Interactive video distribution systems – Video distribution system with upstream communication – Transmission network
Reexamination Certificate
1998-09-15
2002-09-17
Faile, Andrew (Department: 2611)
Interactive video distribution systems
Video distribution system with upstream communication
Transmission network
C725S119000, C725S127000, C725S149000
Reexamination Certificate
active
06453473
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of data communication through cable television networks and, in particular, to an access device for enhancing security of data transmitted through cable television networks.
BACKGROUND OF THE INVENTION
In recent years, increased utilization of the Internet as a means of transmitting information has revealed inadequacies in existing twisted pair telephone systems for transmitting and receiving data. As sources of information have increased their availability of information, not just incrementally but multiple orders of magnitude, users of this information have demanded commensurate increases in the rate of delivery of the desired information.
In an attempt to meet this demand, existing twisted pair telephony systems have moved from a data transmission rate of 300 bps to rates in excess of 28.8 Kbps (the EIA-V.34 standard) over standard phone lines. Further incremental increases in data transmission rates can be achieved by utilizing specially conditioned lines and various modulation schemes. However, these increases also will involve significant increases in cost of service.
The cost/performance constraints of current telephone systems has led to the use of cable television lines for transmitting data. By utilizing community antenna television (CATV) modems, a nominal increase in the data transmission rate from 28.8 Kbps to 10 Mbps has been achieved; an increase of from 300 to 500 times. The bandwidth of the installed base varies from 300 MHz to 1.2 GHz, with a high bandwidth capacity and the ability to increase that bandwidth in the future. The information industry has recognized this potential and various enterprises have developed cable modems for this purpose. However, current cable television systems have inherent drawbacks relating to the transmission and reception of data.
One drawback in utilizing cable television systems for data traffic is the decrease in security of the transmitted data. Security, in this sense, has a number of different components. First, transmitted data should be secure from tampering and therefore the service should be secure from unauthorized entry into at both the physical and the functional levels. Second, the system should be secure from a time and control standpoint. In other words, a user should be authenticated before entry is authorized and entry should be provided at the appropriate level and in a timely manner. Finally, unauthorized third parties should be prevented from reading transmitted data.
Current cable television networks do not meet these requirements due to the nature of the service itself. Current systems send all data signals through the tunk cable directly to the subscriber's modem, which in turn filters the signal to a preset frequency and passes the corresponding data to the computer. Given this arrangement, a hacker can intercept third party data or service requests. In addition, a hacker could “piggyback” along with an authenticated user and, once inside the password protected data network, access and/or tamper with sensitive data.
Another drawback of current cable television networks is the lack of electrical isolation between the subscriber and the trunk cable used to transmit the data. This lack of electrical isolation allows electrical noise, such as is created by household appliances such as hair dryers, vacuum cleaners, or the like, to corrupt the signals being passed through the trunk cable and degrade system performance.
Therefore, there is a need for an apparatus for efficiently accessing, managing, and protecting information communicated over cable television networks that isolates each subscriber such that unauthorized access to, and/or tampering with, third parties' data is prevented and such that unwanted electrical noise is not imparted to the network.
SUMMARY OF THE INVENTION
The present invention is an access device for use with a cable television communications network and a network utilizing such a device. In its most basic form, the network includes a cable head end in communication with a television source and a data source. A trunk feed cable is in communication with the cable head end and is utilized for carrying a cable television network signal that includes a television signal and a data signal to at least one subscriber. At least one access device is placed in communication with the trunk feed cable. The access device includes an upstream frequency translator for translating a subscriber service request signal to a first predetermined frequency, a communications modem for sending the translated subscriber request signal to the data source, receiving the cable television network signal from the data source, and sending a subscriber termination signal to indicate a termination of service. A television band pass filter is included in the access device for filtering the composite television signal band from the cable television network in a non-modified form and a non-television band pass filter for filtering a data signal from the cable television network signal. A downstream frequency translator translates the filtered data signal from the cable television signal band to a second predetermined frequency. The access device also includes a microprocessor for generating the allocated frequency slots assigned to the subscriber by the head end, setting the upstream frequency translator to translate the subscriber service request signal to the first predetermined frequency, and setting the downstream frequency translator to translate the data signal to the second predetermined frequency. The network further includes at least one drop cable in communication with the access device for transmitting the television signal and the translated data signal from the access device to the subscriber and for sending the service request signal from the subscriber to the access device. Finally, the network also includes a subscriber cable modem in communication with the drop cable for receiving and converting the translated data signal from the access device into a computer readable form and for converting a service request signal from the computer and sending the converted signal to the access device.
In operation, the subscriber sends a service request from the computer, the subscriber cable modem converts the service request signal from the computer and sends the converted signal through the drop cable to the access device. The access device then requests both upstream and downstream frequency slots from the head end. This authorizatoin and allocation is accomplished via a low speed data modem utilizing the service channel on the trunk cable. The data source responds to the service request signal and send a cable television network signal through the head end and the trunk cable back to the access device. The access device then filters a television signal and a data signal, translates the data signal to a second predetermined frequency, and sends the translated data signal to the subscriber cable modem through the drop cable. The subscriber cable modem then converts the translated data signal into a computer readable form and sends the converted-data signal to the computer.
Therefore, it is an aspect of the invention to provide an apparatus for managing data over a CATV system that is outside the physical control/access of the user, but is installed in the close proximity to the user.
It is a further aspect of the invention to provide an apparatus for managing data over a CATV system that may be mounted on a pole, strand, in a distribution box for trenched systems, or in a secured equipment or distribution box for multiple users.
It is a further aspect of the invention to provide an apparatus for managing data over a CATV system that is operationally transparent to the user and to other users on the network.
It is a further aspect of the invention to provide an apparatus for managing data over a CATV system that prevents unauthorized access to information on the network.
It is a further aspect of the invention to provide an apparatus for
Faile Andrew
Koenig Andrew Y.
Ritchie William B.
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