What are the 4 characteristics of deeper imaging?

• A. Less listening; Shorter PRP; Higher PRF; Higher duty factor
• B. More listening; Longer PRP; Lower PRF; Lower duty factor
• C. More listening; Shorter PRP; Higher PRF; Higher duty factor
• D. Less listening; Longer PRP; Higher PRF; Lower duty factor

Answer: (B)

Deeper imaging relies on having more time to listen for echoes from greater depths. To accommodate the longer travel time of the waves, the system increases the listening window between pulses, which shows up as a longer pulse repetition period. Since the pulse repetition frequency is the inverse of the PRP, a longer PRP means a lower PRF. With a longer cycle time, the fraction of time the transmitter is actually on (the duty factor) becomes lower, assuming the transmit pulse duration stays similar. So deeper imaging is characterized by more listening, longer PRP, lower PRF, and lower duty factor. This combination also means a slower frame rate, which is the trade-off for imaging deeper structures.