Avionics
Intermediate

Radar Maximum Unambiguous Range

Farthest range at which a pulse echo returns before the next pulse is sent; beyond it, targets appear at false (aliased) ranges.

Formula

Rmax=c2PRFR_{max} = \dfrac{c}{2\,PRF}

Variables

R_maxMax unambiguous range
cSpeed of light
PRFPulse repetition frequency

Example

PRF 1000 Hz: R = 3×10⁸ ÷ (2×1000) = 150 km

Did You Know?

There is a fundamental trade-off: raising the PRF measures fast targets better but shrinks the unambiguous range — the “range–Doppler dilemma” of pulsed radar.

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