.2.2              Frequency spectrum of an AM signal    ………………..7

1.2.3              Properties of the spectrum of an AM signal   ………….7

  1. Double Sideband Suppressed Carrier Modulation   ………8

2.1            Properties of DSB-SC Modulation     ………………………8

2.2            Frequency spectrum of a DSB–SC signal     ……………….9

2.3            DSB Modulation       ………………………………………..9

2.4            DSB Demodulation        ……………………………………10

2.5            Application       ……………………………………………..12

  1. Single-sideband modulation    ……………………………13

3.1            What is single sideband modulation      …………………….13

3.2            SSB modulator      …………………………………………..14

3.3            Uses of Single sideband    …………………………………..14

3.4            Advantages of  Single sideband modulation     ……………..15

3.5            Disadvantage of  Single sideband modulation     ……………15

  1. Vestigial Sideband in Amplitude modulation   ………….16

4.1            what is VSB-vestigial sideband in Amplitude modulation …16

4.2            VSB Modulator        …………………………………………17

4.3            Spectra in the VSB Transmitter and receiver    ………………18

4.4            Uses  of vestigial sideband      ………………………………18

4.5            Advantages of vestigial sideband      ………………………..18

4.6            Disadvantages of vestigial sideband     ………………………19

  1. Overview  ………………………………………………….20

5.1            Comparison of Amplitude Modulation Technique …………20

5.2            Application of Amplitude Modulation   ……………………20

5.3            Limitations of AM         ……………………………………..21

5.4            Conclusion                     ……………………………………..21

 

List Of Figure

 

Fig-1.1: Amplitude Modulation …………………………..5

Figure-1.2: Standard AM – System ………………………6

Fig-1.3: AM waveform ……………………………………6

Fig-1.4: Frequency spectrum of an AM signal ………………7

Fig-2.1: Frequency spectrum of a DSB–SC signal ………..9

Fig-2.2: DSBSC modulator ………………………………..9

Fig-2.3: DSBSC demodulator …………………………….10

Fig-2.4: Time–domain representation of the different signals obtained in the DSBSC            modulation–demodulation process ……………………….11

Fig-3.1: Block diagram of SSB ……………………………14

Fig-3.2: SSB Modulator ……………………………………14

Fig-4.1: VSB Modulator and demodulator …………………17

Fig-4.2: Amplitude response of a VSB filter ……………….17

Fig-4.3: Spectra of VSB transmitter and receiver ………….18

 

CHAPTER-1

Introduction

1.1 Modulation Techniques

Modulation[4] is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted.

In analog modulation, the modulation is applied continuously in response to the analog information signal. Common analog modulation techniques are:[1]

  • Angle modulation
    • Frequency modulation (FM): here the frequency of the carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal.
    • Phase modulation (PM): here the phase shift of the carrier signal is varied in accordance to the instantaneous amplitude of the modulating signal.

1.1.1 Reasons of modulation[3]

  • Match the signal to the channel characteristics and increase the efficiency of information    transmission. Example: radio communications.
  •  Shift the frequency band occupied by the message signal. Examples: radio and optical communications.
  • Reduce the relative bandwidth. Example: analog video recorder (VHS–VRC)
  • Separate the signals in the frequency domain. Example: radio broadcasting, cable television.
  • Less sensitivity to channel distortion. Example: FM may be processed by a nonlinear channel etc.

1.2 Amplitude modulation

Amplitude modulation [1]is a type of modulation where the amplitude of the carrier signal is varied in accordance with the information bearing signal. The envelope, or boundary, of the amplitude modulated signal embeds the information bearing signal.

The total power of the transmitted signal varies with the modulating signal, whereas the carrier power remains constant.

A nonlinear device is used to combine the carrier and the modulating signal to generate an amplitude modulated signal. The output of the nonlinear device consists of discrete upper and lower sidebands.

The output of a nonlinear device does not vary in direct proportion with the input.

Amplitude Modulation is abbreviated AM.

