# Conceptual vs real world signal transmission [closed]

When data or information is sent through any medium, (be it through phone lines, cable, fiber optics or through empty space or some other means), is it volts, current of charges, 0s and 1s, codes, binaries, photons Or is it something else?

Thank you.

• What is the actual question buried in the wall of text? And we don't only send data as ones or zeroes, there are dozens of different encodings, like 16-level PAM to send 4 bits per symbol, or QAM64 to send 6 bits per symbol. Feb 20, 2021 at 20:18
• Yeah, your whole thing is based on wrong claims, and hence there's really not anything to answer here. Your understanding is incorrect, and bits aren't the same as physical states.
– mmmm
Feb 21, 2021 at 0:58
• If you really want to dig into it you'll need to take several signal processing classes to know what happens to signals in the presence of noise. Feb 22, 2021 at 20:27

However, the two states are represented, charge, no charge, volts, no volts, etc but rarely if ever + and -. That is how it is taught conceptually in a classroom to my knowledge from the very start and it is emphasized if you will.

No it isn't (or shouldn't be). Logic ONE and logic ZERO (or logic HI and logic LO) are not physical. They do not "represent" something as much as they map to each other. The reason ONE and ZERO are common is because we do math with it. You can't do that as conveniently if you use something else like HI and LO or + and -.

If + and - values were taught, off state of 0 volts would be having a different significance.

Because they aren't physical, you can't do what you just did here where you say you have +, -, and 0 Volts because they aren't even the same thing. The first two are logical abstractions, the third is a real phenomena. One maps to the other but you speak of them here as though they exist in the same space which they do not.

However, trinary logic is a thing. This is where you have three logical states (as opposed to just two in binary) which map to three real-world values.

The logical states might be named:

• ZERO
• ONE
• TWO

Or you might prefer them to be labelled

• -ONE

• ZERO

• +ONE

Each of the three states might be mapped to real world measurement ranges:

• 0V<$$\v\$$<1V
• 1V<$$\v\$$<2V
• 2V<$$\v\$$<3V

Or, maybe you want to map it bipolar voltages:

• -3V<$$\v\$$<-1V
• -1V<$$\v\$$<+1V
• +1V<$$\v\$$<+3V

But you still can't mix up abstract logical with real world values so you would never talk about ZERO, ONE, TWO, and voltages 2V<v<3V as group.

Would I be correct to say if that was an actual case in the real world, in an ideal oscilloscope one should see two dots only. one dot for + volt up (whatever the value may be) above the time axis in the direction of + volt axis and for 0 volts there will be a dot on time axis horizontal axis and of course nothing below or the left of each axis.

Both the verticle line and the horizontal line would be meaningless in discrete on and off of our conceptual values.

Because of what I just said above, this part is rather meaningless and needs to be reformulated. It was rather incoherent to begin with.

While in the classroom it is 1 and 0, in the real world we round it off and make it look like it is. And if someone comes along and says you can't send 0 volts as it would be the same as the microprocessor, the system as being turned off at least on the sending side, and the receiving side then receives lots of 0 volts guaranteed for sure, the disagreement would loudly become obvious. Mostly the side that says you can turn the sending system on and then send signals and no voltage is needed wins and proves it too. What am I missing, assuming I didn't lose anyone.

This paragraph is even more incoherent. I have no idea what you are trying to say here. Figure 1. RS232 waveform and voltage levels. Image credits: Rs232_oscilloscope_trace.jpg: Ktnbnderivative work: Samuel Tardieu (talk) - Rs232_oscilloscope_trace.jpg, CC SA 1.0, https://commons.wikimedia.org/w/index.php?curid=6101703.

The old RS232 protocol may help your understanding. In this case data was transmitted at low speeds over long distances. Because of the possibility of differences in ground potential between both ends the system use a dual-polarity signal.

• -3 to -15 V is logic '1'.
• +3 to +15 V is logic '0'.
• Anything in between is undefined.

To avoid problems with strings of 0s or 1s and to tell where one byte started and ended, a byte1 was preceeded by a start bit, 0, and ended with a stop bit, 1. This guaranteed that a transition would occur even if an all 0s or all 1s was transmitted.

Would ... an ideal oscilloscope one should see two dots only.

It would show a continuous line on an analog oscilloscope for the duration the signal stays at each level. A digital 'scope takes samples which could be presented as dots or joined by lines.

Both the verticle line and the horizontal line would be meaningless in discrete on and off of our conceptual values.

I don't understand this statement.

... you can't send 0 volts as it would be the same as the microprocessor, ... and the receiving side then receives lots of 0 volts ...

If that's going to be an issue then you use a signalling handshake similar to RS232's start bit. Alternatively you use a separate clock line to synchronise both ends.

• I understand everything you said and I know all of that. I understand why 0 and 1 are used, those two mathematical abstractions if you will instead of other abstractions. Or why on and off is not used although the 1 and 0 are related to it. Question: Is 0 volts the same as no-volt, and is no volt the same as off as in the sender is not even powered on? That is by the literal definition of what off means not by circuit definition or signal definition? Will talk about the duration aspect in the follow-up. I am allowed only so many characters here. Feb 22, 2021 at 1:23
• @Ali Sometimes you need to know if the sender is not powered. Sometimes you don't. When you don't, you can use "zero volts" as a state. Even when you do need to know you can use handshaking instead of providing a third state. Feb 22, 2021 at 2:49
• @Ali Zero volts means that the wires have a low impedance between them (e.g. have been connected together). That is not the same as off, which could be a high voltage, low voltage or anything in between depending on the circuit design. I read your edits but could not understand them, so I cannot comment on anything else. Feb 22, 2021 at 2:55
• @Ali, logical 0 is usually generated by an output stage transistor connecting the output to the ground rail. The actual voltage achieved will depend on the amount of current it has to sink. Similarly a logical 1 is generated by an output stage transistor connecting the output to V+. The actual voltage achieved will depend on the amount of current it has to source. Feb 22, 2021 at 7:36