To solve this problem, we need to find the auto-correlation function of a rectangular pulse and analyze its characteristics.
- Auto-correlation function: The auto-correlation function of a signal \( x(t) \), denoted as \( R_x(\tau) \), is defined as the convolution of the signal with its time-reversed version. Mathematically:
\[ R_x(\tau) = \int_{-\infty}^{\infty} x(t) x(t - \tau) dt \]
- Rectangular Pulse: A rectangular pulse of duration \( T \) is a signal that is 1 for \( t \) in the interval \( [0, T] \) and 0 otherwise. Its auto-correlation function can be calculated by overlapping the pulse with a shifted version of itself and measuring the overlap as a function of the shift.
The auto-correlation function of a rectangular pulse of duration \( T \) is known to produce a triangular pulse. This is because the overlap between the original pulse and the shifted version decreases linearly as the shift increases. Therefore, the auto-correlation function is a triangular pulse with a base duration of \( 2T \).
The auto-correlation function of a rectangular pulse of duration \( T \) is A triangular pulse of duration \( 2T \).
What is the voltage across the inductor at $t=0$? (Circuit diagram provided: A 60V voltage source in series with a switch that closes at $t=0$, a 30 ohm resistor, and a 15H inductor.) 
The overall impulse response of the system shown in figure is given by (Block diagram provided: Input $X(n)$ splits. One path goes to $h_1[n]$, another to $h_2[n]$. The outputs of $h_1[n]$ and $h_2[n]$ are subtracted. This result is convolved with $h_3[n]$. Separately, $X(n)$ also goes to $h_5[n]$. The output of $h_3[n]$ and $h_5[n]$ are subtracted. This result is convolved with $h_4[n]$ to produce $y(n)$.) 