An oceanographic research station transmits telemetry and acoustic signals back to a monitoring vessel.
Explain the difference between an analogue signal and a digital signal used in this telemetry.
Explain one reason why digital signals are preferred over analogue signals for long-distance underwater telemetry where signal degradation is significant.
The vessel also uses active acoustic transducers to map the seabed. To ensure that acoustic waves at different frequencies spread out with a wide, uniform angular distribution into the water, the system utilizes a small transducer head for high-frequency sonar pulses and a much larger transducer head for low-frequency sonar pulses.
Explain, using principles of wave diffraction, why these different transducer sizes are necessary to achieve similar angular spreading for different frequencies.