Why Do Some Media Propagate Only Analogue Signals?

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In summary: Yeah that's great thanks, that's pieced together some of my misunderstandings. I have done some work already as regards modulation (amplitude-shift keying, frequency-shift keying and phase-shift keying) so I know see where all this fits together. Thanks for your time.
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adzo
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Hi, I hope this is the right forum.

I'm a computer science student and at the moment I'm a little confused with some basic theory regarding signals.

I am told that some media (such as fibre optics and other forms of unguided media e.g. microwave) only propagate analogue signals. Yet, guided media such as coaxial and twisted pair can transmit digital.

I feel that my course lecturer is attempting to hide some of the detail of this from us to avoid confusion, however, it is only confusing me more. Could someone please explain to me exactly why some media only propagate analogue signals.

Thanks.
 
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All physical media use analog signals to transmit information. The encoding can be digital, but the physical signal will always be analog in nature.

The difference between the transmission of digital and analog content is in the encoding and decoding of the information. An AM or FM radio broadcast uses analog RF signals to transmit analog sound information like voice and music. An XM satellite transmission uses digital encoding of the analog RF signals to transmit a digital representation of the sounds, which are then decoded by the terrestrial receivers and converted back into sounds.

For digital transmissions of analog information, an A/D converter is used on the original analog waveform, and the digital information is used to modulate the analog transmission waveform (using any of a variety of modulation schemes). At the receiver, the analog received waveform is demodulated back to the digital datastream, and then sent through a D/A converter to recover the original analog waveform. When the source and destination data are strictly digital (like Internet transmissions), the A/D and D/A steps are skipped, but the modulation of the physical analog carrier signal is still there. Even On/Off keying of a laser for fiber optics is using an analog waveform (light waves) to convey the digital information.

Makes more sense? Just pick up a good Communication Theory book and it will explain a lot about different modulation shemes that are used.
 
  • #3
Yeah that's great thanks, that's pieced together some of my misunderstandings. I have done some work already as regards modulation (amplitude-shift keying, frequency-shift keying and phase-shift keying) so I know see where all this fits together.

Thanks for your time.


berkeman said:
All physical media use analog signals to transmit information. The encoding can be digital, but the physical signal will always be analog in nature.

The difference between the transmission of digital and analog content is in the encoding and decoding of the information. An AM or FM radio broadcast uses analog RF signals to transmit analog sound information like voice and music. An XM satellite transmission uses digital encoding of the analog RF signals to transmit a digital representation of the sounds, which are then decoded by the terrestrial receivers and converted back into sounds.

For digital transmissions of analog information, an A/D converter is used on the original analog waveform, and the digital information is used to modulate the analog transmission waveform (using any of a variety of modulation schemes). At the receiver, the analog received waveform is demodulated back to the digital datastream, and then sent through a D/A converter to recover the original analog waveform. When the source and destination data are strictly digital (like Internet transmissions), the A/D and D/A steps are skipped, but the modulation of the physical analog carrier signal is still there. Even On/Off keying of a laser for fiber optics is using an analog waveform (light waves) to convey the digital information.

Makes more sense? Just pick up a good Communication Theory book and it will explain a lot about different modulation shemes that are used.
 

1. Why do some media only propagate analogue signals?

Some media only propagate analogue signals because they were designed to do so. In the early days of communication technology, analogue signals were the most common form of transmission. Many media, such as radio and television, were specifically designed to transmit and receive analogue signals, making it difficult and expensive to switch to digital technology.

2. What are the advantages of analogue signals?

One advantage of analogue signals is that they can transmit a continuous range of values, allowing for more precise and accurate communication. They are also less susceptible to interference and can travel longer distances without losing quality. Additionally, analogue systems are generally less complex and more affordable than digital systems.

3. Why has there been a shift towards digital signals in recent years?

Digital signals offer several advantages over analogue signals. They are less susceptible to noise and interference, which allows for clearer transmission and reception of data. Digital signals also have a higher bandwidth, meaning they can transmit more information in a shorter amount of time. Additionally, digital signals can be easily compressed and manipulated, making them more versatile for different types of media.

4. Are there any downsides to using analogue signals?

Although analogue signals have their advantages, they also have some downsides. They are more prone to degradation over long distances, meaning the quality of the signal can decrease as it travels. Analogue signals are also limited in the amount of information they can transmit, making them less efficient for complex data transmission.

5. Will analogue signals eventually become obsolete?

It is likely that analogue signals will eventually become obsolete as digital technology continues to advance. Many countries have already switched to digital broadcasting for television, and more industries are making the shift to digital communication. However, it may take some time for all media to completely phase out analogue signals, as there are still many systems and devices that rely on them.

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