Tangentially… you could build a SFP module that uses a digital to analog converter, outputting the data as a range of voltages vs 1/0s. Hook it up to a speaker for terrible audio. Then listen to it with a microphone hooked up to an Analog to digital converter sfp module on the other end!
99% of the time when someone is talking about 'DAC' in a physical networking context it will be direct attached cable.
These types of cables are literally just copper wire connecting pins at either end. In comparison to fibre optics which require transceivers with their own logic and encoding circuitry within the SFP modules themselves.
Edit: I think this article is actually pretty harmful, I don't think people would normally think of networking as DAC/ADC...
> When it comes to copper cable communications, digital signals are converted as electric signals (analog signals).
The signal is still digital, it's not "analog" at all. Is data being read from your hard drive over a SATA cable "analog"?
You would call the chip that does the encoding for the physical medium the 'PHY' chip - not an DAC/ADC.
Fully agree. Thinking of network transceivers as digital to analog converters (DACs) is just as conflating as thinking of pulse width modulation (PWM) controllers as DACs. Analog to digital converters (ADCs) and DACs are referring to the fact the actual analog signal you input/output is the ground truth value of the data not that the digitally encoded signal is being sent in the real world on a wire. The difference is if the signal is distorted on the way to the other end of the cable it's still (within tolerances) decoded back to the same digital value despite the changes in the physical signal.
Tangentially… you could build a SFP module that uses a digital to analog converter, outputting the data as a range of voltages vs 1/0s. Hook it up to a speaker for terrible audio. Then listen to it with a microphone hooked up to an Analog to digital converter sfp module on the other end!