The frequency response of a digital filter H($\omega$) has the following characteristics
Passband: 0.95$\le$|H($\omega$|$\le$1.05 for 0$\le$$\omega$$\le$0.3$\pi$ and
Stopband: 0$\le$|H($\omega$)|$\le$0.005 for 0.4$\pi$$\le$$\omega$$\le$$\pi$,
where $\omega$ is the normalized angular frequency in rad/sample.. If the analog upper cut off frequency for the passband of the above digital filter is to be 1.2 kHz, then the sampling frequency should be $\_\_\_\_\_$ kHz.