The carrier is used in the demodulation (reconstruction of audio) of the signal by the receiver. 6. Generally, SSB signals tend to propagate greater distances and exhibit more graceful degradation over distance than FM signals. b. Transmitter circuits must be more stable, giving better reception . The listed choices are: Frequency Modulation (FM), Single Side-Band (SSB), Digital Radio Mondiale (DRM), and Phase Modulation (PM). While I’ve always preferred AM over SSB due to the audio quality, there’s no doubt that watt for watt, SSB results in a much better SNR for the listener. Analog Communications Multiple Choice Questions focuses on “Demodulation of SSB-SC”. If the transmitter is drifting around (or the receiver, or both), then the tuning knob will need to be continuously adjusted to bring the station back on frequency. a. For these simulations, I assumed that the typical modulation would be about 50%. Advantage SSB over AM AV2220 - Aircraft Communication Systems Chapter 1 8 9. Rather, they may be limited to a 10 Hz tuning step. SSB signals produce stronger signals that can reach greater distance more reliably. We use the power of both sidebands because that is the total useful signal power of an AM transmitter. State the four main benefits of SSB over conventional AM. It’s just that the argument used to get there is not correct, although widely promoted on the internet. 10 Hz is still too much of an error for listening to music. = m(t)*cos(Wc*t) +/- m^(t)*sin(Wc*t) Original signal is retrieved using coherent demodulation of SSB signals.φSSB(t) is multiplied with cos(Wc*t) and passed through low pass filter to get back theoriginal signal. • Describe the various types of SSB transmission. a. More channel space is available . • Explain the advantages of SSB over conventional AM transmission. (Written) 19. 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. These results suggest that homebrew 10 watt SSB transmitters would produce signals that could quite easily be received by listeners, in cases where an AM transmitter of the same power level would produce a weak signal with an SNR too low to be readily received. 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. Here, even small tuning errors of ten Hz can cause the audio to “not sound right”. Previously, in Signal to Noise Ratios, I compared how the SNR affects the quality of the received signal, with some simulated recordings at various Signal to Noise Ratios. 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. 5. 27. Then the only way out for SSB piracy is to mostly transmit voice, not music….Andy Yoder claims that the older tube rigs like Drakes actually have a better SSB sound because they aren’t tuned as narrowly as the modern digital logic rigs. 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. 10 dB Signal to Noise Radio (SNR) Could I mention though, that a common error is to assume that half of the power in an AM signal is modulation. SSB signals produce stronger signals that can reach greater distance more reliably. 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. Downsides are increased transmitter and receiver complexity and the fact that the transmitter has to have a linear output stage rather than a Class C output so is less efficient but the advantages are more than enough to justify this. This means we can have base-mobile communications–it’s so much clearer than AM, particularly when skip conditions are up. AM waves can travel a longer distance . With an AM signal, being “on frequency” is not important. 40 dB Signal to Noise Radio (SNR). In practice, there will always be an offset, due to neither radio being exactly on frequency. First off since the carrier does not contain any useful power we can eliminate it from the power gain equation. There are a few SSB broadcasters who seem to broadcast wider more full frequency SSB, Radio Wolverine comes to mind. 945. On SSB, there is no carrier. Each has the same amount of transmitted power. You only need a couple of minutes to set up, and you should be ready to use it. This would be a 9db increase in useful signal strength at the transmitter. 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. Four times is equivalent to 12 dB, or two S units. State the four main benefits of SSB over conventional AM. Victor. Low bandwidth In radio communications, single-sideband modulation (SSB) or single-sideband suppressed-carrier modulation (SSB-SC) is a type of modulation used to transmit information, such as an audio signal, by radio waves.A refinement of amplitude modulation, it uses transmitter power and bandwidth more efficiently. d. … a. over a noisy path, sideband methods prove superior to AM and FM. The carrier source produces carrier signal. Generally, SSB signals tend to propagate greater distances and exhibit more graceful degradation over distance than FM signals. Answer: The main benefit of SSB signals is that the spectrum space they occupy is less than half of that of an AM signal. While I’ve never been a huge fan of SSB (also referred to as Satan Side Band) for transmissions involving music, there’s no doubt that it does get out much better than AM. For the typical case of less than 100% modulation, each has less than a quarter. I’ve created some simulated recordings of USB signals. You can see the carrier on 9980 kHz, which consumes most of the transmitter power. AM transmitters are less complex . They are symmetrical about the carrier, and convey identical information. The audio quality is never quite as good–the circuitry has to hold the phase constant over a wide frequency range, and that always falls through a little bit, and the most noticeable factor is the slight difference in frequency causing Donald Duck sounding audio. The second problem is drift. The squeal frequency is the difference between the transmitter carrier frequencies. 1. Indeed, for a 100% modulated AM transmission, the carrier consumes half of the transmitted power. State the four main benefits of SSB over conventional AM. Let’s take a look at the spectrum of an AM signal (click on it to enlarge it): b. Transmitter circuits must be more stable, giving better reception. If we want to talk about SNR before detection at the distant receiver we would consider the reduction in bandwidth to one half the bandwidth needed for AM reception and a resulting reduction in the noise level by 3db. AM receivers are cost efficient . AM receivers are simple, detection is easy . How to Use SSB on CB Radio? I thought it would be interesting to also compare AM (Amplitude Modulation) vs SSB (Single Side Band) transmissions. At the receiver, there is also an additional 3 dB reduction in noise when using SSB, compared to AM, due to the two-fold reduction in bandwidth (slightly more than that). 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. Advantages of SSB over full carrier DSB wave. 20 dB Signal to Noise Radio (SNR) 20 dB Signal to Noise Radio (SNR) That 3db is now added to the SNR for a total of 12db SNR after detection for the SSB signal over AM. Higher percentage of power is in radiated intelligence. I think being able to use modern ham tranceiver equipment like the TS-870, Elecraft K3 or Flex radios, putting out a wide frequency sound with ESSB, and getting 4 times the power compared to AM transmitters makes for a compelling argument in favor of SSB transmissions, even for music. 1. 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. Power can be saved. CB radios are not difficult to operate. There is no carrier, and only one sideband is transmitted. Another perhaps greater advantage of SSB is the 9dB (nearly 10x) advantage vs. AM. Build an AM transmitter yourself and you’ll soon discover that is indeed the case. c. The signal is more noise-resistant. As you can imagine, this is significant. Percentage of power saving in SSB is 83.33%. High power signal can be transmitted. The receiver must produce it’s own carrier (often referred to as the BFO or Beat Frequency Oscillator in older radios). Therefore 400 watts divided by 50 watts equals a power gain of 8 times over AM. In the spectrum of AM wave, both the sidebands carry same amount of information which makes it meaningless to transmit same information in both the sidebands thus leading to power wastage. Advantages of SSB Transmission: 1 More effective utilization of the available frequency spectra. 27. 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. So the 12 dB advantage of SSB over AM you mentioned is not far from being correct. 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). 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