A random binary wave $y(t)$ is given by

$$y(t) = \sum_{n = -\infty}^{\infty}X_{n}\:p(t-nT-\phi)$$

where $p(t)=u(t)-u(t-T),u(t)$ is the unit step function and $\phi$ is an independent random variable with uniform distribution in $[0,T].$The sequence $\{X_{n}\}$ consist of independent and identically distributed binary valued random variables with $P\{X_{n} = +1\} = P\{X_{n} = -1\} = 0.5$ for each $n.$

The value of the autocorrelation $R_{yy}\left(\dfrac{3T}{4}\right) \underset{=}{\Delta} E\left[y(t)y\left(t-\dfrac{3T}{4}\right)\right]$ equals _________.