How does my tiny phone communicate with a cell tower so far away? How does it transmit my data to the cell tower?
In: 122
Over the last 100 years, humans have become very good at shaping radio waves to squeeze more data and range out of weaker signals.
How we transmit data on a radio wave affects how much data we can encode in it, and how easy it is to “hear it” against the background noise.
Early radio was Amplitude Modulated “AM”. AM signals are encoded in the power of the radio wave. It was very easy to create AM signals with primitive transmitters. And the receiver was very, very simple, consisting of essentially three core electronic components.
AM is very susceptible to noise, and you can hear it on AM radio today. We go around that by making AM transmitters very powerful, so the signal is much higher than the noise further away. High the power, the higher the Signal to Noise Ratio “SNR” will be at a given distance.
We eventually moved to Frequency Modulated “FM” radio receivers and transmitters. FM works by changing the frequency of the radio to encode the signal.
The circuits are still relatively simple but require transistors or vacuum tubes in the transmitter and receiver.
FM information isn’t tied to the transmitter’s power output and is less sensitive to interference from other electronics and the environment.
Another thing we do now, is encode the data as digital information instead of analog; using digital encoding, we can do error checking and improve SNR even more.
Today, more complex modulation techniques with digital data on modern communication radios improve signal-to-noise even more. These modulation techniques use properties like the phase of the wave and the shape of the wave to encode more data.
More advanced electronics let us send and receive vast amounts of data with very low power.
Cell towers must still be big and powerful and placed everywhere, sometimes only a mile apart. Towers still need to have big antennae and amplifiers to hear the small signal being sent by our low-power devices.
The advancements in how we squeeze data into radio waves let us increase the Signal to Noise ratio and get more data using less power.
The miniaturization of electronics has allowed us to use very advanced algorithms to manipulate radio waves in ways that would look like magic 100 years ago.
Latest Answers