A lot of people have this question when they're little: they need to pull a telephone line and signal follows the copper line to hear the sound across the street. But the phone is naked and there's no wire attached to it, and it's thousands of miles apart, and it's open and it's heard. How the hell did that happen
Many people simply understood that mobile phones sound and fly directly from air to each other's phones. That's not the right idea. The sound itself is the vibration of the air, which is not far away, and then decays after dozens of metres, and it is impossible to reach hundreds of thousands of kilometres. What's really passing through the air is not the sound of us talking, it's an invisible thing — radio waves。
We're going to break down a full-scale phone trip in white, one step at a time today, and you're going to understand that cell phones, wireless, are only the last few hundred metres, transmitted long distances, and that there's a big web of cylindrical fiber behind them。
First, you talk, your phone turns the sound into a digital code。
That's our voice when you talk to the microphone at the bottom of the trigger, and the acoustic vibrating drives the air. The microphone contains a tiny thin film that shakes with the sound and turns the air into a powerful and changing telecommunications signal。
But this is not a direct remote transmission. Cellular internal chips convert a continuously changing sound signal into a digital string of 0 and 1. Simplely understood, it's to take your voice into a series of digital codings, like a video compressed into a data package. Whether you speak mandarin, dialect, laughter, it's all a combination of zero and one。
Step two, cell phone antenna. Pack the digital code into a radio waveBase stationI don't know。
The radio frequency module in the mobile phone will load the string of 0 and 1 onto the radio wave and launch it through an inner antenna. Here's a reminder: radio waves don't fly directly from your phone to another phone a thousand miles away. Radio waves have a limited reach and are also blocked by buildings and mountains, leaving dozens of kilometres of signals too weak to recognize。
It will only fly to the base station closest to you, that is, the tower on the edge of the road, the tower on the top of the hill, which is typically hundreds of metres to a few kilometres away. The base station is like the first delivery station on the communications road, steadying this invisible radio signal and putting it in the airElectromagnetic waves, restore digital data packages to 0 and 1。
This is where the air wireless transmission ends. From the base station, the remaining distance is a thousand miles, not air, but fibre-optic cables buried in the ground and under the sea floor. Many people think that mobile phones are completely wireless and that the long-distance backbone is all fibre-optic, which is the biggest cognitive error for many。
Step 3: the fibre-optic trunk transmits the signal at high speed, and the operator's core network is responsible for the “directional route”。
Upon receipt of your voice data package, the base station passes fibre-optic to the operator's core network, which is the “brain” of the entire communications network. The first thing on the core network is to identify your cell phone number and find out where the cell phone is in the area and which base station。
Upon confirmation of location, the core network will open a temporary information channel to transport your voice data package across the city along the fibre-optic backbone. For example, in fujian, you call your friends and friends far from heilongjiang, and the signal is transmitted from a fibre-optic network all over the country. The speed of fibre-optic transmission is close to the speed of light and is extremely low, so we can barely feel the delay on the phone。
Step four, the base station near the other side, again via radio waves, sends the data pack to the other side's cell phone。
When the signal reaches the other side's city, it is sent to the base station close to the other side. The base station then packaged the digital information into a radio wave and launched it into the air. The antenna of the other phone received radio waves, the chips were decoded in reverse, the numbers of 0 and 1, were converted back to telecommunications and sent to the speaker. The horn shakes the air and restores the sound of your voice, so the other one can hear you。
The call is two-way, talking to each other, the whole process is reversed and the signal is sent back to your cell phone along this network. From time to time, a thousand miles of real-time dialogue has been achieved。
Here's the core design of cellular communication. The operator divides cities and villages into numerous small areas of hexagon, like beehive cells, each with a base station, which is called the cellular network. Each station is responsible only for its own small area. When you make a phone call while you're walking, you go from one block to another, you automatically switch to a new base station in the vicinity, and the call doesn't go off, which is called switching。
A lot of people will wonder about a few questions that are common in life, and let's get this straight。
Question one: why is there no signal in the deep, remote mountains since it's a remote fibre
The reason is simple. The base station was not unpaved. The fibre-optic is the main route and the base station is equivalent to the express delivery point at the door. There is no base station in the mountain, no radio waves from your mobile phone, no reception at the nearest “twirl station”, even if the network of thousands of miles of fibre-optics is developed, and this last part of the air link is broken and there is no signal。
Question two: why is the elevator, the cell phone in the basement bad
Radio waves have weak capacity to penetrate metal and thick concrete. Elevators have metal casings and thick walls in the basement that block electromagnetic waves. Cellular signals could not be successfully delivered to the outside base station, nor could the base station's signals come in, which could easily be intermittent. Many sub-district basements are equipped with signal amplifiers to solve this problem。
Question three: will there be a two-person signal jamming each other
Operators allocate different frequencies to different base stations and different mobile phones. It is equivalent to many parallel lanes, each of which allocates an exclusive channel. A large number of people in the same area make simultaneous calls, and when the tunnel is occupied, there will be calls to cardon, which will not be reached, such as large concerts, spring train stations, as is the case with network congestion。
Question four: is there a big difference between 5g calls and 4g and 2g calls
The bottom logic remains the same as the cell phone base station, the fibre-optic core network, the remote base station and the other cell phone. The difference is coding, radio frequency bands, transmission speed. The 5g bandwidth is larger, with lower delays, not just voice, but also high-resolution video, which is the principle。
There is also a critical knowledge point: radio waves and the voices we hear are completely different. Radio is invisible and deaf; it is a carrier carrying digital information of sound. Radio, wifi, basically, transmits information by radio waves, and the principles are consistent, but with different frequencies。
There's a lot of mistakes: the stronger the cell phone, the greater the radiation. On the contrary, when the signal is weak, mobile phones are much more radioactive when they are trying to magnify their power to launch radios; they are full of signals and they need only a small amount of power to communicate with the base station. The radiation from regular mobile phones is within national security standards and does not require excessive fear。
Let's compare the old ones to better understand the difference. The aircraft is wired all the way to the telephone line and is drawn directly from home to the room and is wired from beginning to end. Cell phones are a wireless, wired segment, and mobile phones travel to the base station for air radios; the base station crosses the river north and south, relying entirely on fibre-optic cable transmission。
A simple conclusion: cell phones do not have wires, except for the small part of the recent tower. Thousands of miles of long-distance transmission of information rely on deep-seated fibre-optic networks, an invisible communications network that sustains our daily mobile phone calls, micro-intelligence, short video access。
Technology looks amazing, but the bottom logic is not complicated. On each occasion, there were hundreds of thousands of base stations all over the country, with hundreds of thousands of kilometres of fibre-optic cables, working together。
Topical discussion
Did you ever think your cell phone was air-borne? Have you ever seen a cell phone without a signal in a basement or a mountain? Do you think there's a difference between a 5g call and an old phone call? You are welcome to talk in the comment section。
