Abstract: A method and apparatus for storing both protected and clear data on a single storage device 34. The apparatus includes storage media 34 for storing digital material such as video, sound, pictures and text. The media is partitioned into protected 94 and unprotected areas 98. The apparatus further includes circuitry 10 for accessing, decrypting and encrypting data. This circuitry includes a controller 16 with associated ROM 18 for directing the controller 16 and communication ports 20 for connecting to a source of content 12 and a sink 14 for storage. The method includes partitioning a storage device into clear 98 and protected areas 94 and directing protected data to the protected area 94 and clear data to the clear area 98. One embodiment includes an encrypted directory in the protected area 94 and a conventional directory in the clear area 98.

Abstract: An AV packet switch comprises a multiplexer system having multiple multiplexer input terminals and multiple multiplexer output terminals, a particular multiplexer input terminal capable to receive an input stream synchronized with a first clock signal, a particular multiplexer output terminal capable to receive the input stream from the particular multiplexer input terminal; and an output stream destination synchronizer coupled to the particular switch output terminal capable to synchronize the input stream with a destination's clock signal.

Abstract: A data communication system for providing data transmission between a plurality of individually addressable local computer networks, by utilizing single node switching across a common passive bus medium. The passive bus medium is characterized as having a plurality of separate conductors of limited length that are each commonly connected to individual bus interface circuits for each local computer network. Each bus interface circuit has a number of dedicated address data ports, message data ports and control ports that are connected to separate dedicated conductors of the passive bus medium for transmitting data to and receiving data from other local computer networks. Each message transmission of data on the passive bus medium is divided into a number of mini-packets each of which contain a number of parallely transmitted bits corresponding to the number of dedicated address and message conductors in the passive bus medium.

Abstract: A coaxial cable coupler that provides a low impedance through conductor for a passive coaxial transmission cable and a high impedance tap to periodic transmission means and receiver means. The tap connection is a removable connection that is formed by a resilient electrical conductor compressed between exposed portions of the main transmission through conductor and an exposed tap conductor interconnecting the high impedance networks of the transmission means and the receiver means.

Abstract: A plurality of transceivers frequently share a common communication medium or radio frequency channel. A broadcast channel can support only a limited number of transceivers. At some point, the shared channel will become so busy that additional transceivers will divide up more of an already inadequate bandwidth. To reduce the traffic, a broadcast channel is split into separate segments. A segment interface apparatus is used to couple two broadcast segments together. A hierarchical address is employed in the header of each packet transmitted on the medium. The segment interface apparatus compares fields in the header with that of internal registers to determine if the packet should be repeated on the other broadcast segment. An access level within the packet is decremented by the segment interface to control the number of times a packet is repeated.

Abstract: When a plurality of transmitters share a common communication medium or radio frequency channel, collision interference will result when two or more transmissions overlap in time. An interference detector apparatus is used to sense this simultaneous transmission. The use of code redundancy in transmitting data over the medium in conjunction with a code classifying decoder apparatus permits interference to be detected within the receiver. The interference detector signal interrupts its own transmitter or a plurality of transmitters, when collision interference is present on the medium. This truncation of transmission improves the channel capacity of the shared medium. The interference signal can also be used to inhibit a receiver from generating erroneous data during the interference duration.

Abstract: The Local Network Architecture (LNA) is an organization of a data communication network where the control and access to the communication channel is handled local to each user device interface. The device interface (Local Netowrk Architecture Interface or LNAI) is an electronic module which interfaces a user with the LNA communication network. This device adapter contains both a network port and a user interface port. This interface accepts user data and fragments it into data packets for shipment over a shared communication medium which is connected to the network port. A communication microprocessor is used to implement the functions of data buffering, routing, sequencing, flow control, acknowledging and error checking of data. Such distributed control eliminates the need for messages in the network to be forwarded to a message flow control process or computer station.

Abstract: When a plurality of transceivers share a common communication medium or radio frequency channel, then collision interference will result when two or more transceivers transmit simultaneously. In order to detect this simultaneous transmission, an interference detector apparatus compares the received information after demodulation to that of the transmitted information before modulation. The classification of the distorted signals into either of the two decoded output states permits this interference to be detected with a comparison. The output from the interference detector is used to interrupt the transmitter when collision interference is present on the medium. It is also used to inhibit the receiver from generating erroneous data during the interference duration.

Abstract: An encoder of a transmitter converts digital data or analog signal information into an encoded sequence or waveform required by a communication channel. If a plurality of transmitters are to share a common channel or medium, then the correlation properties of the encoded signal are important. The encoding apparatus should employ a code which is not very susceptible to noise, yet will permit the detection of multiple transmissions of similar spectrum signals. The apparatus disclosed in this specification is concerned with a binary digital information encoder whose input is either a "zero" or "one" state. The encoder generates a ternary code sequence for encoding one binary input state with the sequence + 1,+1,0,0,-1,-1 and the other binary input state with the sequence represented by +1,0,+1,-1,0,-1.

Abstract: With respect to a synchronous communications receiver, this specification discloses a decoder for generating a clock signal to synchronize the receiver with the information data rate of the received signal. The implementation of a decoder apparatus as a periodic finite state machine allows a clock signal to be extracted from the energy or transitions of the encoded signal. Such a decoder can define clock information over a large range of data rates. A bandpass filter tuned to the characteristic frequency being received can be coupled to the input of the decoder to limit the synchronization range to that desired by the receiver.

Abstract: An apparatus for enabling communications between two or more transceivers when a plurality of transceivers share a common communication medium or channel. The geographical locations of the transceivers are such that the propagation delay between any source to destination pair is relatively a small function of the transmission duration or packet time. In order to prevent two or more transceivers from simultaneously transmitting over the common medium, each transceiver requires a control apparatus. The simultaneous transmission by two or more transceivers is not very likely due to different start times. However, if such start times differ by less than the propagation delay between the transceivers then interference will result. Hence the control apparatus includes a means of resolving such contention interferences by providing a retransmission delay to govern the transmission.