How exactly is digital radio different than analog radio?

ogansemoi

Member
Nov 18, 2022
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Even if the station is using a computer instead of a purely analog setup for transmission and broadcasting, what they’re broadcasting still has to be converted into analog VHF radio waves so that it can be transmitted wirelessly, just like how a smartphone might receive your words digitally but has to convert them into analog UHF radio waves to be sent out to the tower (and vice versa), there one is only way for sound or images or even text to be transmitted wirelessly over distances and that is via waves of electromagnetic radiation, which is why afaik in order for something digital to be transmitted it has to be through wires (DSL and dial up over telephone lines, broadband over television cables, or why all modern TVs need a box hooked up to television lines whereas back in the day you could wirelessly watch TV with antennae) or turned into radio waves. So, especially considering that most FM and AM “analog” radio stations also use computerized transmitters these days, what makes digital radio different?
 

Gray

Well-known member
afaik in order for something digital to be transmitted it has to be through wires
If that were the case, wif-fi wouldn't be much good 😉

You're right about the nature of electromagnetic radiation of course.
With DAB they bung the digits in with it (as they do with wi-fi).
Traditional radio just modulates the frequency (FM) or amplitude (AM) of the electromagnetic waves, with an analogue signal.
 
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daveh75

Well-known member
Jul 31, 2008
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Precisely why it seems eerily familiar.

Feels like a sock puppet account* rather than spam for avoidance of doubt.

*There's a "well-known member" who posts in exactly this manner, i.e huge blocks of text that are largely gibberish...
 

Vincent Kars

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Mar 6, 2021
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in order for something digital to be transmitted it has to be through wires
But how do they do that?
Indeed by using electrons.
Are they analog? Yes they are.
Do digital electrons exist? No.
So the signal send over a wire is analog by design, we don't have anything else. Evertthing on out planet is analog. Period.

Digital is using an analog signal in a weird way.
Normally we use absolute values, e.g. a cartridge of a turntable sending a signal to a phono stage. Any change in the signal will be translate in a change of the sound including a spike when the airco start up.

In case of digital we still use analog signals (there are no digital electrons) but instead of using the absolute value, we are looking for a marked change of state.
A transistor is open or closed, a magnetic field is N-S or S-N, a pit or a land (remember CDs?), etc.
All the time there is very marked change of state.
Conceptually this is represented by bits, a binary unit that can have only 2 values also conceptually represented by 0 and 1.
This is what makes digital so robust. We don’t use the absolute values, we use this marked change of state to detect our bits.
So digital signal over a wire is a block pulse. The signal rises sharply to e.g. 3 V and drops sharply to 0 V.
Of course in real live a block pulse don't exist.


This is how a block pulse might looks in real life.
If this would be interpreted as an analog signal (using the absolute value), this would be a disaster.
The over/under shoot, the rise/fall time, the ringing, etc., all would manifest themselves as distortion.
The moment our interpretation is digital (the electrons remains analog of course), we don’t have these problems.
Despite all the distortions, we can clearly detect the rise to approximately 100% and the fall to approximately 0% of the signal.
As long as we are able to detect this marked change of state accurately at the receiver, we will receive not only the right bits, but will also be able to reconstruct the signal.
This is why digital is to a large extend insensitive to noise and can be delivered all around the world without loss in accuracy.
 

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