Fig-1.1: Amplitude Modulation

 

Figure-1.2: Standard AM – System

Figure 1 shows the block diagram of an AM modulation and demodulation system. The major blocks are the two multipliers and the low pass filter to remove the high frequency parts of the down-mixed signal.                                                                                 AM modulation simply means the shifting of a signal frequency to another (usually higher) frequency. The information, or better the content of the original (modulating) signal is transferred to another frequency, the carrier.                                 Frequency shifting is done by multiplication of two signal in the time domain. Multiplication in the time-domain correspondents with frequency shifting in the frequency (ω) domain.

1.2.1 AM Waveforms[3]

 

                                              Fig-1.3: AM waveform

 

1.2.2 Frequency spectrum of an AM signal[3]

 

Fig-1.4: Frequency spectrum of an AM signal

1.2.3 Properties of the spectrum of an AM signal[3]

 

 


CHAPTER:2

Double Sideband Suppressed Carrier Modulation

Double-sideband suppressed-carrier transmission (DSB-SC) [4] is a transmission in which-

(a) frequencies produced by amplitude modulation are symmetrically spaced above and below the carrier frequency and

(b) the carrier level is reduced to the lowest practical level, ideally completely suppressed.

In the double-sideband suppressed-carrier transmission (DSB-SC) modulation, unlike AM, the wave carrier is not transmitted; thus, a great percentage of power that is dedicated to it is distributed between the sidebands, which implies an increase of the cover in DSB-SC, compared to AM, for the same power used.

For double-sideband suppressed carrier (DSB-SC) modulation the amplitude is related to the message as follows:

A(t)=Ac(t) m(t)

Where A(t) is the instantaneous amplitude of the modulated carrier, and is a linear         function of the message signal m(t). A(t) is also known as the envelope of the       modulated signal.

DSB-SC transmission is a special case of Double-sideband reduced carrier transmission.

This is used for RDS (Radio Data System) because it is difficult to decouple.

 

2.1 Properties of DSB-SC Modulation

(a)  There is a 180 phase reversal at  the point where +A(t)=+m(t) goes negative. This is typical of DSB-SC modulation.

(b) The bandwidth of the DSB-SC signal is double that of the message signal, that is,  BWDSB-SC =2B (Hz).

(c)  The modulated signal is centered at the carrier frequency ωc with two identical sidebands (double-sideband) – the lower sideband (LSB) and the upper sideband (USB). Being identical, they both convey the same message component.

(d) The spectrum contains no isolated carrier. Thus the name suppressed carrier.

(e) The power in the modulated signal is contained in all four sidebands.

 

 

2.2 Frequency spectrum of a DSB–SC signal[3]

A DSB-SC wave s(t) is given by

Fig-2.1: Frequency spectrum of a DSB–SC signal

2.3 DSB Modulation

The DSBSC signal is simply obtained by multiplying the information signal with the carrier signal as shown in the modulator (or transmitter) block diagram shown below

gDSBSC(t) = m(t)×cos(wct)  Û  (1/2) [M(wwc) + M(w + wc)].

 

Figure-2.2

This signal  gDSBSC(t)  is a modulated signal that has its spectrum centered around  wc and  –wc . Therefore, this signal becomes a passband signal with frequency that is much larger than the maximum frequency in  m(t)  and can be transmitted using a relatively short antenna. Also, other similar information signals can be modulated using cosine functions with different frequencies from  wc  and therefore, will not overlap or interfere with this modulated signal when transmitted over the same channel like a air or a coaxial cable.

Note:

• Both upper and lower sidebands exist, consequently the transmission bandwidth BT=   2W was not reduced. Problem of wasted bandwidth still exists.

• The possibility of using an envelope detector is lost.

 

2.4 DSB Demodulation

The demodulation process of a DSBSC signal involves obtaining the original information signal or scaled version of it from the modulated signal. This can be done by multiplying the modulated signal with another carrier signal that has EXACTLY the same frequency and phase as the carrier signal in the modulator block as seen in the demodulator block diagram shown below. The amplitude of the two carrier signals in the modulator and demodulator are not important since they just affect the magnitude of the different intermediate signals and final output signal of the demodulator.

Figure-2.3

The signal labeled  e(t)  in the demodulator becomes

            e (t)  = gDSBSC(t)×cos(wct) = m(t)×cos2(wct)  =  (1/2) m(t) [1 + cos(2wct)]

= (1/2) m(t)  + (1/2) m(t) cos(2wct)

Û  (1/2) M(w) + (1/2) [M(w2wc) + M(w + 2wc)].

