Phase

What is it?

As a sinoidal signal in the time domain can be defined as

s(time)=amplitude * sin(2Pi*frequency * time + phase)

the phase describes an 'offset' of the signal along the time axis and defines the 'zero crossing' of the signal. An sinoid signal is periodic, therefore usually only phase values from +/-180deg are used.

An Example

You see here an sinoidal signal with a frequency of 1kHz and an amplitude of 2 Volts. Time scale is -1msec..+1msec. The signal is shown with 3 different phases, from left to right:

• -60 degree
• 0 degree
• +60 degree

Please have a look at the zero crossings!

Note: the phase can be either expressed as +/-Pi or +/-180deg. The signal itself can be described as cosine or sine, both is equivalent and up to you depending where you define time = 0.

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