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About Your Computer 1

Entry 2288, on 2023-08-28 at 19:26:49 (Rating 1, Computers)

I was recently visiting a client and realised that there were many really basic things about her computer and phone that she didn't understand, and that the same was likely the case for most users. Many of these things aren't necessary to know, but if you do know them it makes a bit of difference for problem solving, setting up new devices, and interacting with technical support. In addition, it's just good to have a basic understanding of devices you use, purely out of general interest.

The issue I mentioned above was to do with Bluetooth, so I thought I might start by discussing how devices (computers, phones, tablets) communicate with other devices and the internet. Note that this will be simplified and not necessarily 100% technically correct, so if any pedants out there see any errors, then assume that is deliberate to make the discussion easier to follow!

Note also, that I am going to discuss these primarily from the perspective of Apple devices, but most of what I say could be also be applied to PCs, Android devices, etc.

In this post I will discuss wireless communications. There are three main ways your devices talk wirelessly to the "outside world" (this could be to a web site on the other side of the world or a wireless earbud a meter away). These are Bluetooth, wifi, and cellular. Note that computers and tablets don't tend to have cellular (although they can), but phones always do.

The main difference between these is the range they work over, their speed, what type of devices they usually communicate with, and how much power they use. These different characteristics explain why we need three different wireless systems instead of just one to do everything.

First, Bluetooth which has the shortest range, is the slowest, but uses the least power. It is used to communicate with devices which are usually close and don't need to send or receive a lot of data quickly, like wireless keyboards and mice, and earbuds. I find this works reliably inside up to about 10 meters, although various versions of Bluetooth (you didn't think there'd be only one, did you?) are designed to theoretically work from 1 up to 100 meters.

Earbuds are very small, so their battery is limited, they are generally close to the device they are communicating with, and the amount of data they send is relatively low, making Bluetooth an ideal solution. A similar argument applies to keyboards and mice.

It's usually safe to leave Bluetooth switched on, because it uses very little power, and it is not a common security problem, partly because of its short range. Note that, if you switch it off, don't expect to be able to use your earbuds any longer (as happened to my client).

Bluetooth requires devices to be "paired", which tells the phone (for example) which earbud (or other device) to send the signal to (so you don't end up sending your music to your friend's earbud who might be sitting next to you). With Apple AirPods, it's just a matter of opening the case and confirming the connection, but with some other devices, from not so user-friendly companies, it can be more complicated. You should only need to do this once, though.

By the way, if you were wondering about the origin of the name, it is the name of a Scandinavian tenth-century king, Harald Bluetooth, who united various tribes into one kingdom. One of the main reasons for creating Bluetooth was to merge all the earlier incompatible methods of communicating into one.

The next wireless system is wifi, which is generally used to connect a device to the internet. It has a longer range than Bluetooth, is much faster, but uses more power too. There is also a version, "Direct Wifi" which connects two devices together (like Bluetooth) but it is not widely used, because Bluetooth is so much more power efficient. You might see it in some printers and similar devices, though.

Wifi theoretically works up to 100 meters (you might see your neighbour's wifi in your list of possible connections), but this depends very much on the environment. Thick walls, sources of interference, etc, reduce this a lot. You can communicate with web sites thousands of kilometers away because your computer communicates, using wifi, to your wireless modem (or more technically correct, router) and that in turn sends that signal to the whole world over copper cables or fibre optic networks.

When connecting through wifi you usually have to provide a password, but your device will usually remember this and connect automatically with the stored password in the future. Some public wifi doens't need a password, but might ask for your email address, etc. Be cautious about these. You might want to consider a VPN (not discussed in this post, sorry) to ensure you are not being spied on, although this is unusual.

There are numerous wifi versions, with varying speeds and ranges, so more modern computers and modems might offer much better speeds than older ones. But note that internet speeds are only as good as the weakest link in the chain, so having a fast wifi connection is wasted if you have a slow link to the internet beyond the wifi connection, or you are accessing a web site in a country with poor internal speeds, or where the link between your country and the other one is slow.

Here in New Zealand, most people are now on "fibre" where the signal is transmitted by light down a glass fibre instead of electrically over a copper cable, and this tends to be fast and reliable (theoretically, at least), but note that we have a limited number of connections to other countries, so this can be a bottleneck.

Unlike Bluetooth, wifi does not have an interesting story behind its name. It is sometimes suggested it stands for "wireless fidelity" in a similar way to hifi meaning high fidelity (generally applied to audio equipment) but that isn't true, and wifi appears to stand for nothing in particular, although surely the "wi" part has something to do with wireless! Also note that the official spelling is "Wi-Fi", but I tend to use wifi because its neater and easier.

Finally there is cellular. This has the longest range, moderate speed, and is moderately power efficient. It is the system your cell phone uses to communicate. The phone communicates with the nearest (usually) cell tower and they all talk together to connect one phone to another, or your phone to the internet, usually through a cable or maybe a microwave radio link which handles the signal after it reaches the tower.

There are many cell towers and they can work up to a distance of 70 kilometers, although in areas where there might be a lot of phones the load is shared between towers which might be 2 or 3 kilometers apart, or even less than a kilometer in the middle of cities. The area each tower covers is called a cell, which is the reason the network is called "cellular". In many cases, your phone can see many towers (or cell sites) and it decides which to use based on signal strength and how busy that site is.

Ideally cellular covers the whole country, although it is common for there to be spots in remote areas where there is no coverage. To get truly universal coverage, satellite systems can be used, most recently StarLink, but that is not a common technology yet, and I'm not covering it here.

Note that smartphones can also connect through wifi, and if you have that option available you should generally use it, because it should be faster, cheaper, and more reliable. When you walk out of range of the wifi modem the phone should automatically switch back to the cellular network.

Smartphones usually offer a feature called "personal hotspot" or "tethering" where the cell phone can communicate with the cellular system and make that access available to other devices, like a computer which doesn't have cellular itself, through wifi. It effectively becomes a wifi modem you can use anywhere. This is great, except it can be expensive, depending on your plan, and some cell phone service providers also charge extra to even enable it.

While we are on the subject of data charges, let's briefly talk about that. When you connect your earbud to your phone through Bluetooth it only involves stuff you own so it is free. But when you connect to the internet through wifi the signal is sent onto a network owned by a service provider, and they will charge you for that. The same applies when you connect over cellular (for either internet data, text, or voice). Note that fibre or copper cable internet is usually charged separately from cellular, even if you use the same company for both, although there is usually a discount in this case.

So those are the main wireless communications options your devices might use. Just to finish I should mention that desktop computers, TVs, and other devices which are not intended to be mobile, often have a cable connection as well. This is called "ethernet" and in that case you can connect a cable between the device and your modem. Most modems have 4 ports to plug this sort of device into, but you can connect a much larger number by using ethernet switches or hubs.

I'm not going into details on this here, either, but if you can use a cable I usually recommend doing it, because it is the most reliable and usually the fastest method, plus each device has its own cable going back to the modem, instead of having to share the wifi with other devices which reduces the amount of data each device gets. I have all my permanent devices connected this way, through about 10 switches using cables I crawled under the house to fit, so this might not suit everyone!

So that's my summary of some of the tech behind how your devices communicate. In future articles I will cover many other subjects. If you have any suggestions leave a comment. I hope you found this useful!

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