However, as seen in the FT of e(t), the original message signal (scaled by 1/2) is present but also other components with frequencies centered around  2wc  and  –2wc.  These components are undesired and must be removed fop us to get the message signal. This can be done using a LPF (a filter centered around zero frequency that permits low frequencies to pass and rejects high frequencies). The BW of the filter must be 2pB rad/s  (or B Hz) or possibly slightly higher (but not much higher that it will allow the high-frequency components around  2wc  and  –2wc to partially or completely pass).

Therefore, the output signal f(t) of the LPF will be

e (t)  = (1/2) m(t)     Û  (1/2) M(w).

This is simply a scaled version of the original transmitted signal that can be easily amplified to obtain the original signal exactly.

Fig-2.4: Time–domain representation of the different signals obtained in the DSBSC modulation–demodulation process.

2.5 Application[9]

– Analogue TV systems: to transmit color information.

– For transmitting stereo information in FM sound broadcast at VHF

– One important application of DSB is the transmission of color information in a TV signal.

– CB radio

– TV broadcasting

– Air traffic control radios

– Garage door opens keyless remotes

– DSB-SC is a technique used in electronic communication, most commonly for transmitting information via a radio carrier wave.

DSB-SC used in stereo transmission of FM radio.

– Two way radio communications.

 

 



 

 

CHAPTER-3

Single-sideband modulation (SSB) [3]:

SSB: This stands for single sideband. Transmission in which only one sideband is transmitted is called single-sideband transmission or SSB. Carrier and one sideband are completely suppressed. The best way of thinking of SSB modulation is to first consider an amplitude modulated signal. This will have two frequency-shifted copies of the modulated signal (the lower one is frequency-inverted) on either side of the remaining carrier wave. These are known as sidebands: either upper sideband (USB) or less commonly lower sideband (LSB).

3.1 What is single sideband modulation[3]?

Single sideband, SSB modulation is basically a derivative of amplitude modulation, AM. By removing some of the components of the ordinary AM signal it is possible to significantly improve its efficiency.

It is possible to see how an AM signal can be improved by looking at the spectrum of the signal. When a steady state carrier is modulated with an audio signal, for example a tone of 1 kHz, then two smaller signals are seen at frequencies 1 kHz above and below the main carrier.

If the steady state tones are replaced with audio like that efficiency with speech of music, these comprise many different frequencies and an audio spectrum with frequencies over a band of frequencies is seen. When modulated onto the carrier, these spectra are seen above and below the carrier.

It can be seen that if the top frequency that is modulated onto the carrier is 6 kHz, then the top spectra will extend to 6 kHz above and below the signal. In other words the bandwidth occupied by the AM signal is twice the maximum frequency of the signal that is used to modulated the carrier, i.e. it is twice the bandwidth of the audio signal to be carried.

Amplitude modulation is very inefficient from two points. The first is that it occupies twice the bandwidth of the maximum audio frequency, and the second is that it is inefficient in terms of the power used. The carrier is a steady state signal and in itself carries no information, only providing a reference for the demodulation process. Single sideband modulation improves the efficiency of the transmission by removing some unnecessary elements. In the first instance, the carrier is removed – it can be re-introduced in the receiver, and secondly one sideband is removed – both sidebands are mirror images of one another and the carry the same information. This leaves only one sideband – hence the name Single SideBand / SSB.

SSB is the predominant voice mode on shortwave radio other than shortwave broadcasting. Since the sidebands are mirror images, which sideband is used is a matter of convention. In amateur radio, LSB is traditionally used below 10 MHz and USB is used above 10 MHz.

 

 

Fig-3.1: Block diagram of SSB

3.2 SSB modulator[3]

Fig-3.2: SSB Modulator

Note:                                                                                                                      • Transmission bandwidth is BT = W

• SSB assures the optimum exploitation of transmitted power and transmission bandwidth among the CW modulation schemes.

3.3 Uses of Single sideband modulation[6]

Single sideband modulation is widely used in the HF portion, or short wave portion of the radio spectrum for two way radio communication. There are many users of single sideband modulation. Many users requiring two way radio communication will use single sideband and they range from marine applications, generally HF point to point transmissions, military as well as radio amateurs or radio hams.

