Interpret periods from fourier transfrom graph of periodic impulse signals
Assuming you are in the continuous-time domain, given the periodic impulse train with a period of $T_0$ 

$$ x(t) = \sum_k \delta(t - k T_0)$$

then its CTFT will be another periodic impulse train in the frequency domain 
$$ X(\omega) = \frac{2\pi}{T_0} \sum_k \delta( \omega - k\omega_0)$$

Where the period $\omega_0$ of the frequency impulses is related to the period of the time impulses as

$$ \omega_0= \frac{2\pi}{T_0} $$

hence the time period will be given as:

$$ T_0 = \frac{2\pi}{\omega_0} $$

In your case, if $T_0 = 30$  then $\omega_0$ will be 
$$ \omega_0 = \frac{2\pi}{30} = \frac{\pi}{15} $$

Conversely, given the frequency period as $\frac{2\pi}{30}$ then the corresponding time period will be $T_0 =  30$.

Note that there will be errors in your computation depending on how you simulate the impulse train or CTFT.