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What is group delay in signal processing?
In signal processing, group delay is the time delay of the amplitude envelopes of the various sinusoidal components of a signal through a device under test, and is a function of frequency for each component. Phase delay, in contrast, is the time delay of the phase as opposed to the time delay of the amplitude envelope.
What is group delay in optical communication?
The group delay (Tg) of an optical element (e.g. a dielectric mirror or a piece of optical fiber) is essentially the time delay experienced by a short (but not too short and not too intense) light pulse for propagation through that element. That time delay generally depends on the optical wavelength.
What does group delay mean in a filter?
So, group delay means a propagation delay through a filter, measured on the envelope of the signal. Let’s summarize again. Linear-phase filters delay the envelope of every signal by the same amount of time, called group delay, no matter what is the carrier frequency of the signal.
What does a delay of 0.4µs mean?
Its period is 1/250,000Hz = 4µs. Therefore, a delay of 0.4µs means a phase shift of 1/10 of a period, or 360 degrees /10 = 36 degrees. However, if the signal frequency is multiplied by 2 (500kHz), its period is 2µs, and the same 0.4µs delay now means a phase shift of 1/5 of a period or 72 degrees.
How is a nonlinear phase filter different from a simple delay?
FIGURE 2 – With a linear phase filter, all frequencies are delayed by the same amount of time. On the contrary, a nonlinear phase filter will have a non-constant group delay, meaning that frequency components will no longer be time-aligned. The delay I am talking about here is, in fact, a little different from a simple delay.
Why is the group delay higher for F2?
Therefore, the group delay is increased for signals in that frequency range. The group delay for frequency f2, which is inside this range, is higher than for f1, which is outside. What does that mean?