Single sideband modulation is normally used for voice transmission, but technically it can be used for many other applications where two way radio communication using analogue signals is required.

3.4 Advantages of Single sideband modulation[6]

Single sideband modulation is often compared to AM, of which it is a derivative. It has several advantages for two way radio communication that more than outweigh the additional complexity required in the SSB receiver and SSB transmitter required for its reception and transmission.

  1. As the carrier is not transmitted, this enables a 50% reduction in transmitter power level for the same level of information carrying signal. [NB. for an AM transmission using 100% modulation, half of the power is used in the carrier and a total of half the power in the two sideband – each sideband has a quarter of the power.]
  2. As only one sideband is transmitted there is a further reduction in transmitter power.
  3. As only one sideband is transmitted the receiver bandwidth can be reduced by half. This improves the signal to noise ratio by a factor of two, i.e. 3 dB, because the narrower bandwidth used will allow through less noise and interference.

The summary of this is that SSB modulation offers a far more effective solution for two way radio communication because it provides a significant improvement in efficiency. SSB assures the optimum exploitation of transmitted power and transmission bandwidth among the CW modulation schemes.

3.5 Disadvantages of  Single sideband modulation [7]

Complex transmitter and receiver configurations are required and Hard to demodulate.

Amplitude modulation typically produces a modulated output signal that has twice the bandwidth of the modulating signal, with a significant power component at the center carrier frequency. Single-sideband modulation improves this, at the cost of extra complexity.

To produce an SSB signal, a filter removes one of the sidebands. Most often, the carrier is reduced (suppressed) or removed entirely. What remains still contains the entire information content of the AM signal, using substantially less bandwidth and power, but cannot now be demodulated by a simple envelope detector.


CHAPTER-4

 

Vestigial Sideband in AM

VSB[3]: This stands for Vestigial Sideband. It is a form is signal where one sideband is completely present, and the other sideband that has been only partly cut off or suppressed. To reduce the amount of spectrum used, one sideband is transmitted fully, whereas only the lower frequencies of the other are transmitted. The high frequencies can be later enhanced using filters.

4.1 what is VSB-vestigial sideband[3]?

 

VSB is a form of amplitude modulation intended to save bandwidth over regular AM. Let’s say we have a baseband signal that extends up to 1 MHz that we want to transmit using some form of amplitude modulation. Let’s say it also has to be compatible with a simple receiver using a diode AM detector. Our choices for amplitude modulation format would be single sideband suppressed carrier, double sideband suppressed carrier, plain old AM (double sideband with carrier) or vestigial sideband. Let’s consider the choices…

SSB/suppressed carrier – transmit bandwidth is the same as baseband bandwidth (= 1 MHz). This is clearly a good choice for minimizing bandwidth, but the problem is that we can’t detect it with a simple diode detector found in most consumer AM radios (and analog TV receivers) because it is transmitted with no carrier signal.

DSB/suppressed carrier – transmit bandwidth is twice the baseband bandwidth (= 2 x 1 MHz). Not best choice for saving bandwidth, plus it has the same detection problem that SSB has.

Plain old AM – transmit bandwidth is twice the baseband bandwidth (= 2 x 1 MHz), but it can be detected with the simple diode detector. Good choice for the receiver, not so good for bandwidth.

Vestigal sideband – here we start with the plain old AM signal and filter out part of one of the sidebands, say 50%. So coming out of the transmitter we have the carrier signal, one complete sideband, and part of the other. We have reduced the bandwidth of the signal compared to plain old AM; our bandwidth is now about 1.5 MHz rather than 2 MHz. And the best part is we can still detect the VSB signal using a simple diode detector. After all, the second sideband information is redundant. Then you would have a signal only 1 MHz wide and we could still detect it with a diode detector. The problem is that the more of the sideband we filter out, the more distortion we get from the detected waveform, so there is a practical limit to how much we can reduce the bandwidth of the VSB signal. It’s about 50% reduction of one sideband. VSB is used in television transmission to save RF spectrum space.

