Radio Frequency Wave Characteristics

Modulation is the way that a signal is modified to represent bits, allowing it to be sent across the radio to the receiver using the hardware and software available. This is done by utilising three basic elements that effect the waveform: frequency, amplitude, and phase.

Frequency is based on the timing between the signals and is usually measured by the number of wave cycles in each time frame (for example one second). An example is 1Hz represents 1 wave being sent with that cycle, while 1KHz (1,000 Hz) shows that 1,000 cycles have happened in that given space. This is the same even for the 2.4Ghz and 5Ghz frequencies, as you can see the 5Ghz will pass nearly double the amount of waves pre cycle then 2.4Ghz, but as you may recall from my post about home Wi-Fi, 5Ghz travels less distance due to its higher frequency.

  

You tend to find frequency is not used within a wireless environment as switching between different frequencies means you could start interfering with other devices already using those frequencies. Think of it as switching lanes on a motor way, it is only a matter of time until you move to a lane and bump into another car.

Amplitude: this increases the waveforms volume, aka the height of the wave. The higher the amplitude, the higher the peak; the lower the amplitude the lower the peak. In turn this can be used to represent a different value depending on height. A waveform with a high amplitude is represented as having a value of 1 and a lower amplitude represented as 0.

 

Phase: this is focused on the time of the signal between the peaks of the waveform. Unlike frequency and amplitude this not done by looking at a single wave but by comparison of two waves and their time to peak within their own cycles. For example, if the second wave reached its peak at the same time as the previous wave they are in perfect phase and 0 degrees out. If, however the second peak is slightly before or after the original then it is deemed out of phase and it will have a phase shift value in degrees.

 
The different phase degrees can have values assigned to them and due to the wide array of combinations that you can have in comparing signals it is heavily utilised in wireless modulation.

 

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