RF signal characteristics in time domain

NP – Number of peaks  

CN – Number of cycles: CN = CP/2

Vpp – Peak-to-peak amplitude: Maximum deviation between peaks expressed in volts or % 

ΔT-20dB -  Pulse duration or waveform length

dA – Damping: relation between maximum amplitude and the adjacent peak.

Axial resolution

Ability of an ultrasonic signal to distinguish two separated reflectors along the direction of the sound propagation (Δz).

RF signal characteristics in frequency domain

fL – lower frequency

fU – upper frequency

fC – centre frequency: (fU-fL)/2

BW6dB[%] – Bandwidth: 100 *(fU-fL)/fC

Transducer classification by its bandwidth

The transducer transforms electrical energy into mechanical vibrations and vice versa. Due to mechanical damping of the transducer element a damped oscillation is also produced -in the material.

High damping pulse –

Wide band transducer

1 - 3 cycles

Medium damping pulse –

Medium band transducer

3 - 5 cycles

Low damping pulse –

Narrow band transducer

5 - 7 cycles

Axial resolution improves when pulse duration decreases

Reference Axial

Resolution (Δz)

Axial resolution decreases when pulse duration increases