Remarks of VSB:

• Vestigial sideband of modulation where one sideband is transmitted, but just a trace, or vestige of the other sideband is transmitted

• A VSB signal always may be demodulated by an analog multiplier

• However, if the carrier is also transmitted then the VSB signal may be demodulated by an envelope detector.

4.2 VSB Modulator[3]

 

Fig-4.1: VSB Modulator and demodulator

Amplitude response of a VSB filter (Only positive-frequency side is shown)

Fig-4.2: Amplitude response of a VSB filter

For NTSC TV signal

• Video bandwidth: W = 4.5 MHz

• Bandwidth of vestigial sideband: fv = 1.25 MHz

• Transmission bandwidth: BT = 5.75 MHz instead of 9 MHz

4.3 Spectra in the VSB transmitter and receiver[3]

Fig-4.3: Spectra of VSB transmitter and receiver

Remark: Carrier is recovered by a carrier recovery circuit.

4.4 Uses of vestigial sideband[3]

1.      VSB modulation is used to transmit television (TV) Signal, where the waste majority of signal energy is in the low frequency Region. In TV broadcasting a sizable carrier is also transmitted to make the Demodulation possible with a simple envelope detector.

2.       An analog TV signal has a baseband bandwidth of about 4 MHz. Transmitting as plain old AM would require 8 MHz of spectrum. With VSB it is 6 MHz. Now we can fit 4 TV channels using VSB into the same spectrum space as 3 TV channels using regular AM.

 

4.5 Advantages

  1. VSB is a form of amplitude modulation intended to save bandwidth over regular AM. Portions of one of the redundant sidebands are removed to form a vestigial sidebandsignal.
    1. The actual information is transmitted in the sidebands, rather than the carrier; both sidebands carry the same information. Because LSB and USB are essentially mirror images of each other, one can be discarded or used for a second channel or for diagnostic purposes.

 

4.6 Disadvantages

VSB transmission is similar to single-sideband (SSB) transmission, in which one of the sidebands is completely removed. In VSB transmission, however, the second sideband is not completely removed, but is filtered to remove all but the desired range of frequencies.


CHAPTER:5

Overview

5.1 Comparison of Amplitude Modulation Technique

Having studied the characteristics of the different forms of amplitude modulation techniques , we are now in a position to compare their practical merits:

In standard AM systems the sidebands are transmitted in full, accompanied by the carrier. Accordingly, demodulation is accomplished simply by using an envelope detector or square-law detector. On the other hand, in suppressed carrier systems the receiver is more complex because additional circuitry must be provided for the purpose of carrier recovery. It is for this reason we find that in commercial AM radio broadcast systems which involve one transmitter and numerous receivers, standard Am is used in preference to DSBSC or SSB modulation.

Supressed-carrier modulation system have an advantages over standard AM system in that they require much less power to transmit the same amount of information, which makes the transmitter for such a systems less expensive than those required for standard AM. Suppressed-carrier systems are therefore well-suited for point-to-point communication involving one transmitter and one receiver., which would justify the use of increased receiver complexity.

Single-sideband modulation requires the minimum transmitter power and minimum transmission bandwidth possible for conveying a message signal fron one point to another. Where vestigial sideband required a transmission bandwidth that is intermidate between that required for SSB and DSBSC modulation.

DSBSC modulation, SSB modulation, VSB modulation are the example of linear modulation.

 

5.2 Application[10]

Amplitude modulation is one way to carry information on a carrier, such as a radio signal, the other is FM (Frequency Modulation). While FM offers greater clarity for audio, and the higher frequencies that FM use offer a wider bandwidth, allowing for more information to be transmitted, one application where FM and digital are not suitable are Aviation communication, which to this day still use AM analogue. This is because weaker signals can be heard over stronger, closer ones with AM, allowing for emergency transmissions to have more chance of being heard over other traffic. Also, AM uses a narrower bandwidth than FM, allowing more users in a smaller space. This is important for the lower frequencies of Radio, where space is at a premium (ie shortwave bands).

