Phase-shift keying
Phase-shift keying (PSK) is a way of sending information wirelessly. Think of it like a secret code between two people. Let’s say two friends need to communicate using flashlights from a distance. But, they cannot shout or use a walkie-talkie. So, they agree on a secret code. They decide to use the flashlight’s on/off button. When the flashlight is on, that means “yes” and when the flashlight is off, that means “no”. The problem is, if they just use on/off only, they cannot convey much information.
In PSK, instead of using on/off, we use something called “phase”. Phase is a bit like a pie. Imagine a whole pie is 360 degrees. The spinner wheel in the game Twister has the pie divided into four equal parts of 90 degrees. So, each slice of the pie is 90 degrees. This could represent a different message. For example, slice one is “yes”, slice two is “no”, slice three is “maybe”, and slice four is “I'm not sure”.
Next, we add a special device that can change the phase of the message. This device could be like the filter on a flashlight. It can change the focus of the light, which can change the code. So, if we spin the filter to different angles, we can change which slice of the pie is lit up/active. This makes PSK very useful as we can send lots more messages.
Now, let's come back to wireless communication. Instead of flashlight, we use radio waves. Instead of the phase filter, we use very small electrical circuits that can change the phase of the wave. The circuits can change the wave many times per second (for example, 250 times per second). This means we can send messages very quickly. We can have the phase change from 0 to 90 degrees for a “yes” and 180 to 270 degrees for a “no”. This particular type of PSK is called “Quadrature PSK” or QPSK.
So, when we want to send a message over a long distance, we first turn it into a series of 1s and 0s (binary code). Then, we use PSK to change the phase (angle) of the radio wave between 0, 90, 180, and 270 degrees to send each bit of the code. The receiver (the person receiving the message) knows what each phase change means for the 1s and 0s, so they can read the message.
In summary, Phase-shift keying is like having different slices of pie represent different messages. We can change the slice or “phase” of the pie by spinning a filter. For communication over a distance, we use radio waves and circuits to achieve this phase shift, allowing us to send lots of messages very quickly.
In PSK, instead of using on/off, we use something called “phase”. Phase is a bit like a pie. Imagine a whole pie is 360 degrees. The spinner wheel in the game Twister has the pie divided into four equal parts of 90 degrees. So, each slice of the pie is 90 degrees. This could represent a different message. For example, slice one is “yes”, slice two is “no”, slice three is “maybe”, and slice four is “I'm not sure”.
Next, we add a special device that can change the phase of the message. This device could be like the filter on a flashlight. It can change the focus of the light, which can change the code. So, if we spin the filter to different angles, we can change which slice of the pie is lit up/active. This makes PSK very useful as we can send lots more messages.
Now, let's come back to wireless communication. Instead of flashlight, we use radio waves. Instead of the phase filter, we use very small electrical circuits that can change the phase of the wave. The circuits can change the wave many times per second (for example, 250 times per second). This means we can send messages very quickly. We can have the phase change from 0 to 90 degrees for a “yes” and 180 to 270 degrees for a “no”. This particular type of PSK is called “Quadrature PSK” or QPSK.
So, when we want to send a message over a long distance, we first turn it into a series of 1s and 0s (binary code). Then, we use PSK to change the phase (angle) of the radio wave between 0, 90, 180, and 270 degrees to send each bit of the code. The receiver (the person receiving the message) knows what each phase change means for the 1s and 0s, so they can read the message.
In summary, Phase-shift keying is like having different slices of pie represent different messages. We can change the slice or “phase” of the pie by spinning a filter. For communication over a distance, we use radio waves and circuits to achieve this phase shift, allowing us to send lots of messages very quickly.
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