6-1 SSB Versus AM: Types of Sideband Signals Figure 6-1 shows a typical AM signal, which can be thought of as a DSB-FC (double-sideband, full-carrier) signal. Signal fading is less likely to occur. The following are the advantages of Standard Amplitude Modulation : 1. State the four main benefits of SSB over conventional AM. In practice, there will always be an offset, due to neither radio being exactly on frequency. a. For example, to 100% modulate a 100 watt carrier requires 50 watts of audio power (not 100 watts), which makes a total of 150 watts (not 200 watts). It is mathematically represented as below. Here is a list of advantages and disadvantages of FM and AM radio systems. My main beef for SSB is the 3khz frequency bandwidth of typical SSB transmissions, it’s just too narrow for decent music sound quality. Keep up the good work. Types of Amplitude Modulation (AM) – Advantages & Disadvantages Thus, from the above expression, it is clear that output voltage is a combination of modulating signal along with the DSB-SC signal. In fact, only one-third is modulation and each sideband contains one-sixth of the total power. 40 dB Signal to Noise Radio (SNR), It might also be useful to compare them to the previously generated AM signals: Listen to the simulated recordings below to see the effects of various Signal to Noise Ratios: 10 Hz is still too much of an error for listening to music. Answer: The main benefit of SSB signals is that the spectrum space they occupy is less than half of that of an AM signal. Here, even small tuning errors of ten Hz can cause the audio to “not sound right”. The second problem is drift. 10 dB Signal to Noise Radio (SNR) Another perhaps greater advantage of SSB is the 9dB (nearly 10x) advantage vs. AM. 3. Build an AM transmitter yourself and you’ll soon discover that is indeed the case. On SSB, there is no carrier. Types of Amplitude Modulation (AM) – Advantages & Disadvantages Thus, from the above expression, it is clear that output voltage is a combination of modulating signal along with the DSB-SC signal. A comparison of various amplitude modulation schemes (types of amplitude modulation) is provided here. You only need a couple of minutes to set up, and you should be ready to use it. This is not true with SSB. Advantages of SSB Transmission: 1 More effective utilization of the available frequency spectra. The occupied spectrum space otherwise BW is smaller than amplitude modulation & DSB signals. An AM signal with a SNR of 0 dB is almost impossible to listen to, while an SSB signal, while difficult, is intelligible. This means that there is more spectrum space conserved for other signals to be transmitted in the same frequency. I’ve created some simulated recordings of USB signals. The carrier source produces carrier signal. Single SideBand Suppressed Carrier (SSB-SC) Modulation. φSSB(t) * cos(Wc*t) = 1/2 m(t) + 1/2 cos(2*Wc*t) +/- 1/2 m^(t)*sin(2*Wc*t) The demodulated signal is passed through an LPF to remove unwanted SSB. Then, the receiver has 3dB less noise. This page covers advantages and disadvantages of QAM modulation technique.It mentions QAM advantages or benefits and QAM disadvantages or drawbacks.QAM are of many types viz. The Benefits of SSB By eliminating the duplicated side-band and carrier from transmission, the bandwidth has been reduced by half. The squeal frequency is the difference between the transmitter carrier frequencies. The formula for predicting bandwidth in a SSB system is BW = f m , where f m is the maximum modulating frequency used. 20 dB Signal to Noise Radio (SNR) The carrier is used in the demodulation (reconstruction of audio) of the signal by the receiver. With SSB, there is no transmitted carrer. So in the case of SSB, for 100% modulation, four times the power is available for the sideband as compared to AM, for a given total transmitter power. Single side band (SSB) is an amplitude modulation technique in which only one sideband (upper or lower) is transmitted and Double side band (DSB) is a modulation technique in which both the upper and lower sidebands are transmitted simultaneously. Let’s take a look at the spectrum of an AM signal (click on it to enlarge it): This has many advantages. On SSB, there is no carrier. Bandwidth or spectrum space occupied is lesser than AM and DSB signals. All the best. First, you have 6dB more power (well, legally it’s 3x for CB–12W vs. 4W–but the final transistors are typically capable of 4x (16W) ahem). AM transmitters are less complex . (Written) 18. Could I mention though, that a common error is to assume that half of the power in an AM signal is modulation. Definition: Single sideband modulation (SSB) is an amplitude modulation scheme in which only a single sideband is transmitted through the channel. Advantages of SSB over full carrier DSB wave The bandwidth requirement of the single sideband system is half than required by double sideband system. This post is about various Amplitude Modulation Techniques like-Conventional Amplitude Modulation (Conventional AM), Double Side Band- Supressed Carrier (DSB-SC), Single Sideband Supressed Carrier (SSB-SC) and Vestigial Sideband (VSB) amplitude modulation. As long as the carrier and sidebands fit within the receiver’s passband, the signal will be correctly demodulated. A 100% modulated signal would sound louder (less noise, better SNR). Calculate the gain of an amplifier in dB if the input to the amplifier is 20µV and the output to an amplifier is 600mV. To the left and right of the carrier are the lower and upper sidebands. SSB has been favored for years by amateurs and is now used extensively by other services. Besides SNR, there are additional advantages (and disadvantages) of SSB over AM that need to be considered to decide which is better and under what circumstances. More channel space is available. More channel space is available . Power can be saved. State the four main benefits of SSB over conventional AM. 1. Athens, Greece, Enjoyed your article. 