| 367 / | HD | COMMUNICATIONS, ELECTRICAL: ACOUSTIC WAVE SYSTEMS AND DEVICES |
| 14 | DF | SEISMIC PROSPECTING {4} |
| 37 | DF | .~ Land-reflection type {6} |
| 38 | DF | .~.~ Signal analysis and/or correction {15} |
| 65 | ![]() | .~.~.~ Gain control {2} |
| 66 | DF | .~.~.~.~> Analog/digital compatible systems |
| 67 | DF | .~.~.~.~> Digital |