| 摘要 |
PCT No. PCT/EP90/01914 Sec. 371 Date May 1, 1992 Sec. 102(e) Date May 1, 1992 PCT Filed Oct. 26, 1990 PCT Pub. No. WO91/07798 PCT Pub. Date May 30, 1991.In order to protect computers and the like against the pick up, the recording and the unauthorized use of data from the computers during the working thereof, and to protect them against high energy transient disturbances taking place on the main A.C. power line, a filter unit (1) is foreseen comprising a plurality of sections (19) comprising inductances (21) and capacitances (23), between which it is interposed at least a gas-discharge surge arrester (25) and varistors (27), and masking unit (3) comprising a power supply (31), a white noise generator (33) and an amplifier (35) emitting from the antenna circuit (61) said properly amplified white noise which is completely random and unpredictable, and therefore impossible to be decoded.
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