20 dB Signal to Noise Radio (SNR) So the power advantage of SSB over AM is six-fold (7.8 dB), not the four-fold stated in your article (which in any case would be 6 dB, not the 12 dB stated, as we are talking about power, not voltage). Using the CB radio on either SSB or AM mode is the same process. The disadvantage of FM over AM is that high output power is needed. The carrier source produces carrier signal. Picked up a dusty Realistic TRC-453 AM/SSB CB Radio to complement the TRC-465. d. … For the case of 100% modulation, each has one quarter of the total transmitted power. The receiver must produce it’s own carrier (often referred to as the BFO or Beat Frequency Oscillator in older radios). Radio Wolverine’s music broadcasts show it can be done well. Some radios get around this by having a knob that can be turned to adjust the BFO in an analog fashion (often called fine tuning, etc). (see for example: http://www.angelfire.com/electronic/funwithtubes/Basics_06_Mod.html) I thought it would be interesting to also compare AM (Amplitude Modulation) vs SSB (Single Side Band) transmissions. Generally, SSB signals tend to propagate greater distances and exhibit more graceful degradation over distance than FM signals. First off since the carrier does not contain any useful power we can eliminate it from the power gain equation. 27. 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. Indicate the false statement regarding the advantages of SSB over double-sideband, full-carrier AM. The listed choices are: Frequency Modulation (FM), Single Side-Band (SSB), Digital Radio Mondiale (DRM), and Phase Modulation (PM). Ideally, the BFO frequency is exactly on the frequency of the missing carrier from the transmitted signal. The noise changes the amplitude of the envelope of AM in a random manner . • Describe the various types of SSB transmission. Indicate the false statement regarding the advantages of SSB over double sideband, full-carrier AM. Four times is equivalent to 12 dB, or two S units. The formula for predicting bandwidth in a SSB system is BW = f m , where f m is the maximum modulating frequency used. 2 Less subject to the effects of selective fading because their is no definite phase relationship between the upper and lower side bands and the carrier as there is in conventional AM. Transmission of more number of signals is allowed. A 10 watts RF SSB transmitter can reach a distance about few hundred miles away,whereas a same 10 watts AM transmitter might reach not more than 50 miles. I have a different take on this. SSB signals produce stronger signals that can reach greater distance more reliably. Low bandwidth d. … Higher percentage of power is in radiated intelligence. over a noisy path, sideband methods prove superior to AM and FM. For voice communications, this is not a serious problem. 3. Next is the spectrum of an SSB signal, USB (Upper Side Band) in this case (click on it to enlarge it): This station is transmitting on 13270 kHz. Indeed, for a 100% modulated AM transmission, the carrier consumes half of the transmitted power. Since I had a long talk yesterday night with my amateur friends about exactly this matter, your article was a gift ! The 50 watts of audio will create two 25 watt sidebands and in SSB, only one of those sidebands is transmitted, ie 25 watts, compared with 150 watts total power with AM. Another perhaps greater advantage of SSB is the 9dB (nearly 10x) advantage vs. AM. Single sideband or SSB transmission is the method where the carrier and one of the sidebands are suppressed and the information signal is impressed in the other sideband. SSB signals produce stronger signals that can reach greater distance more reliably. The Benefits of SSB By eliminating the duplicated side-band and carrier from transmission, the bandwidth has been reduced by half. Simplicity of modulation and demodulation is indeed the chief advantage of DSB-AM -- a DSB-AM signal can use a low level modulator and Class C amps or a high-level final stage modulator with Class C carrier drive, whereas a SSB or DSB-SC signal must be generated low-level with a doubly balanced modulator and amplified linearly, which requires more components and reduces amplifier efficiency. The advantages of DSB-SC are that power consumption is nominal, the power from the signal can be contained in four sidebands, and the bandwidth is double the amount in the signal. a. a) True b) False Answer: b Clarification: The disadvantage of FM over AM is that in frequency modulation large bandwidth is required. State the four main benefits of SSB over conventional AM. If two people are talking, you just hear one quieter and one louder, within the dynamic range of the respective communications channel. System is half than required by double sideband system is an amplitude &... 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