| (11) | EP 2 284 575 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Method for generating spread spectrum driver signals for a seismic vibrator array using multiple biphase modulation operations in each driver signal chip |
(57) A method for generating seismic energy for subsurface surveying include operating a first seismic vibrator above an area of the subsurface to be surveyed and operating at least a second seismic vibrator above the area substantially contemporaneously with the operating the first seismic vibrator. The first and the second vibrators each have a different selected frequency response. The first and second vibrators each is operated by a same direct sequence spread spectrum signal, wherein a different number of modulation operations for each logical value in the direct sequence spread spectrum signal is selected for each vibrator.
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