| 摘要 |
A pressure pulse generator comprising a circuit (12) filled with a pressure iluid, and at least one communication channel (15) that is connected to the circuit and via which the pressure fluid can flow into and out of the circuit. The pressure pulse generator comprises a first pair (8, 9) and a second pair (10, 11) of electrically controlled valves that are connected in series, and the first pair of valves (8,9) is arranged in said circuit (12) upstream the at least one communication channel (15), and the second pair of valves (10, 11) is arranged in said circuit (12) downstream the at least one communication channel (15).
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