PHYS1008 Lecture Notes - Lecture 6: Pulse Repetition Frequency, Electric Charge, Record Producer
Document Summary
Transmission wave going through the new medium. Pulse-echo technique short pulses of ultrasound generated and detected, measured before the next pulse is applied. Transducer has insulator allows the vibrations to be detected. Pulsed sound waves used for imaging purposes. Allows depth of reflecting surfaces to be determined. Consists of grey where degree of whiteness depends on the echo strength. Placement of reflecting surface depends on time taken for echo to return. Depth (d) = (m/s) x (time for echo to return / 2) seconds. Pulse repetition frequency (prf, hz) number of times the crystal is pulsed per second. 2 = accounts for the total distance travelled to the reflector and back to the transducer (twice the depth of sampling) Spatial pulse length (spl, m) length of each pulse. Measured between points where the intensity is -20db relative to maximum intensity. Axial resolution (depth resolution) difference in depth between two points that can just be differentiated.
