| 摘要 |
In a method and apparatus for encoding signals, signals are passed through a body of a material that modifies a characteristic of signals passing therethrough, such as an acousto-electromagnetic. Energy is applied to the body for establishing a standing wave therein, so that the standing wave controls the passage of signals through said body. The energy may be applied by a piezoelectric element. The body or the piezoelectric element may be removable, to form an encoding key.
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