Patent US4039451A successfully refreshed from Google Patents.
EP0240328A2
Expired / Lapsed
EP
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Computer security device
Assignee: Datasafe Ltd
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Filing: 1987-04-01
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Granted: —
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Expires: 2007-04-01
Abstract
Abstract With a view to preventing access to data stored in a computer installation by remote sensing of stray electromagnetic radiation emitted by the installation, a transmitter is provided within a housing 8 for transmitting electromagnetic radiation over a frequency range which includes at least the main frequencies at which stray radiation is emitted by the installation. An antenna 9 is coupled to the transmitter and attached to the installation. In this manner the stray radiation emitted by the installation is substantially masked by the radiation transmitted by the device. Such a device is capable of protecting substantially any type of computer installation, and of preventing an unauthorised person from reading displayed data or other information within the computer by means of a remote receiver, visual display unit or data reader.
Inventors
- 👤 Sean Michael Walker
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 11:29
CPC Classifications
H; H04; H04K; H04K3/00; H04K3/80; H04K3/82; H04K3/825; G; G06; G06F; G06F21/00; G06F21/70; G06F21/82; G06F21/84; H04K2203/00; H04K2203/10; H04K2203/14; H04K3/40; H04K3/42; H04K3/45
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
91 words
A computer security device for preventing access to data stored in a computer installation by remote sensing of stray electromagnetic radiation emitted by the installation, characterised in that the device (7) comprises a transmitter for transmitting electromagnetic radiation over a frequency range which includes at least the main frequencies at which stray radiation is emitted by the installation, and antenna means (9) coupled to the transmitter and adapted for attachment to the installation, whereby the stray radiation emitted by the installation is substantially masked by the radiation transmitted by the device.
Claim 2
Dependent Claim
91 words
A computer security device for preventing access to data stored in a computer installation by remote sensing of stray electromagnetic radiation emitted by the installation, characterised in that the device (7) comprises a transmitter for transmitting electromagnetic radiation over a frequency range which includes at least the main frequencies at which stray radiation is emitted by the installation, and antenna means (9) coupled to the transmitter and adapted for attachment to the installation, whereby the stray radiation emitted by the installation is substantially masked by the radiation transmitted by the device.
Claim 3
Dependent Claim
35 words
A device according to claim 1, wherein the antenna means (9) is in the form of a flexible elongate member which may be positioned, in use, to lie close to parts of the computer installation.
Claim 4
Dependent Claim
13 words
A device according to claim 2, wherein the antenna means (9) is coiled.
Claim 5
Dependent Claim
31 words
A device according to claim 1, 2 or 3, wherein the transmitter includes a transmitting diode (13) and amplifying means (15, 16, 17) for amplifying the output of the diode (13).
Claim 6
Dependent Claim
15 words
A device according to claim 4, wherein the transmitting diode (13) is a zener diode.
Claim 7
Independent Claim
40 words
A device according to any preceding claim, further comprising a receiver (30;40) for receiving the stray radiation emitted by the installation, and processing means (32;45) for causing the transmitter (33;46) to transmit a radiation pattern determined by the received radiation.
Claim 8
Dependent Claim
61 words
A device according to claim 6, further comprising phase detection means (42) for detecting the phase of a video data switching signal within the installation, and phase comparison means (44) for comparing the phases of the video data switching signal and the received radiation and for controlling the phase of the transmitted radiation in dependence on the result of the comparison.
Claim 9
Dependent Claim
18 words
A device according to claim 7, wherein the phase detection means (42) comprises a capacitative and/or inductive probe.
Claim 10
Dependent Claim
54 words
A device according to claim 7, wherein the phase detection means (42) comprises a delay line adapted to be connected to a video data line of the installation and to supply to the phase comparison means (44) a signal delayed by a predetermined amount with respect to a signal in the video data line.
Claim 11
Dependent Claim
92 words
A computer installation incorporating a computer security device for preventing access to data stored in the installation by remote sensing of stray electromagnetic radiation emitted by the installation, characterized in that the device (7) comprises a transmitter for transmitting electromagnetic radiation over a frequency range which includes at least the main frequencies at which stray radiation is emitted by the installation, and antenna means (9) coupled to the transmitter and attached to the installation, whereby the stray radiation emitted by the installation is substantially masked by the radiation transmitted by the device.
Claim 12
Dependent Claim
92 words
A computer installation incorporating a computer security device for preventing access to data stored in the installation by remote sensing of stray electromagnetic radiation emitted by the installation, characterized in that the device (7) comprises a transmitter for transmitting electromagnetic radiation over a frequency range which includes at least the main frequencies at which stray radiation is emitted by the installation, and antenna means (9) coupled to the transmitter and attached to the installation, whereby the stray radiation emitted by the installation is substantially masked by the radiation transmitted by the device.
References Cited (Backward Citations)
No citation records indexed.
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