Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2002-01-23
2004-02-24
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S568400, C340S687000
Reexamination Certificate
active
06696949
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to electrical communications systems and, more particularly, to auxiliary equipment for preventing televisions or VCRs from being utilized as eavesdropping devices.
BACKGROUND OF THE INVENTION
Diplomats have used information available from CNN and other television news networks for years in conducting their business. Unfortunately, their access to this information has been limited because televisions, VCRs, and other electronic devices can be used for eavesdropping purposes. It is well known that conductors employed by a television to convey electrical power and television signals can be used by sophisticated bugging devices to transmit intercepted conversations to remote locations. One solution to this problem has been to laboriously connect and disconnect the power and signal conductors from a television after each use. This procedure has been found to wear out electrical connectors and inconvenience diplomats. In some cases, inattention has led to conductors not being disconnected for extended periods of time. Enforcing rules requiring disconnection of power and signal conductors from a television in an area intended to be secure is difficult.
SUMMARY OF THE INVENTION
In light of the problems associated with known manner in which televisions are disconnected from power and television signal sources so as to render them secure against eavesdropping, it is a principal object of the invention to provide a television security device that permits the quick, easy, and simultaneous disconnection of a television from power and RF or data signal sources with the manipulation of a single switch. Once disconnected, this device terminates television coaxial lines with their nominal characteristic impedance and isolates fortuitous ground paths to reduce conducted and radiated signal emissions. Moreover, the security device incorporates a current sensor and an alarm to notify a user that disconnection of the sort described has not been made.
It is another object of the present invention to provide a security device of the type described that can be used to make apparatus other than televisions secure from eavesdropping. For example, the security device could be used with VCRs and personal computers connected to remote networks. In fact, the security device can be employed with virtually any electronic apparatus connected by wire to remote electrical and signal sources.
It is a further object of the invention to provide a security device that internally forms multiple electrical signal paths or loops while in a secure mode to reduce the likelihood of a breach by sophisticated eavesdropping equipment.
It is an object of the invention to provide improved elements and arrangements thereof in a television security device for the purposes described which is lightweight in construction, inexpensive to manufacture, and dependable in use.
Briefly, the security device in accordance with this invention achieves the intended objects by featuring a rectifier and a pair of conductors connecting the rectifier with a source of alternating current. A switch, associated with the first conductors, selectively breaks the connection between the rectifier and alternating current power source. An electrical outlet or bank of such outlets is connected by a pair of second conductors to the first conductors such that the switch also breaks the connection between the outlet and alternating current power source. A power cutoff relay is connected to the voltage regulator output so as to be energized by direct current from it. A contact set is closed by the power cutoff relay to connect the alternating current source with the electrical outlet through the second conductors. An optocoupler current sensor senses the flow of alternating current through the electrical outlet and operates a transistor switch to control the flow of direct current to an alarm when alternating current flow is sensed. A pair of jacks is connected together by a pair of third conductors through which a communications signal is passed. A pair of signal transfer relays is connected to the voltage regulator output. The signal transfer relays are connected to wideband unbalanced to balanced radio frequency (RF) signal transformers connected to ground isolated signal jacks and resistive terminations. When energized, the relays connect the signal jacks together. Otherwise, the signal lines are terminated and isolated from ground. In this state, all RF energy is dissipated in the resistive loads and there is no reflected power on the signal lines.
The foregoing and other objects, features and advantages of the present invention will become readily apparent upon further review of the following detailed description of the preferred embodiment as illustrated in the accompanying drawings.
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Greiner Stephen R.
Hofsass Jeffery
Stone Jennifer
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