lewando said:
That is exactly right.smart_worker said:
You might want to indicate (for others who might want to follow your logic) what is so special about "4" that leads you to classify the signal as you have. What if the result was "5"?
A power signal is a type of signal that has a finite power value, meaning that the energy of the signal is spread over an infinite period of time. It is represented by the formula P = lim T->∞ (1/T ∫ |x(t)|² dt), where P is the power value and T is the length of the signal. A common example of a power signal is an alternating current (AC) signal.
An energy signal is a type of signal that has a finite energy value, meaning that the signal has a finite duration and the energy is concentrated within that duration. It is represented by the formula E = ∫ |x(t)|² dt, where E is the energy value and t is the time variable. A common example of an energy signal is a pulse signal.
The notation u[n] - u[n-4] represents a discrete signal that is equal to 0 for n < 0, 1 for 0 ≤ n < 4, and 0 for n ≥ 4. In other words, it is a unit step function that is delayed by 4 units.
To calculate the power value, we can use the formula P = lim N->∞ (1/N ∑ |x[n]|²), where N is the length of the signal. In this case, the length is 4, so the power value will be 1/4. To calculate the energy value, we can use the formula E = ∑ |x[n]|², where n ranges from -∞ to ∞. In this case, the energy value will be 4.
The signal u[n] - u[n-4] has a finite power and energy value, making it a power and energy signal. It is a commonly used signal in signal processing and is often used as a test signal in systems analysis. It is also used in the analysis of linear systems and control systems.