| 702 / | HD | DATA PROCESSING: MEASURING, CALIBRATING, OR TESTING |
| 1 | DF | MEASUREMENT SYSTEM IN A SPECIFIC ENVIRONMENT {6} |
| 57 | DF | .~ Electrical signal parameter measurement system {6} |
| 66 | DF | .~.~ Waveform analysis {5} |
| 75 | ![]() | .~.~.~ Frequency {2} |
| 76 | DF | .~.~.~.~> Frequency spectrum {1} |
| 78 | DF | .~.~.~.~> By count (e.g., pulse) |