Analog VS Digital Signal in ROV SYSTEM

A signal is anything that changes with time and can be used to convey information.
In most electrical systems, including those in ROVs and AUVs. Signal usually take the form of fluctuating voltages or currents in metal wires. In optical fibers, the signals typically consist of changing light levels.

Many electronic sensors use analog signals to report an analog temperature sensor might generate 0.1 volts per degree Fahrenheit. If an output of 5.8 volts was measured from this sensor, and you knew the sensor generate 0.1volts per degree F, then you would know the temperature was 58F. Since temperature varies smoothly and continuously between different values, the output of this sensor would also vary smoothly and continuously.

Digital signals use 0 and 1 to represent it’s value. In reality they usually take the form of a particular voltage being present or absent on a wire, or of light being present or absent in an optical fiber. Because they are  so easily and naturally be switched between two distinct states: On an Off. That’s one reason there are so many digital electronic devices today. And even bigger impetus for the growing popularity of digital communication formats is that digital signals are much less susceptible than analog signal to communication errors. For this reason, digital communication is generally preferred over analog communication whenever possible.

But WHICH system is faster? Analog VS Digital
For another example both AM radio and old-school broadcast TV use a signal with a continuously variable wave height or amplitude to represent sounds or visuals these sorts of analog waves can be decoded or de-modulated fairly easily with diodes that can be relay actual data to a screen or a speaker. Even though digital has obvious advantages we live to a great extent in an analog world.

Digital signal processing doesn’t exist in nature. It was invented by humans who aimed to unify the process of computation.
When you perform transformations on a digital computer having some signal from real world as an input (say, sound or video), you need to:
1.       Encode analog data (amplitude/frequency or a stream of light) into its digital representation (ones and zeros).
2.      Perform computation, if you want the system faster you should choose a faster CPU. But most of the time people should balance cost, energy efficiency, heat generating by the CPU(GPU) or MCU, and work condition. A faster CPU with high heating do not work in real life most of the time.

3.      Decode the digital result into an approximation of analog data (show the video on the screen, play mp3 sounds etc.)

4. Additionally, delivery message via digital system is a longer process,  people call (IP)protocol , protocol is a package, generally speaking, computer use a protocol to delivery info. to another point, the digital shall double check it , decode, bra bra bra, then show it on the screen or background running, embed system usually have 7 layers (such as OSI model in windows system).  but analog is like a simple physics to physics delivery message. 
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Steps 1 and 3 are artificial. People often use embed system for robots nowadays, such as linux, window CE as robot’s control system.When choosing these systems as upper computer, they need time to process. and, if you think about it, unnecessary. You can capture the video, encode it and mirror it in a program - or you can use a lens. Analog computers solve problems as fast as physics allow them to. Digital ones are limited by their clock rate.
Analog computers are not faster than digital, at least not always. They also have some limitations of their own - like being well-suited only for a narrow class of problems. But they do have their advantages in cases where there is a natural way of producing results, by performing the transformation and observing the outcome instead of running an approximate discrete simulation. I must add that this simulation might be easier to perform, as Rupert Baines points out.
In cases when analog computers are faster, that has a lot to do with their specialization - they were made specifically for a certain class of tasks and their architecture corresponds to a certain physical process. Digital computers were made to be universal.

Up to a point. An analogue processor feeds input and receives output in real time which is a speed that digital processors have been unable to match in the past. So a flight time of a few minutes on an analogue simulator could take hours on a digital system.
We live in an analogue world, sooner or later almost every digital signal has to be converted. Most really sizeable systems these days use a combination of both

To compare this, an interesting American old man SV seeker told a very good story for his ROV using a webcam(digital system). I strongly suggest you take a look at this video.

Edit by Linsen