A fundamental feature of wireless (duplex) bidirectional communication systems is the way to separate the transmitted and received signals. We almost always find that the standard either establishes alternating them in time intervals, with the device quickly switching between transmission and reception, or transmitting them in different frequency bands and separating them by means of radiofrequency filters.
Just by looking at the bottom or rear part of an electronic IT device (such as a computer, router, monitor, etc.) or its accessories (mouse, keyboard or power source), we can identify a common feature: all of them have an identifying plate full of symbols. Each represents the product’s conformity with a series of rules or regulations applicable in a given country or economic area.
Following on from a previous article on DSL and its scientific bases, I now want to review the fundamentals of another technology: radio. As with a DSL, the ability to transmit data in any radio communications system – from the very first Marconi experiments to 5G networks – is bound by Shannon’s equation, based on the channel’s bandwidth and signal-to-noise ratio. In radio, we also have another interesting equation that can tell us the received signal strength when the transmitter power and frequency, antenna characteristics and distance to the receiver are known.
The growing number of electronic devices and wireless technologies providing ever-increasing performances and speeds requires a set of common standards to ensure EMC electromagnetic compatibility.
Ever since Michael Faraday’s discovery in 1831 of the phenomenon of magnetic induction, which James Maxwell later integrated in his well-known set of equations, we know that any change in an electric current produces a magnetic effect in its vicinity.