Mock Test 1 — Communication Systems

The block in a communication system that converts non-electrical to electrical signals:

The size of antenna for $1$ kHz audio direct transmission is impractical because:

For ground wave propagation, maximum useful range is about:

The frequency range of microwaves:

An AM wave has $V_{\max} = 24$ V, $V_{\min} = 8$ V. Modulation index:

The bandwidth required for transmission of $20$ kHz audio by AM:

Side bands in AM with $f_c = 5$ MHz and $f_m = 5$ kHz:

Distance of line-of-sight from a $100$ m tall TV antenna:

FM is preferred over AM for:

Sky wave propagation uses:

Carrier frequency $1$ MHz amplitude modulated by $5$ kHz audio. Bandwidth (in kHz):

Modulation index of an AM wave with $V_{\max} = 30$, $V_{\min} = 10$, multiplied by $10$ (integer):

Two antennas: transmitter $h_T = 50$ m, receiver $h_R = 32$ m. Maximum line-of-sight distance (km, rounded, $R = 6400$ km, use $\sqrt{640000} = 800$):

Assertion (A): Sky wave propagation is not possible for very high frequencies (> 30 MHz). Reason (R): Above 30 MHz, the EM waves penetrate the ionosphere instead of being reflected.

Assertion (A): Frequency modulation is preferred for high-quality audio broadcasting. Reason (R): FM has better noise immunity since noise mostly affects amplitude, not frequency.