GB2186466B - Security device for a video output unit - Google Patents

Security device for a video output unit

Info

Publication number
GB2186466B
GB2186466B GB8608103A GB8608103A GB2186466B GB 2186466 B GB2186466 B GB 2186466B GB 8608103 A GB8608103 A GB 8608103A GB 8608103 A GB8608103 A GB 8608103A GB 2186466 B GB2186466 B GB 2186466B
Authority
GB
United Kingdom
Prior art keywords
vdu
frequencies
radiation
output unit
security device
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB8608103A
Other versions
GB2186466A (en
Inventor
Richard C Marshall
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DATA HOLKEN AB
EMC Datacare Ltd
Original Assignee
DATA HOLKEN AB
EMC Datacare Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB868600210A external-priority patent/GB8600210D0/en
Application filed by DATA HOLKEN AB, EMC Datacare Ltd filed Critical DATA HOLKEN AB
Publication of GB2186466A publication Critical patent/GB2186466A/en
Application granted granted Critical
Publication of GB2186466B publication Critical patent/GB2186466B/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/40—Jamming having variable characteristics
    • H04K3/42—Jamming having variable characteristics characterized by the control of the jamming frequency or wavelength
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/40—Jamming having variable characteristics
    • H04K3/46—Jamming having variable characteristics characterized in that the jamming signal is produced by retransmitting a received signal, after delay or processing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/80—Jamming or countermeasure characterized by its function
    • H04K3/82—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection
    • H04K3/825—Jamming or countermeasure characterized by its function related to preventing surveillance, interception or detection by jamming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K2203/00—Jamming of communication; Countermeasures
    • H04K2203/10—Jamming or countermeasure used for a particular application
    • H04K2203/14—Jamming or countermeasure used for a particular application for the transfer of light or images, e.g. for video-surveillance, for television or from a computer screen
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K2203/00—Jamming of communication; Countermeasures
    • H04K2203/30—Jamming or countermeasure characterized by the infrastructure components
    • H04K2203/32—Jamming or countermeasure characterized by the infrastructure components including a particular configuration of antennas
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K2203/00—Jamming of communication; Countermeasures
    • H04K2203/30—Jamming or countermeasure characterized by the infrastructure components
    • H04K2203/34—Jamming or countermeasure characterized by the infrastructure components involving multiple cooperating jammers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
    • H04K3/00—Jamming of communication; Counter-measures
    • H04K3/40—Jamming having variable characteristics
    • H04K3/44—Jamming having variable characteristics characterized by the control of the jamming waveform or modulation type

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Burglar Alarm Systems (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

This comprises a jamming apparatus including an r.f. transmitter to jam intelligence carrying stray r.f. radiation from visual display units (VDU's). The apparatus generates swamping radiation which prevents decoding of a video signal from the VDU, in a relevant frequency band. The radio transmitter has one or more antennae 3a, 3b that are supplied with energy at a plurality of frequencies by the action of digital division and pseudo-random sequence generator circuits 4. The oscillator 1 from which these frequencies are derived may be phase-locked to the line-scan frequency of the VDU to be protected by means that include a coupling loop 10 that is immersed in the magnetic field of the said VDU. Correct operation is signalled to the user by indicator 13 and its associated circuit 14. <IMAGE>
GB8608103A 1985-04-19 1986-04-03 Security device for a video output unit Expired GB2186466B (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
GB8510129 1985-04-19
GB8525678 1985-10-18
GB868600210A GB8600210D0 (en) 1985-10-18 1986-01-07 Security device for video output unit

Publications (2)

Publication Number Publication Date
GB2186466A GB2186466A (en) 1987-08-12
GB2186466B true GB2186466B (en) 1989-07-12

Family

ID=27262656

Family Applications (1)

Application Number Title Priority Date Filing Date
GB8608103A Expired GB2186466B (en) 1985-04-19 1986-04-03 Security device for a video output unit

Country Status (1)

Country Link
GB (1) GB2186466B (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE500276C2 (en) * 1991-06-24 1994-05-24 Shield Research In Sweden Ab Method and apparatus for preventing external detection of signal information
IT1259383B (en) * 1992-04-02 1996-03-12 PROTECTION DEVICE FOR COMPUTERS AND SIMILAR
IL119694A0 (en) * 1996-11-26 1997-06-10 Point Ltd V A method and device to disable cellular communication
GB2388275B (en) * 2002-04-30 2005-11-02 Hewlett Packard Co Wireless data network security

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217550A (en) * 1962-09-28 1980-08-12 Blassel Pierre P Radio jamming device
US4342119A (en) * 1980-08-27 1982-07-27 The United States Of America As Represented By The Secretary Of The Air Force Multi-tone jammer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4217550A (en) * 1962-09-28 1980-08-12 Blassel Pierre P Radio jamming device
US4342119A (en) * 1980-08-27 1982-07-27 The United States Of America As Represented By The Secretary Of The Air Force Multi-tone jammer

Also Published As

Publication number Publication date
GB2186466A (en) 1987-08-12

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Legal Events

Date Code Title Description
732 Registration of transactions, instruments or events in the register (sect. 32/1977)
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20050403