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Sign inPAUT acquisition rate
A phased array instrument fires one law per pulse. The rate at which complete frames arrive is therefore PRF / (laws × averaging). Every law added to the sweep, every extra focal depth and every additional averaging pass divides the frame rate by the same factor.
The PRF itself is capped by the sound path. The next pulse must not be fired before the echoes from the last one have died away, otherwise wrap-around signals from the previous shot appear in the display at false ranges. The absolute ceiling is c / (2 × range); in practice instruments are run well below it to let multiple back wall reflections decay.
Frame rate is the number that limits productivity. Combined with the required scan axis resolution it fixes the maximum scan speed, and exceeding that speed means skipped acquisition points - missing lines in the C-scan that an encoder will happily interpolate over unless data completeness checks are switched on.
PRF_max = c / (2 × range) PRF_eff = min(PRF_set, PRF_max) frame rate = PRF_eff / (laws × averaging)
- The PRF ceiling here is the bare wrap-around limit. Run at a fraction of it so that multiple back wall echoes have decayed.
- Instruments also cap PRF by duty cycle and by pulser heating - the value set may not be the value achieved.
Reference: General engineering - PRF, law count and wrap-around limit.