 

5.3 Limitations of AM[5]

The limitation on AM fidelity comes from current receiver design. Moreover, to fit more transmitters on the AM broadcast band in the United States maximum, transmitted audio bandwidth is limited to 10.2 kHz by a National Radio Systems Committee (NRSC) standard adopted by the FCC in June 1989, resulting in a channel occupied bandwidth of 20.4 kHz. The former audio limitation was 15 kHz resulting in a channel occupied bandwidth of 30 kHz.

AM radio signals can be severely disrupted in large urban centres by metal structures, tall buildings and sources of radio frequency interference (RFI) and electrical noise, such as electrical motors, fluorescent lights, or lightning. As a result, AM radio in many countries has lost its dominance as a music broadcasting service, and in many cities is now relegated to news, sports, religious and talk radio stations. Some musical genres – particularly country, oldies, nostalgia and ethnic/world music – survive on AM, especially in areas where FM frequencies are in short supply or in thinly populated or mountainous areas where FM coverage is poor.


5.4 Conclusion

Although amplitude modulation is used since the first days of the 20th  century, it is still very popular. The advantages of AM are the easy and cheap way of realization and the little consumption of bandwidth. The disadvantages are the poor signal to noise ratio and the proneness to amplitude distortions.

An important part of amplitude modulation is the measuring of the modulation depth m. The modulation depth can be either determined by directly obtaining the ratio of the modulating and the carrier signal or to obtain the modulation depth via a trapezium display. The trapezium display is more exactly, because the modulation depth is directly readable from the oscilloscope’s screen.

Linear modulation is very necessary to obtain a not interfered signal at the receiver. In amplitude modulation, the sidebands contain the signal. The power in the sidebands is the only useful power. The power carrier by the side bands is only 33.3% even when there is 100% modulation. If modulation is 50%, then power carried by the sidebands is 11.1%. Clearly, the useful power is small. So, the amplitude modulation has low efficiency.

 

REFERENCES


[1]. http://www.tech-faq.com/modulation.html

[2].http://www.bookrags.com/research/amplitude-modulation-woi/Amplitude_modulation

[3]. http://www.mit.bme.hu/eng/research/chaos/chaos_link/…/eie331_04am.pdf

[4]. http://en.wikipedia.org/wiki/Modulation

[5].http://en.wikipedia.org/wiki/Sideband

[6].http://www.electronics-radio.com/articles/radio/modulation/single-sideband/ssb-basics.php

[7]. http://www.g3vre.org.uk/ssb.asp

[8]. http:/www.dbecker.desites/defaultfilesam.pdf

[9]. http://wiki.answers.com/Q/What_are_the_applications_of_DSB-SC_modulation

[10].http://wiki.answers.com/Q/What_are_the_applications_of_amplitude_modulation

[11].An introduction to ANALOG & DIGITAL COMMUNICATIONS-Simon Haykin

 

 

 

 

 

 

 

 

 


A

Amplitude modulation,2 audio signals,3     alternator,3                  audio fidelity,9      amateur radio,11

B

Broadcasting,3    Bandwidth,4                 Band,8

C

Carrier-                         Carrier signal,2,11     Communication,9,12    continuous radio wave,3 complexity,14

D

Discrete,2          demodulated,3,14  derivative,11              DSB-SC,9

E

Envelope,2,16   electromagnetic,3 efficiency,11

F

Frequency-              frequency modulation (FM),2 Frequency spectrum,7          Frequency shifting,5        Radio frequency,12        filter,14

H

high-frequency,3

I

Interference,3,9 inverted,11

L

Long wave,8        Lower Sideband,11.13  Limitations-           AM,9

M

Modulation,2        Modulation index,6    Message signal,6        Medium Wave,8    modulator-  SSB,12

N

Nonlinear,2

O

Overmodulated,6 Oscillator,12

P

Proportion,2                    phase modulation (PM),4 predominant,11

R

Radiation,3            receiver,12          reception,14         reduction,14

S

Sidebands,2                  Single-tone,8             Sinusoidal carrier,4 steady state,11 sensitivity,4                    Short wave,9,11                      SSB,9,11 suppressed,11,13,15 spectrum,11

T

Transmitted signal,2 Transmitter,11                 time-domain,5 transposer,12

U

Uppeer sideband,11,13

V

VSB,9,15

W

Wave,9

4 thoughts on “Amplitude Modulation-DSBSC, single sideband And vestigial sideband

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