pitch-catch arrangement

Слово встречается в следующем контексте:
A transfer value shall be determined and used for all shear wave examinations to compensate for differences in surface,contour, finish, coatings and acoustical attenuation characteristics. This exercise will be performed for each and every nominal angle of refraction and frequency used for the test using two single crystal search units in a pitch and catch arrangement on both the applicable reference block and the work place.

Заранее спасибо