FSK

FSK refers to Frequency Shift Keying and it is a way to transmit digital signals. Before understanding what exactly FSK is and what it does, it is important to understand where it came from. Frequency Shift Keying has been around since the middle of the 1900s, where its initial speed was no more than forty five bits per second. As personal computers became more widely used and as networks were fist being introduced, the slow speed of FSK was extremely tedious, because transmitting large amounts of data, programs, and even simple text documents, could take hours to be completed. At this point, it was not even possible to transmit images.

It was not until the 1970s that faster modems were being created. Since then, the search for bandwidth has become as much of an obsession as the search for gold way back when. In binary, there are two states, logic 0 - or low - and logic 1 - high. They are represented by a respective analog waveform, one for each state. A wave at a particular frequency represents logic 0 and, conversely, a wave at an entirely different frequency represents logic 1. The transmission of binary information from a computer to a Frequency Shift Keying occurs in a modem, where the binary data is converted.

The transmission can take place over several different things, including phone lines, cables, fiber optic cables (or optical fiber), and various means of wireless media. Likewise, incoming Frequency Shift Keying signals can be converted through a modem, into digital low states and digital high states that the computer can comprehend. These days, typical modems are able to transmit more than one million bytes per second, while modems which use optical fibers can run at even higher speeds. The past and continued progress of Frequency Shift Keying technology continues to grow, even though the fundamentals of how FSK works has hardly changed since it was first introduced.

Al Munroe writes on topics such as FSK, QPSK and 8PSK for The Tech FAQ.