If PRF is increased, what happens to the range unambiguous limit R_amb?

If PRF is increased, what happens to the range unambiguous limit R_amb?

• A. It decreases
• B. It increases
• C. It stays the same
• D. It becomes infinite

Answer: (A)

The range unambiguous limit is the maximum distance at which a return can be linked to the specific transmitted pulse without confusion from echoes of other pulses. It depends on how long you wait between pulses. Since the time between pulses is T = 1/PRF, the echoes must be received within that interval, which corresponds to a distance of R_amb = c/(2 PRF). Therefore, increasing PRF shortens that time window and reduces the unambiguous range. In other words, higher PRF makes the unambiguous range smaller because echoes from farther targets can overlap with the next pulse. For example, doubling PRF roughly halves R_amb, illustrating the inverse relationship.

The range unambiguous limit is the maximum distance at which a return can be linked to the specific transmitted pulse without confusion from echoes of other pulses. It depends on how long you wait between pulses. Since the time between pulses is T = 1/PRF, the echoes must be received within that interval, which corresponds to a distance of R_amb = c/(2 PRF). Therefore, increasing PRF shortens that time window and reduces the unambiguous range. In other words, higher PRF makes the unambiguous range smaller because echoes from farther targets can overlap with the next pulse. For example, doubling PRF roughly halves R_amb, illustrating the inverse relationship.