A transducer with a 3 MHz center frequency produces a pulse range of 1 MHz to 5 MHz; the bandwidth is 4 MHz. Which set correctly states these values?

• A. 0.5 to 2.5 MHz; 2.0 MHz
• B. 1 MHz to 5 MHz; 4 MHz
• C. 2-6 MHz; 4 MHz
• D. 1.5 to 3.5 MHz; 2.0 MHz

Answer: (B)

Relate center frequency, bandwidth, and the pulse’s frequency span. The pulse range is the lowest to highest frequency present in the transmitted spectrum. The bandwidth is the difference between those high and low frequencies. The center frequency is the midpoint of that range, averaging the high and low ends.

With a center frequency of 3 MHz and a bandwidth of 4 MHz, the ends are 3 ± 2 MHz, giving a low end at 1 MHz and a high end at 5 MHz. So the pulse range is 1 to 5 MHz and the bandwidth is 4 MHz. This checks out because the center frequency is the midpoint of the range: (1 + 5) / 2 = 3 MHz, and the width is 5 − 1 = 4 MHz.